10 files changed, 534 insertions, 167 deletions

diff --git a/crates/ra_ide/Cargo.toml b/crates/ra_ide/Cargo.toml
index 6f8107491..f4181c4eb 100644
--- a/crates/ra_ide/Cargo.toml
+++ b/crates/ra_ide/Cargo.toml
@@ -17,7 +17,7 @@ indexmap = "1.3.2"
 itertools = "0.9.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
-rand = { version = "0.7.3", features = ["small_rng"] }
+oorandom = "11.1.2"
 
 stdx = { path = "../stdx" }
 
diff --git a/crates/ra_ide/src/completion/complete_attribute.rs b/crates/ra_ide/src/completion/complete_attribute.rs
index d268c92be..109c5e9a8 100644
--- a/crates/ra_ide/src/completion/complete_attribute.rs
+++ b/crates/ra_ide/src/completion/complete_attribute.rs
@@ -13,13 +13,19 @@ use crate::completion::{
 
 pub(super) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
     let attribute = ctx.attribute_under_caret.as_ref()?;
-
     match (attribute.path(), attribute.input()) {
         (Some(path), Some(ast::AttrInput::TokenTree(token_tree)))
             if path.to_string() == "derive" =>
         {
             complete_derive(acc, ctx, token_tree)
         }
+        (Some(path), Some(ast::AttrInput::TokenTree(token_tree)))
+            if ["allow", "warn", "deny", "forbid"]
+                .iter()
+                .any(|lint_level| lint_level == &path.to_string()) =>
+        {
+            complete_lint(acc, ctx, token_tree)
+        }
         (_, Some(ast::AttrInput::TokenTree(_token_tree))) => {}
         _ => complete_attribute_start(acc, ctx, attribute),
     }
@@ -125,7 +131,7 @@ const ATTRIBUTES: &[AttrCompletion] = &[
 ];
 
 fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, derive_input: ast::TokenTree) {
-    if let Ok(existing_derives) = parse_derive_input(derive_input) {
+    if let Ok(existing_derives) = parse_comma_sep_input(derive_input) {
         for derive_completion in DEFAULT_DERIVE_COMPLETIONS
             .into_iter()
             .filter(|completion| !existing_derives.contains(completion.label))
@@ -158,7 +164,26 @@ fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, derive_input:
     }
 }
 
-fn parse_derive_input(derive_input: ast::TokenTree) -> Result<FxHashSet<String>, ()> {
+fn complete_lint(acc: &mut Completions, ctx: &CompletionContext, derive_input: ast::TokenTree) {
+    if let Ok(existing_lints) = parse_comma_sep_input(derive_input) {
+        for lint_completion in DEFAULT_LINT_COMPLETIONS
+            .into_iter()
+            .filter(|completion| !existing_lints.contains(completion.label))
+        {
+            acc.add(
+                CompletionItem::new(
+                    CompletionKind::Attribute,
+                    ctx.source_range(),
+                    lint_completion.label,
+                )
+                .kind(CompletionItemKind::Attribute)
+                .detail(lint_completion.description),
+            );
+        }
+    }
+}
+
+fn parse_comma_sep_input(derive_input: ast::TokenTree) -> Result<FxHashSet<String>, ()> {
     match (derive_input.left_delimiter_token(), derive_input.right_delimiter_token()) {
         (Some(left_paren), Some(right_paren))
             if left_paren.kind() == SyntaxKind::L_PAREN
@@ -212,6 +237,7 @@ struct DeriveCompletion {
 
 /// Standard Rust derives and the information about their dependencies
 /// (the dependencies are needed so that the main derive don't break the compilation when added)
+#[rustfmt::skip]
 const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
     DeriveCompletion { label: "Clone", dependencies: &[] },
     DeriveCompletion { label: "Copy", dependencies: &["Clone"] },
@@ -224,6 +250,130 @@ const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
     DeriveCompletion { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
 ];
 
+struct LintCompletion {
+    label: &'static str,
+    description: &'static str,
+}
+
+#[rustfmt::skip]
+const DEFAULT_LINT_COMPLETIONS: &[LintCompletion] = &[
+    LintCompletion { label: "absolute_paths_not_starting_with_crate", description: r#"fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name"# },
+    LintCompletion { label: "anonymous_parameters", description: r#"detects anonymous parameters"# },
+    LintCompletion { label: "box_pointers", description: r#"use of owned (Box type) heap memory"# },
+    LintCompletion { label: "deprecated_in_future", description: r#"detects use of items that will be deprecated in a future version"# },
+    LintCompletion { label: "elided_lifetimes_in_paths", description: r#"hidden lifetime parameters in types are deprecated"# },
+    LintCompletion { label: "explicit_outlives_requirements", description: r#"outlives requirements can be inferred"# },
+    LintCompletion { label: "indirect_structural_match", description: r#"pattern with const indirectly referencing non-structural-match type"# },
+    LintCompletion { label: "keyword_idents", description: r#"detects edition keywords being used as an identifier"# },
+    LintCompletion { label: "macro_use_extern_crate", description: r#"the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system"# },
+    LintCompletion { label: "meta_variable_misuse", description: r#"possible meta-variable misuse at macro definition"# },
+    LintCompletion { label: "missing_copy_implementations", description: r#"detects potentially-forgotten implementations of `Copy`"# },
+    LintCompletion { label: "missing_crate_level_docs", description: r#"detects crates with no crate-level documentation"# },
+    LintCompletion { label: "missing_debug_implementations", description: r#"detects missing implementations of Debug"# },
+    LintCompletion { label: "missing_docs", description: r#"detects missing documentation for public members"# },
+    LintCompletion { label: "missing_doc_code_examples", description: r#"detects publicly-exported items without code samples in their documentation"# },
+    LintCompletion { label: "non_ascii_idents", description: r#"detects non-ASCII identifiers"# },
+    LintCompletion { label: "private_doc_tests", description: r#"detects code samples in docs of private items not documented by rustdoc"# },
+    LintCompletion { label: "single_use_lifetimes", description: r#"detects lifetime parameters that are only used once"# },
+    LintCompletion { label: "trivial_casts", description: r#"detects trivial casts which could be removed"# },
+    LintCompletion { label: "trivial_numeric_casts", description: r#"detects trivial casts of numeric types which could be removed"# },
+    LintCompletion { label: "unaligned_references", description: r#"detects unaligned references to fields of packed structs"# },
+    LintCompletion { label: "unreachable_pub", description: r#"`pub` items not reachable from crate root"# },
+    LintCompletion { label: "unsafe_code", description: r#"usage of `unsafe` code"# },
+    LintCompletion { label: "unsafe_op_in_unsafe_fn", description: r#"unsafe operations in unsafe functions without an explicit unsafe block are deprecated"# },
+    LintCompletion { label: "unstable_features", description: r#"enabling unstable features (deprecated. do not use)"# },
+    LintCompletion { label: "unused_crate_dependencies", description: r#"crate dependencies that are never used"# },
+    LintCompletion { label: "unused_extern_crates", description: r#"extern crates that are never used"# },
+    LintCompletion { label: "unused_import_braces", description: r#"unnecessary braces around an imported item"# },
+    LintCompletion { label: "unused_lifetimes", description: r#"detects lifetime parameters that are never used"# },
+    LintCompletion { label: "unused_qualifications", description: r#"detects unnecessarily qualified names"# },
+    LintCompletion { label: "unused_results", description: r#"unused result of an expression in a statement"# },
+    LintCompletion { label: "variant_size_differences", description: r#"detects enums with widely varying variant sizes"# },
+    LintCompletion { label: "array_into_iter", description: r#"detects calling `into_iter` on arrays"# },
+    LintCompletion { label: "asm_sub_register", description: r#"using only a subset of a register for inline asm inputs"# },
+    LintCompletion { label: "bare_trait_objects", description: r#"suggest using `dyn Trait` for trait objects"# },
+    LintCompletion { label: "bindings_with_variant_name", description: r#"detects pattern bindings with the same name as one of the matched variants"# },
+    LintCompletion { label: "cenum_impl_drop_cast", description: r#"a C-like enum implementing Drop is cast"# },
+    LintCompletion { label: "clashing_extern_declarations", description: r#"detects when an extern fn has been declared with the same name but different types"# },
+    LintCompletion { label: "coherence_leak_check", description: r#"distinct impls distinguished only by the leak-check code"# },
+    LintCompletion { label: "confusable_idents", description: r#"detects visually confusable pairs between identifiers"# },
+    LintCompletion { label: "dead_code", description: r#"detect unused, unexported items"# },
+    LintCompletion { label: "deprecated", description: r#"detects use of deprecated items"# },
+    LintCompletion { label: "ellipsis_inclusive_range_patterns", description: r#"`...` range patterns are deprecated"# },
+    LintCompletion { label: "exported_private_dependencies", description: r#"public interface leaks type from a private dependency"# },
+    LintCompletion { label: "illegal_floating_point_literal_pattern", description: r#"floating-point literals cannot be used in patterns"# },
+    LintCompletion { label: "improper_ctypes", description: r#"proper use of libc types in foreign modules"# },
+    LintCompletion { label: "improper_ctypes_definitions", description: r#"proper use of libc types in foreign item definitions"# },
+    LintCompletion { label: "incomplete_features", description: r#"incomplete features that may function improperly in some or all cases"# },
+    LintCompletion { label: "inline_no_sanitize", description: r#"detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`"# },
+    LintCompletion { label: "intra_doc_link_resolution_failure", description: r#"failures in resolving intra-doc link targets"# },
+    LintCompletion { label: "invalid_codeblock_attributes", description: r#"codeblock attribute looks a lot like a known one"# },
+    LintCompletion { label: "invalid_value", description: r#"an invalid value is being created (such as a NULL reference)"# },
+    LintCompletion { label: "irrefutable_let_patterns", description: r#"detects irrefutable patterns in if-let and while-let statements"# },
+    LintCompletion { label: "late_bound_lifetime_arguments", description: r#"detects generic lifetime arguments in path segments with late bound lifetime parameters"# },
+    LintCompletion { label: "mixed_script_confusables", description: r#"detects Unicode scripts whose mixed script confusables codepoints are solely used"# },
+    LintCompletion { label: "mutable_borrow_reservation_conflict", description: r#"reservation of a two-phased borrow conflicts with other shared borrows"# },
+    LintCompletion { label: "non_camel_case_types", description: r#"types, variants, traits and type parameters should have camel case names"# },
+    LintCompletion { label: "non_shorthand_field_patterns", description: r#"using `Struct { x: x }` instead of `Struct { x }` in a pattern"# },
+    LintCompletion { label: "non_snake_case", description: r#"variables, methods, functions, lifetime parameters and modules should have snake case names"# },
+    LintCompletion { label: "non_upper_case_globals", description: r#"static constants should have uppercase identifiers"# },
+    LintCompletion { label: "no_mangle_generic_items", description: r#"generic items must be mangled"# },
+    LintCompletion { label: "overlapping_patterns", description: r#"detects overlapping patterns"# },
+    LintCompletion { label: "path_statements", description: r#"path statements with no effect"# },
+    LintCompletion { label: "private_in_public", description: r#"detect private items in public interfaces not caught by the old implementation"# },
+    LintCompletion { label: "proc_macro_derive_resolution_fallback", description: r#"detects proc macro derives using inaccessible names from parent modules"# },
+    LintCompletion { label: "redundant_semicolons", description: r#"detects unnecessary trailing semicolons"# },
+    LintCompletion { label: "renamed_and_removed_lints", description: r#"lints that have been renamed or removed"# },
+    LintCompletion { label: "safe_packed_borrows", description: r#"safe borrows of fields of packed structs were erroneously allowed"# },
+    LintCompletion { label: "stable_features", description: r#"stable features found in `#[feature]` directive"# },
+    LintCompletion { label: "trivial_bounds", description: r#"these bounds don't depend on an type parameters"# },
+    LintCompletion { label: "type_alias_bounds", description: r#"bounds in type aliases are not enforced"# },
+    LintCompletion { label: "tyvar_behind_raw_pointer", description: r#"raw pointer to an inference variable"# },
+    LintCompletion { label: "uncommon_codepoints", description: r#"detects uncommon Unicode codepoints in identifiers"# },
+    LintCompletion { label: "unconditional_recursion", description: r#"functions that cannot return without calling themselves"# },
+    LintCompletion { label: "unknown_lints", description: r#"unrecognized lint attribute"# },
+    LintCompletion { label: "unnameable_test_items", description: r#"detects an item that cannot be named being marked as `#[test_case]`"# },
+    LintCompletion { label: "unreachable_code", description: r#"detects unreachable code paths"# },
+    LintCompletion { label: "unreachable_patterns", description: r#"detects unreachable patterns"# },
+    LintCompletion { label: "unstable_name_collisions", description: r#"detects name collision with an existing but unstable method"# },
+    LintCompletion { label: "unused_allocation", description: r#"detects unnecessary allocations that can be eliminated"# },
+    LintCompletion { label: "unused_assignments", description: r#"detect assignments that will never be read"# },
+    LintCompletion { label: "unused_attributes", description: r#"detects attributes that were not used by the compiler"# },
+    LintCompletion { label: "unused_braces", description: r#"unnecessary braces around an expression"# },
+    LintCompletion { label: "unused_comparisons", description: r#"comparisons made useless by limits of the types involved"# },
+    LintCompletion { label: "unused_doc_comments", description: r#"detects doc comments that aren't used by rustdoc"# },
+    LintCompletion { label: "unused_features", description: r#"unused features found in crate-level `#[feature]` directives"# },
+    LintCompletion { label: "unused_imports", description: r#"imports that are never used"# },
+    LintCompletion { label: "unused_labels", description: r#"detects labels that are never used"# },
+    LintCompletion { label: "unused_macros", description: r#"detects macros that were not used"# },
+    LintCompletion { label: "unused_must_use", description: r#"unused result of a type flagged as `#[must_use]`"# },
+    LintCompletion { label: "unused_mut", description: r#"detect mut variables which don't need to be mutable"# },
+    LintCompletion { label: "unused_parens", description: r#"`if`, `match`, `while` and `return` do not need parentheses"# },
+    LintCompletion { label: "unused_unsafe", description: r#"unnecessary use of an `unsafe` block"# },
+    LintCompletion { label: "unused_variables", description: r#"detect variables which are not used in any way"# },
+    LintCompletion { label: "warnings", description: r#"mass-change the level for lints which produce warnings"# },
+    LintCompletion { label: "where_clauses_object_safety", description: r#"checks the object safety of where clauses"# },
+    LintCompletion { label: "while_true", description: r#"suggest using `loop { }` instead of `while true { }`"# },
+    LintCompletion { label: "ambiguous_associated_items", description: r#"ambiguous associated items"# },
+    LintCompletion { label: "arithmetic_overflow", description: r#"arithmetic operation overflows"# },
+    LintCompletion { label: "conflicting_repr_hints", description: r#"conflicts between `#[repr(..)]` hints that were previously accepted and used in practice"# },
+    LintCompletion { label: "const_err", description: r#"constant evaluation detected erroneous expression"# },
+    LintCompletion { label: "ill_formed_attribute_input", description: r#"ill-formed attribute inputs that were previously accepted and used in practice"# },
+    LintCompletion { label: "incomplete_include", description: r#"trailing content in included file"# },
+    LintCompletion { label: "invalid_type_param_default", description: r#"type parameter default erroneously allowed in invalid location"# },
+    LintCompletion { label: "macro_expanded_macro_exports_accessed_by_absolute_paths", description: r#"macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths"# },
+    LintCompletion { label: "missing_fragment_specifier", description: r#"detects missing fragment specifiers in unused `macro_rules!` patterns"# },
+    LintCompletion { label: "mutable_transmutes", description: r#"mutating transmuted &mut T from &T may cause undefined behavior"# },
+    LintCompletion { label: "no_mangle_const_items", description: r#"const items will not have their symbols exported"# },
+    LintCompletion { label: "order_dependent_trait_objects", description: r#"trait-object types were treated as different depending on marker-trait order"# },
+    LintCompletion { label: "overflowing_literals", description: r#"literal out of range for its type"# },
+    LintCompletion { label: "patterns_in_fns_without_body", description: r#"patterns in functions without body were erroneously allowed"# },
+    LintCompletion { label: "pub_use_of_private_extern_crate", description: r#"detect public re-exports of private extern crates"# },
+    LintCompletion { label: "soft_unstable", description: r#"a feature gate that doesn't break dependent crates"# },
+    LintCompletion { label: "unconditional_panic", description: r#"operation will cause a panic at runtime"# },
+    LintCompletion { label: "unknown_crate_types", description: r#"unknown crate type found in `#[crate_type]` directive"# },
+];
+
 #[cfg(test)]
 mod tests {
     use expect::{expect, Expect};
@@ -257,6 +407,130 @@ struct Test {}
     }
 
     #[test]
+    fn empty_lint_completion() {
+        check(
+            r#"#[allow(<|>)]"#,
+            expect![[r#"
+                at absolute_paths_not_starting_with_crate fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name
+                at ambiguous_associated_items ambiguous associated items
+                at anonymous_parameters detects anonymous parameters
+                at arithmetic_overflow arithmetic operation overflows
+                at array_into_iter  detects calling `into_iter` on arrays
+                at asm_sub_register using only a subset of a register for inline asm inputs
+                at bare_trait_objects suggest using `dyn Trait` for trait objects
+                at bindings_with_variant_name detects pattern bindings with the same name as one of the matched variants
+                at box_pointers     use of owned (Box type) heap memory
+                at cenum_impl_drop_cast a C-like enum implementing Drop is cast
+                at clashing_extern_declarations detects when an extern fn has been declared with the same name but different types
+                at coherence_leak_check distinct impls distinguished only by the leak-check code
+                at conflicting_repr_hints conflicts between `#[repr(..)]` hints that were previously accepted and used in practice
+                at confusable_idents detects visually confusable pairs between identifiers
+                at const_err        constant evaluation detected erroneous expression
+                at dead_code        detect unused, unexported items
+                at deprecated       detects use of deprecated items
+                at deprecated_in_future detects use of items that will be deprecated in a future version
+                at elided_lifetimes_in_paths hidden lifetime parameters in types are deprecated
+                at ellipsis_inclusive_range_patterns `...` range patterns are deprecated
+                at explicit_outlives_requirements outlives requirements can be inferred
+                at exported_private_dependencies public interface leaks type from a private dependency
+                at ill_formed_attribute_input ill-formed attribute inputs that were previously accepted and used in practice
+                at illegal_floating_point_literal_pattern floating-point literals cannot be used in patterns
+                at improper_ctypes  proper use of libc types in foreign modules
+                at improper_ctypes_definitions proper use of libc types in foreign item definitions
+                at incomplete_features incomplete features that may function improperly in some or all cases
+                at incomplete_include trailing content in included file
+                at indirect_structural_match pattern with const indirectly referencing non-structural-match type
+                at inline_no_sanitize detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`
+                at intra_doc_link_resolution_failure failures in resolving intra-doc link targets
+                at invalid_codeblock_attributes codeblock attribute looks a lot like a known one
+                at invalid_type_param_default type parameter default erroneously allowed in invalid location
+                at invalid_value    an invalid value is being created (such as a NULL reference)
+                at irrefutable_let_patterns detects irrefutable patterns in if-let and while-let statements
+                at keyword_idents   detects edition keywords being used as an identifier
+                at late_bound_lifetime_arguments detects generic lifetime arguments in path segments with late bound lifetime parameters
+                at macro_expanded_macro_exports_accessed_by_absolute_paths macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths
+                at macro_use_extern_crate the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system
+                at meta_variable_misuse possible meta-variable misuse at macro definition
+                at missing_copy_implementations detects potentially-forgotten implementations of `Copy`
+                at missing_crate_level_docs detects crates with no crate-level documentation
+                at missing_debug_implementations detects missing implementations of Debug
+                at missing_doc_code_examples detects publicly-exported items without code samples in their documentation
+                at missing_docs     detects missing documentation for public members
+                at missing_fragment_specifier detects missing fragment specifiers in unused `macro_rules!` patterns
+                at mixed_script_confusables detects Unicode scripts whose mixed script confusables codepoints are solely used
+                at mutable_borrow_reservation_conflict reservation of a two-phased borrow conflicts with other shared borrows
+                at mutable_transmutes mutating transmuted &mut T from &T may cause undefined behavior
+                at no_mangle_const_items const items will not have their symbols exported
+                at no_mangle_generic_items generic items must be mangled
+                at non_ascii_idents detects non-ASCII identifiers
+                at non_camel_case_types types, variants, traits and type parameters should have camel case names
+                at non_shorthand_field_patterns using `Struct { x: x }` instead of `Struct { x }` in a pattern
+                at non_snake_case   variables, methods, functions, lifetime parameters and modules should have snake case names
+                at non_upper_case_globals static constants should have uppercase identifiers
+                at order_dependent_trait_objects trait-object types were treated as different depending on marker-trait order
+                at overflowing_literals literal out of range for its type
+                at overlapping_patterns detects overlapping patterns
+                at path_statements  path statements with no effect
+                at patterns_in_fns_without_body patterns in functions without body were erroneously allowed
+                at private_doc_tests detects code samples in docs of private items not documented by rustdoc
+                at private_in_public detect private items in public interfaces not caught by the old implementation
+                at proc_macro_derive_resolution_fallback detects proc macro derives using inaccessible names from parent modules
+                at pub_use_of_private_extern_crate detect public re-exports of private extern crates
+                at redundant_semicolons detects unnecessary trailing semicolons
+                at renamed_and_removed_lints lints that have been renamed or removed
+                at safe_packed_borrows safe borrows of fields of packed structs were erroneously allowed
+                at single_use_lifetimes detects lifetime parameters that are only used once
+                at soft_unstable    a feature gate that doesn't break dependent crates
+                at stable_features  stable features found in `#[feature]` directive
+                at trivial_bounds   these bounds don't depend on an type parameters
+                at trivial_casts    detects trivial casts which could be removed
+                at trivial_numeric_casts detects trivial casts of numeric types which could be removed
+                at type_alias_bounds bounds in type aliases are not enforced
+                at tyvar_behind_raw_pointer raw pointer to an inference variable
+                at unaligned_references detects unaligned references to fields of packed structs
+                at uncommon_codepoints detects uncommon Unicode codepoints in identifiers
+                at unconditional_panic operation will cause a panic at runtime
+                at unconditional_recursion functions that cannot return without calling themselves
+                at unknown_crate_types unknown crate type found in `#[crate_type]` directive
+                at unknown_lints    unrecognized lint attribute
+                at unnameable_test_items detects an item that cannot be named being marked as `#[test_case]`
+                at unreachable_code detects unreachable code paths
+                at unreachable_patterns detects unreachable patterns
+                at unreachable_pub  `pub` items not reachable from crate root
+                at unsafe_code      usage of `unsafe` code
+                at unsafe_op_in_unsafe_fn unsafe operations in unsafe functions without an explicit unsafe block are deprecated
+                at unstable_features enabling unstable features (deprecated. do not use)
+                at unstable_name_collisions detects name collision with an existing but unstable method
+                at unused_allocation detects unnecessary allocations that can be eliminated
+                at unused_assignments detect assignments that will never be read
+                at unused_attributes detects attributes that were not used by the compiler
+                at unused_braces    unnecessary braces around an expression
+                at unused_comparisons comparisons made useless by limits of the types involved
+                at unused_crate_dependencies crate dependencies that are never used
+                at unused_doc_comments detects doc comments that aren't used by rustdoc
+                at unused_extern_crates extern crates that are never used
+                at unused_features  unused features found in crate-level `#[feature]` directives
+                at unused_import_braces unnecessary braces around an imported item
+                at unused_imports   imports that are never used
+                at unused_labels    detects labels that are never used
+                at unused_lifetimes detects lifetime parameters that are never used
+                at unused_macros    detects macros that were not used
+                at unused_must_use  unused result of a type flagged as `#[must_use]`
+                at unused_mut       detect mut variables which don't need to be mutable
+                at unused_parens    `if`, `match`, `while` and `return` do not need parentheses
+                at unused_qualifications detects unnecessarily qualified names
+                at unused_results   unused result of an expression in a statement
+                at unused_unsafe    unnecessary use of an `unsafe` block
+                at unused_variables detect variables which are not used in any way
+                at variant_size_differences detects enums with widely varying variant sizes
+                at warnings         mass-change the level for lints which produce warnings
+                at where_clauses_object_safety checks the object safety of where clauses
+                at while_true       suggest using `loop { }` instead of `while true { }`
+        "#]],
+        )
+    }
+
+    #[test]
     fn no_completion_for_incorrect_derive() {
         check(
             r#"
@@ -325,7 +599,7 @@ struct Test {}
 
     #[test]
     fn test_attribute_completion_inside_nested_attr() {
-        check(r#"#[allow(<|>)]"#, expect![[]])
+        check(r#"#[cfg(<|>)]"#, expect![[]])
     }
 
     #[test]
diff --git a/crates/ra_ide/src/diagnostics.rs b/crates/ra_ide/src/diagnostics.rs
index e029af0dc..897177d05 100644
--- a/crates/ra_ide/src/diagnostics.rs
+++ b/crates/ra_ide/src/diagnostics.rs
@@ -7,7 +7,7 @@
 use std::cell::RefCell;
 
 use hir::{
-    diagnostics::{AstDiagnostic, Diagnostic as _, DiagnosticSink},
+    diagnostics::{AstDiagnostic, Diagnostic as _, DiagnosticSinkBuilder},
     HasSource, HirDisplay, Semantics, VariantDef,
 };
 use itertools::Itertools;
@@ -29,7 +29,11 @@ pub enum Severity {
     WeakWarning,
 }
 
-pub(crate) fn diagnostics(db: &RootDatabase, file_id: FileId) -> Vec<Diagnostic> {
+pub(crate) fn diagnostics(
+    db: &RootDatabase,
+    file_id: FileId,
+    enable_experimental: bool,
+) -> Vec<Diagnostic> {
     let _p = profile("diagnostics");
     let sema = Semantics::new(db);
     let parse = db.parse(file_id);
@@ -48,79 +52,85 @@ pub(crate) fn diagnostics(db: &RootDatabase, file_id: FileId) -> Vec<Diagnostic>
         check_struct_shorthand_initialization(&mut res, file_id, &node);
     }
     let res = RefCell::new(res);
-    let mut sink = DiagnosticSink::new(|d| {
-        res.borrow_mut().push(Diagnostic {
-            message: d.message(),
-            range: sema.diagnostics_range(d).range,
-            severity: Severity::Error,
-            fix: None,
-        })
-    })
-    .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
-        let original_file = d.source().file_id.original_file(db);
-        let fix = Fix::new(
-            "Create module",
-            FileSystemEdit::CreateFile { anchor: original_file, dst: d.candidate.clone() }.into(),
-        );
-        res.borrow_mut().push(Diagnostic {
-            range: sema.diagnostics_range(d).range,
-            message: d.message(),
-            severity: Severity::Error,
-            fix: Some(fix),
+    let mut sink = DiagnosticSinkBuilder::new()
+        .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
+            let original_file = d.source().file_id.original_file(db);
+            let fix = Fix::new(
+                "Create module",
+                FileSystemEdit::CreateFile { anchor: original_file, dst: d.candidate.clone() }
+                    .into(),
+            );
+            res.borrow_mut().push(Diagnostic {
+                range: sema.diagnostics_range(d).range,
+                message: d.message(),
+                severity: Severity::Error,
+                fix: Some(fix),
+            })
         })
-    })
-    .on::<hir::diagnostics::MissingFields, _>(|d| {
-        // Note that although we could add a diagnostics to
-        // fill the missing tuple field, e.g :
-        // `struct A(usize);`
-        // `let a = A { 0: () }`
-        // but it is uncommon usage and it should not be encouraged.
-        let fix = if d.missed_fields.iter().any(|it| it.as_tuple_index().is_some()) {
-            None
-        } else {
-            let mut field_list = d.ast(db);
-            for f in d.missed_fields.iter() {
-                let field =
-                    make::record_field(make::name_ref(&f.to_string()), Some(make::expr_unit()));
-                field_list = field_list.append_field(&field);
-            }
-
-            let edit = {
-                let mut builder = TextEditBuilder::default();
-                algo::diff(&d.ast(db).syntax(), &field_list.syntax()).into_text_edit(&mut builder);
-                builder.finish()
+        .on::<hir::diagnostics::MissingFields, _>(|d| {
+            // Note that although we could add a diagnostics to
+            // fill the missing tuple field, e.g :
+            // `struct A(usize);`
+            // `let a = A { 0: () }`
+            // but it is uncommon usage and it should not be encouraged.
+            let fix = if d.missed_fields.iter().any(|it| it.as_tuple_index().is_some()) {
+                None
+            } else {
+                let mut field_list = d.ast(db);
+                for f in d.missed_fields.iter() {
+                    let field =
+                        make::record_field(make::name_ref(&f.to_string()), Some(make::expr_unit()));
+                    field_list = field_list.append_field(&field);
+                }
+
+                let edit = {
+                    let mut builder = TextEditBuilder::default();
+                    algo::diff(&d.ast(db).syntax(), &field_list.syntax())
+                        .into_text_edit(&mut builder);
+                    builder.finish()
+                };
+                Some(Fix::new("Fill struct fields", SourceFileEdit { file_id, edit }.into()))
             };
-            Some(Fix::new("Fill struct fields", SourceFileEdit { file_id, edit }.into()))
-        };
 
-        res.borrow_mut().push(Diagnostic {
-            range: sema.diagnostics_range(d).range,
-            message: d.message(),
-            severity: Severity::Error,
-            fix,
+            res.borrow_mut().push(Diagnostic {
+                range: sema.diagnostics_range(d).range,
+                message: d.message(),
+                severity: Severity::Error,
+                fix,
+            })
         })
-    })
-    .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
-        let node = d.ast(db);
-        let replacement = format!("Ok({})", node.syntax());
-        let edit = TextEdit::replace(node.syntax().text_range(), replacement);
-        let source_change = SourceFileEdit { file_id, edit }.into();
-        let fix = Fix::new("Wrap with ok", source_change);
-        res.borrow_mut().push(Diagnostic {
-            range: sema.diagnostics_range(d).range,
-            message: d.message(),
-            severity: Severity::Error,
-            fix: Some(fix),
+        .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
+            let node = d.ast(db);
+            let replacement = format!("Ok({})", node.syntax());
+            let edit = TextEdit::replace(node.syntax().text_range(), replacement);
+            let source_change = SourceFileEdit { file_id, edit }.into();
+            let fix = Fix::new("Wrap with ok", source_change);
+            res.borrow_mut().push(Diagnostic {
+                range: sema.diagnostics_range(d).range,
+                message: d.message(),
+                severity: Severity::Error,
+                fix: Some(fix),
+            })
         })
-    })
-    .on::<hir::diagnostics::NoSuchField, _>(|d| {
-        res.borrow_mut().push(Diagnostic {
-            range: sema.diagnostics_range(d).range,
-            message: d.message(),
-            severity: Severity::Error,
-            fix: missing_struct_field_fix(&sema, file_id, d),
+        .on::<hir::diagnostics::NoSuchField, _>(|d| {
+            res.borrow_mut().push(Diagnostic {
+                range: sema.diagnostics_range(d).range,
+                message: d.message(),
+                severity: Severity::Error,
+                fix: missing_struct_field_fix(&sema, file_id, d),
+            })
         })
-    });
+        // Only collect experimental diagnostics when they're enabled.
+        .filter(|diag| !diag.is_experimental() || enable_experimental)
+        // Diagnostics not handled above get no fix and default treatment.
+        .build(|d| {
+            res.borrow_mut().push(Diagnostic {
+                message: d.message(),
+                range: sema.diagnostics_range(d).range,
+                severity: Severity::Error,
+                fix: None,
+            })
+        });
 
     if let Some(m) = sema.to_module_def(file_id) {
         m.diagnostics(db, &mut sink);
@@ -298,7 +308,7 @@ mod tests {
         let after = trim_indent(ra_fixture_after);
 
         let (analysis, file_position) = analysis_and_position(ra_fixture_before);
-        let diagnostic = analysis.diagnostics(file_position.file_id).unwrap().pop().unwrap();
+        let diagnostic = analysis.diagnostics(file_position.file_id, true).unwrap().pop().unwrap();
         let mut fix = diagnostic.fix.unwrap();
         let edit = fix.source_change.source_file_edits.pop().unwrap().edit;
         let target_file_contents = analysis.file_text(file_position.file_id).unwrap();
@@ -324,7 +334,7 @@ mod tests {
         let ra_fixture_after = &trim_indent(ra_fixture_after);
         let (analysis, file_pos) = analysis_and_position(ra_fixture_before);
         let current_file_id = file_pos.file_id;
-        let diagnostic = analysis.diagnostics(current_file_id).unwrap().pop().unwrap();
+        let diagnostic = analysis.diagnostics(current_file_id, true).unwrap().pop().unwrap();
         let mut fix = diagnostic.fix.unwrap();
         let edit = fix.source_change.source_file_edits.pop().unwrap();
         let changed_file_id = edit.file_id;
@@ -345,14 +355,14 @@ mod tests {
         let analysis = mock.analysis();
         let diagnostics = files
             .into_iter()
-            .flat_map(|file_id| analysis.diagnostics(file_id).unwrap())
+            .flat_map(|file_id| analysis.diagnostics(file_id, true).unwrap())
             .collect::<Vec<_>>();
         assert_eq!(diagnostics.len(), 0, "unexpected diagnostics:\n{:#?}", diagnostics);
     }
 
     fn check_expect(ra_fixture: &str, expect: Expect) {
         let (analysis, file_id) = single_file(ra_fixture);
-        let diagnostics = analysis.diagnostics(file_id).unwrap();
+        let diagnostics = analysis.diagnostics(file_id, true).unwrap();
         expect.assert_debug_eq(&diagnostics)
     }
 
diff --git a/crates/ra_ide/src/folding_ranges.rs b/crates/ra_ide/src/folding_ranges.rs
index e7ec9953f..315808890 100644
--- a/crates/ra_ide/src/folding_ranges.rs
+++ b/crates/ra_ide/src/folding_ranges.rs
@@ -84,7 +84,7 @@ fn fold_kind(kind: SyntaxKind) -> Option<FoldKind> {
     match kind {
         COMMENT => Some(FoldKind::Comment),
         USE_ITEM => Some(FoldKind::Imports),
-        ARG_LIST => Some(FoldKind::ArgList),
+        ARG_LIST | PARAM_LIST => Some(FoldKind::ArgList),
         RECORD_FIELD_DEF_LIST
         | RECORD_FIELD_PAT_LIST
         | RECORD_FIELD_LIST
@@ -386,4 +386,16 @@ const _: S = S <fold block>{
 "#,
         )
     }
+
+    #[test]
+    fn fold_multiline_params() {
+        check(
+            r#"
+fn foo<fold arglist>(
+    x: i32,
+    y: String,
+)</fold> {}
+"#,
+        )
+    }
 }
diff --git a/crates/ra_ide/src/goto_implementation.rs b/crates/ra_ide/src/goto_implementation.rs
index 3ee048f28..16a61d071 100644
--- a/crates/ra_ide/src/goto_implementation.rs
+++ b/crates/ra_ide/src/goto_implementation.rs
@@ -23,7 +23,7 @@ pub(crate) fn goto_implementation(
 
     let krate = sema.to_module_def(position.file_id)?.krate();
 
-    if let Some(nominal_def) = find_node_at_offset::<ast::NominalDef>(&syntax, position.offset) {
+    if let Some(nominal_def) = find_node_at_offset::<ast::AdtDef>(&syntax, position.offset) {
         return Some(RangeInfo::new(
             nominal_def.syntax().text_range(),
             impls_for_def(&sema, &nominal_def, krate)?,
@@ -40,13 +40,13 @@ pub(crate) fn goto_implementation(
 
 fn impls_for_def(
     sema: &Semantics<RootDatabase>,
-    node: &ast::NominalDef,
+    node: &ast::AdtDef,
     krate: Crate,
 ) -> Option<Vec<NavigationTarget>> {
     let ty = match node {
-        ast::NominalDef::StructDef(def) => sema.to_def(def)?.ty(sema.db),
-        ast::NominalDef::EnumDef(def) => sema.to_def(def)?.ty(sema.db),
-        ast::NominalDef::UnionDef(def) => sema.to_def(def)?.ty(sema.db),
+        ast::AdtDef::StructDef(def) => sema.to_def(def)?.ty(sema.db),
+        ast::AdtDef::EnumDef(def) => sema.to_def(def)?.ty(sema.db),
+        ast::AdtDef::UnionDef(def) => sema.to_def(def)?.ty(sema.db),
     };
 
     let impls = ImplDef::all_in_crate(sema.db, krate);
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index dc9192d42..0fede0d87 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -487,8 +487,12 @@ impl Analysis {
     }
 
     /// Computes the set of diagnostics for the given file.
-    pub fn diagnostics(&self, file_id: FileId) -> Cancelable<Vec<Diagnostic>> {
-        self.with_db(|db| diagnostics::diagnostics(db, file_id))
+    pub fn diagnostics(
+        &self,
+        file_id: FileId,
+        enable_experimental: bool,
+    ) -> Cancelable<Vec<Diagnostic>> {
+        self.with_db(|db| diagnostics::diagnostics(db, file_id, enable_experimental))
     }
 
     /// Returns the edit required to rename reference at the position to the new
@@ -505,9 +509,11 @@ impl Analysis {
         &self,
         query: &str,
         parse_only: bool,
+        position: FilePosition,
+        selections: Vec<FileRange>,
     ) -> Cancelable<Result<SourceChange, SsrError>> {
         self.with_db(|db| {
-            let edits = ssr::parse_search_replace(query, parse_only, db)?;
+            let edits = ssr::parse_search_replace(query, parse_only, db, position, selections)?;
             Ok(SourceChange::from(edits))
         })
     }
diff --git a/crates/ra_ide/src/runnables.rs b/crates/ra_ide/src/runnables.rs
index 95a35a28d..45e0a7d85 100644
--- a/crates/ra_ide/src/runnables.rs
+++ b/crates/ra_ide/src/runnables.rs
@@ -220,15 +220,7 @@ fn runnable_mod(
     module: ast::Module,
     file_id: FileId,
 ) -> Option<Runnable> {
-    let has_test_function = module
-        .item_list()?
-        .items()
-        .filter_map(|it| match it {
-            ast::ModuleItem::FnDef(it) => Some(it),
-            _ => None,
-        })
-        .any(|f| has_test_related_attribute(&f));
-    if !has_test_function {
+    if !has_test_function_or_multiple_test_submodules(&module) {
         return None;
     }
     let module_def = sema.to_def(&module)?;
@@ -246,6 +238,34 @@ fn runnable_mod(
     Some(Runnable { nav, kind: RunnableKind::TestMod { path }, cfg_exprs })
 }
 
+// We could create runnables for modules with number_of_test_submodules > 0,
+// but that bloats the runnables for no real benefit, since all tests can be run by the submodule already
+fn has_test_function_or_multiple_test_submodules(module: &ast::Module) -> bool {
+    if let Some(item_list) = module.item_list() {
+        let mut number_of_test_submodules = 0;
+
+        for item in item_list.items() {
+            match item {
+                ast::ModuleItem::FnDef(f) => {
+                    if has_test_related_attribute(&f) {
+                        return true;
+                    }
+                }
+                ast::ModuleItem::Module(submodule) => {
+                    if has_test_function_or_multiple_test_submodules(&submodule) {
+                        number_of_test_submodules += 1;
+                    }
+                }
+                _ => (),
+            }
+        }
+
+        number_of_test_submodules > 1
+    } else {
+        false
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use expect::{expect, Expect};
@@ -571,19 +591,33 @@ mod test_mod {
     }
 
     #[test]
-    fn test_runnables_one_depth_layer_module() {
+    fn only_modules_with_test_functions_or_more_than_one_test_submodule_have_runners() {
         check(
             r#"
 //- /lib.rs
 <|>
-mod foo {
-    mod test_mod {
-        #[test]
-        fn test_foo1() {}
+mod root_tests {
+    mod nested_tests_0 {
+        mod nested_tests_1 {
+            #[test]
+            fn nested_test_11() {}
+
+            #[test]
+            fn nested_test_12() {}
+        }
+
+        mod nested_tests_2 {
+            #[test]
+            fn nested_test_2() {}
+        }
+
+        mod nested_tests_3 {}
     }
+
+    mod nested_tests_4 {}
 }
 "#,
-            &[&TEST, &TEST],
+            &[&TEST, &TEST, &TEST, &TEST, &TEST, &TEST],
             expect![[r#"
                 [
                     Runnable {
@@ -591,18 +625,18 @@ mod foo {
                             file_id: FileId(
                                 1,
                             ),
-                            full_range: 15..77,
+                            full_range: 22..323,
                             focus_range: Some(
-                                19..27,
+                                26..40,
                             ),
-                            name: "test_mod",
+                            name: "nested_tests_0",
                             kind: MODULE,
                             container_name: None,
                             description: None,
                             docs: None,
                         },
                         kind: TestMod {
-                            path: "foo::test_mod",
+                            path: "root_tests::nested_tests_0",
                         },
                         cfg_exprs: [],
                     },
@@ -611,11 +645,31 @@ mod foo {
                             file_id: FileId(
                                 1,
                             ),
-                            full_range: 38..71,
+                            full_range: 51..192,
                             focus_range: Some(
-                                57..66,
+                                55..69,
                             ),
-                            name: "test_foo1",
+                            name: "nested_tests_1",
+                            kind: MODULE,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "root_tests::nested_tests_0::nested_tests_1",
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 84..126,
+                            focus_range: Some(
+                                107..121,
+                            ),
+                            name: "nested_test_11",
                             kind: FN_DEF,
                             container_name: None,
                             description: None,
@@ -623,7 +677,7 @@ mod foo {
                         },
                         kind: Test {
                             test_id: Path(
-                                "foo::test_mod::test_foo1",
+                                "root_tests::nested_tests_0::nested_tests_1::nested_test_11",
                             ),
                             attr: TestAttr {
                                 ignore: false,
@@ -631,46 +685,48 @@ mod foo {
                         },
                         cfg_exprs: [],
                     },
-                ]
-            "#]],
-        );
-    }
-
-    #[test]
-    fn test_runnables_multiple_depth_module() {
-        check(
-            r#"
-//- /lib.rs
-<|>
-mod foo {
-    mod bar {
-        mod test_mod {
-            #[test]
-            fn test_foo1() {}
-        }
-    }
-}
-"#,
-            &[&TEST, &TEST],
-            expect![[r#"
-                [
                     Runnable {
                         nav: NavigationTarget {
                             file_id: FileId(
                                 1,
                             ),
-                            full_range: 33..107,
+                            full_range: 140..182,
                             focus_range: Some(
-                                37..45,
+                                163..177,
                             ),
-                            name: "test_mod",
+                            name: "nested_test_12",
+                            kind: FN_DEF,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "root_tests::nested_tests_0::nested_tests_1::nested_test_12",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 202..286,
+                            focus_range: Some(
+                                206..220,
+                            ),
+                            name: "nested_tests_2",
                             kind: MODULE,
                             container_name: None,
                             description: None,
                             docs: None,
                         },
                         kind: TestMod {
-                            path: "foo::bar::test_mod",
+                            path: "root_tests::nested_tests_0::nested_tests_2",
                         },
                         cfg_exprs: [],
                     },
@@ -679,11 +735,11 @@ mod foo {
                             file_id: FileId(
                                 1,
                             ),
-                            full_range: 60..97,
+                            full_range: 235..276,
                             focus_range: Some(
-                                83..92,
+                                258..271,
                             ),
-                            name: "test_foo1",
+                            name: "nested_test_2",
                             kind: FN_DEF,
                             container_name: None,
                             description: None,
@@ -691,7 +747,7 @@ mod foo {
                         },
                         kind: Test {
                             test_id: Path(
-                                "foo::bar::test_mod::test_foo1",
+                                "root_tests::nested_tests_0::nested_tests_2::nested_test_2",
                             ),
                             attr: TestAttr {
                                 ignore: false,
diff --git a/crates/ra_ide/src/ssr.rs b/crates/ra_ide/src/ssr.rs
index b3e9e5dfe..4348b43be 100644
--- a/crates/ra_ide/src/ssr.rs
+++ b/crates/ra_ide/src/ssr.rs
@@ -1,5 +1,5 @@
-use ra_db::SourceDatabaseExt;
-use ra_ide_db::{symbol_index::SymbolsDatabase, RootDatabase};
+use ra_db::{FilePosition, FileRange};
+use ra_ide_db::RootDatabase;
 
 use crate::SourceFileEdit;
 use ra_ssr::{MatchFinder, SsrError, SsrRule};
@@ -11,6 +11,22 @@ use ra_ssr::{MatchFinder, SsrError, SsrRule};
 // A `$<name>` placeholder in the search pattern will match any AST node and `$<name>` will reference it in the replacement.
 // Within a macro call, a placeholder will match up until whatever token follows the placeholder.
 //
+// All paths in both the search pattern and the replacement template must resolve in the context
+// in which this command is invoked. Paths in the search pattern will then match the code if they
+// resolve to the same item, even if they're written differently. For example if we invoke the
+// command in the module `foo` with a pattern of `Bar`, then code in the parent module that refers
+// to `foo::Bar` will match.
+//
+// Paths in the replacement template will be rendered appropriately for the context in which the
+// replacement occurs. For example if our replacement template is `foo::Bar` and we match some
+// code in the `foo` module, we'll insert just `Bar`.
+//
+// Method calls should generally be written in UFCS form. e.g. `foo::Bar::baz($s, $a)` will match
+// `$s.baz($a)`, provided the method call `baz` resolves to the method `foo::Bar::baz`.
+//
+// The scope of the search / replace will be restricted to the current selection if any, otherwise
+// it will apply to the whole workspace.
+//
 // Placeholders may be given constraints by writing them as `${<name>:<constraint1>:<constraint2>...}`.
 //
 // Supported constraints:
@@ -43,21 +59,14 @@ pub fn parse_search_replace(
     rule: &str,
     parse_only: bool,
     db: &RootDatabase,
+    resolve_context: FilePosition,
+    selections: Vec<FileRange>,
 ) -> Result<Vec<SourceFileEdit>, SsrError> {
-    let mut edits = vec![];
     let rule: SsrRule = rule.parse()?;
+    let mut match_finder = MatchFinder::in_context(db, resolve_context, selections);
+    match_finder.add_rule(rule)?;
     if parse_only {
-        return Ok(edits);
-    }
-    let mut match_finder = MatchFinder::new(db);
-    match_finder.add_rule(rule);
-    for &root in db.local_roots().iter() {
-        let sr = db.source_root(root);
-        for file_id in sr.iter() {
-            if let Some(edit) = match_finder.edits_for_file(file_id) {
-                edits.push(SourceFileEdit { file_id, edit });
-            }
-        }
+        return Ok(Vec::new());
     }
-    Ok(edits)
+    Ok(match_finder.edits())
 }
diff --git a/crates/ra_ide/src/syntax_highlighting/html.rs b/crates/ra_ide/src/syntax_highlighting/html.rs
index 0be55bca9..a5e7d2867 100644
--- a/crates/ra_ide/src/syntax_highlighting/html.rs
+++ b/crates/ra_ide/src/syntax_highlighting/html.rs
@@ -1,5 +1,6 @@
 //! Renders a bit of code as HTML.
 
+use oorandom::Rand32;
 use ra_db::SourceDatabase;
 use ra_syntax::{AstNode, TextRange, TextSize};
 
@@ -9,13 +10,12 @@ pub(crate) fn highlight_as_html(db: &RootDatabase, file_id: FileId, rainbow: boo
     let parse = db.parse(file_id);
 
     fn rainbowify(seed: u64) -> String {
-        use rand::prelude::*;
-        let mut rng = SmallRng::seed_from_u64(seed);
+        let mut rng = Rand32::new(seed);
         format!(
             "hsl({h},{s}%,{l}%)",
-            h = rng.gen_range::<u16, _, _>(0, 361),
-            s = rng.gen_range::<u16, _, _>(42, 99),
-            l = rng.gen_range::<u16, _, _>(40, 91),
+            h = rng.rand_range(0..361),
+            s = rng.rand_range(42..99),
+            l = rng.rand_range(40..91),
         )
     }
 
diff --git a/crates/ra_ide/test_data/rainbow_highlighting.html b/crates/ra_ide/test_data/rainbow_highlighting.html
index 08d83302c..401e87a73 100644
--- a/crates/ra_ide/test_data/rainbow_highlighting.html
+++ b/crates/ra_ide/test_data/rainbow_highlighting.html
@@ -36,14 +36,14 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
 </style>
 <pre><code><span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
-    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="8121853618659664005" style="color: hsl(261,57%,61%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
-    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="2705725358298919760" style="color: hsl(17,51%,74%);">x</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(261,57%,61%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
-    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="3365759661443752373" style="color: hsl(127,76%,66%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(261,57%,61%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="2705725358298919760" style="color: hsl(76,47%,83%);">x</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="3365759661443752373" style="color: hsl(15,86%,51%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
 
-    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="794745962933817518" style="color: hsl(19,74%,76%);">x</span> <span class="operator">=</span> <span class="string_literal">"other color please!"</span><span class="punctuation">;</span>
-    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="6717528807933952652" style="color: hsl(85,49%,84%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="794745962933817518" style="color: hsl(19,74%,76%);">x</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="794745962933817518" style="color: hsl(127,71%,87%);">x</span> <span class="operator">=</span> <span class="string_literal">"other color please!"</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="6717528807933952652" style="color: hsl(90,74%,79%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="794745962933817518" style="color: hsl(127,71%,87%);">x</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
 <span class="punctuation">}</span>
 
 <span class="keyword">fn</span> <span class="function declaration">bar</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
-    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable" data-binding-hash="8121853618659664005" style="color: hsl(261,57%,61%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
 <span class="punctuation">}</span></code></pre>
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