13 files changed, 245 insertions, 32 deletions

diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index 0c950003e..02e17ba43 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -25,7 +25,7 @@ use crate::{diagnostics::Fix, references::rename::rename_with_semantics, FilePos
 /// A [Diagnostic] that potentially has a fix available.
 ///
 /// [Diagnostic]: hir::diagnostics::Diagnostic
-pub trait DiagnosticWithFix: Diagnostic {
+pub(crate) trait DiagnosticWithFix: Diagnostic {
     fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix>;
 }
 
diff --git a/crates/ide/src/doc_links.rs b/crates/ide/src/doc_links.rs
index 250f10f9f..10263537a 100644
--- a/crates/ide/src/doc_links.rs
+++ b/crates/ide/src/doc_links.rs
@@ -1,7 +1,6 @@
 //! Resolves and rewrites links in markdown documentation.
 
-use std::convert::TryFrom;
-use std::iter::once;
+use std::{convert::TryFrom, iter::once};
 
 use itertools::Itertools;
 use pulldown_cmark::{BrokenLink, CowStr, Event, InlineStr, LinkType, Options, Parser, Tag};
@@ -21,10 +20,10 @@ use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset,
 
 use crate::{FilePosition, Semantics};
 
-pub type DocumentationLink = String;
+pub(crate) type DocumentationLink = String;
 
 /// Rewrite documentation links in markdown to point to an online host (e.g. docs.rs)
-pub fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition) -> String {
+pub(crate) fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition) -> String {
     let mut cb = |link: BrokenLink| {
         Some((
             /*url*/ link.reference.to_owned().into(),
@@ -63,7 +62,7 @@ pub fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition)
 }
 
 /// Remove all links in markdown documentation.
-pub fn remove_links(markdown: &str) -> String {
+pub(crate) fn remove_links(markdown: &str) -> String {
     let mut drop_link = false;
 
     let mut opts = Options::empty();
diff --git a/crates/ide/src/file_structure.rs b/crates/ide/src/file_structure.rs
index 6168fb837..415795e8c 100644
--- a/crates/ide/src/file_structure.rs
+++ b/crates/ide/src/file_structure.rs
@@ -27,7 +27,7 @@ pub struct StructureNode {
 //
 // | VS Code | kbd:[Ctrl+Shift+O]
 // |===
-pub fn file_structure(file: &SourceFile) -> Vec<StructureNode> {
+pub(crate) fn file_structure(file: &SourceFile) -> Vec<StructureNode> {
     let mut res = Vec::new();
     let mut stack = Vec::new();
 
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 49d8e4ae1..ac704ae21 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -1,6 +1,6 @@
 use assists::utils::FamousDefs;
 use either::Either;
-use hir::{known, HirDisplay, Semantics};
+use hir::{known, Callable, HirDisplay, Semantics};
 use ide_db::RootDatabase;
 use stdx::to_lower_snake_case;
 use syntax::{
@@ -170,7 +170,7 @@ fn get_param_name_hints(
             };
             Some((param_name, arg))
         })
-        .filter(|(param_name, arg)| should_show_param_name_hint(sema, &callable, &param_name, &arg))
+        .filter(|(param_name, arg)| should_show_param_name_hint(sema, &callable, param_name, &arg))
         .map(|(param_name, arg)| InlayHint {
             range: arg.syntax().text_range(),
             kind: InlayKind::ParameterHint,
@@ -334,9 +334,11 @@ fn should_show_param_name_hint(
         | hir::CallableKind::TupleEnumVariant(_)
         | hir::CallableKind::Closure => None,
     };
+
     if param_name.is_empty()
         || Some(param_name) == fn_name.as_ref().map(|s| s.trim_start_matches('_'))
         || is_argument_similar_to_param_name(sema, argument, param_name)
+        || is_param_name_similar_to_fn_name(param_name, callable, fn_name.as_ref())
         || param_name.starts_with("ra_fixture")
     {
         return false;
@@ -364,6 +366,26 @@ fn is_argument_similar_to_param_name(
     }
 }
 
+fn is_param_name_similar_to_fn_name(
+    param_name: &str,
+    callable: &Callable,
+    fn_name: Option<&String>,
+) -> bool {
+    // if it's the only parameter, don't show it if:
+    // - is the same as the function name, or
+    // - the function ends with '_' + param_name
+
+    match (callable.n_params(), fn_name) {
+        (1, Some(function)) => {
+            function == param_name
+                || (function.len() > param_name.len()
+                    && function.ends_with(param_name)
+                    && function[..function.len() - param_name.len()].ends_with('_'))
+        }
+        _ => false,
+    }
+}
+
 fn is_enum_name_similar_to_param_name(
     sema: &Semantics<RootDatabase>,
     argument: &ast::Expr,
@@ -457,6 +479,88 @@ fn main() {
     }
 
     #[test]
+    fn param_name_similar_to_fn_name_still_hints() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn max(x: i32, y: i32) -> i32 { x + y }
+fn main() {
+    let _x = max(
+        4,
+      //^ x
+        4,
+      //^ y
+    );
+}"#,
+        );
+    }
+
+    #[test]
+    fn param_name_similar_to_fn_name() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn param_with_underscore(with_underscore: i32) -> i32 { with_underscore }
+fn main() {
+    let _x = param_with_underscore(
+        4,
+    );
+}"#,
+        );
+    }
+
+    #[test]
+    fn param_name_same_as_fn_name() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn foo(foo: i32) -> i32 { foo }
+fn main() {
+    let _x = foo(
+        4,
+    );
+}"#,
+        );
+    }
+
+    #[test]
+    fn never_hide_param_when_multiple_params() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn foo(bar: i32, baz: i32) -> i32 { bar + baz }
+fn main() {
+    let _x = foo(
+        4,
+      //^ bar
+        8,
+      //^ baz
+    );
+}"#,
+        );
+    }
+
+    #[test]
     fn hints_disabled() {
         check_with_config(
             InlayHintsConfig {
@@ -1235,4 +1339,25 @@ fn main() {
 "#,
         );
     }
+
+    #[test]
+    fn infer_call_method_return_associated_types_with_generic() {
+        check(
+            r#"
+            pub trait Default {
+                fn default() -> Self;
+            }
+            pub trait Foo {
+                type Bar: Default;
+            }
+
+            pub fn quux<T: Foo>() -> T::Bar {
+                let y = Default::default();
+                  //^ <T as Foo>::Bar
+
+                y
+            }
+            "#,
+        );
+    }
 }
diff --git a/crates/ide/src/join_lines.rs b/crates/ide/src/join_lines.rs
index e37702acd..b5a6f66fd 100644
--- a/crates/ide/src/join_lines.rs
+++ b/crates/ide/src/join_lines.rs
@@ -18,7 +18,7 @@ use text_edit::{TextEdit, TextEditBuilder};
 //
 // | VS Code | **Rust Analyzer: Join lines**
 // |===
-pub fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
+pub(crate) fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
     let range = if range.is_empty() {
         let syntax = file.syntax();
         let text = syntax.text().slice(range.start()..);
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 4bc733b70..6288f7ea7 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -72,18 +72,20 @@ pub use crate::{
     inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
     markup::Markup,
     prime_caches::PrimeCachesProgress,
-    references::{
-        Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult, RenameError,
-    },
+    references::{rename::RenameError, Declaration, ReferenceSearchResult},
     runnables::{Runnable, RunnableKind, TestId},
     syntax_highlighting::{
-        Highlight, HighlightModifier, HighlightModifiers, HighlightTag, HighlightedRange,
+        tags::{Highlight, HighlightModifier, HighlightModifiers, HighlightTag},
+        HighlightedRange,
     },
 };
 pub use completion::{
     CompletionConfig, CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat,
 };
-pub use ide_db::call_info::CallInfo;
+pub use ide_db::{
+    call_info::CallInfo,
+    search::{Reference, ReferenceAccess, ReferenceKind},
+};
 
 pub use assists::{
     utils::MergeBehaviour, Assist, AssistConfig, AssistId, AssistKind, ResolvedAssist,
@@ -503,7 +505,7 @@ impl Analysis {
         position: FilePosition,
         new_name: &str,
     ) -> Cancelable<Result<RangeInfo<SourceChange>, RenameError>> {
-        self.with_db(|db| references::rename(db, position, new_name))
+        self.with_db(|db| references::rename::rename(db, position, new_name))
     }
 
     pub fn structural_search_replace(
diff --git a/crates/ide/src/markdown_remove.rs b/crates/ide/src/markdown_remove.rs
index 02ad39dfb..3ec5c629e 100644
--- a/crates/ide/src/markdown_remove.rs
+++ b/crates/ide/src/markdown_remove.rs
@@ -1,11 +1,10 @@
 //! Removes markdown from strings.
-
 use pulldown_cmark::{Event, Parser, Tag};
 
 /// Removes all markdown, keeping the text and code blocks
 ///
 /// Currently limited in styling, i.e. no ascii tables or lists
-pub fn remove_markdown(markdown: &str) -> String {
+pub(crate) fn remove_markdown(markdown: &str) -> String {
     let mut out = String::new();
     let parser = Parser::new(markdown);
 
diff --git a/crates/ide/src/matching_brace.rs b/crates/ide/src/matching_brace.rs
index cb6abb0db..d70248afe 100644
--- a/crates/ide/src/matching_brace.rs
+++ b/crates/ide/src/matching_brace.rs
@@ -15,7 +15,7 @@ use test_utils::mark;
 //
 // | VS Code | **Rust Analyzer: Find matching brace**
 // |===
-pub fn matching_brace(file: &SourceFile, offset: TextSize) -> Option<TextSize> {
+pub(crate) fn matching_brace(file: &SourceFile, offset: TextSize) -> Option<TextSize> {
     const BRACES: &[SyntaxKind] =
         &[T!['{'], T!['}'], T!['['], T![']'], T!['('], T![')'], T![<], T![>], T![|], T![|]];
     let (brace_token, brace_idx) = file
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
index a517081d5..e05465b32 100644
--- a/crates/ide/src/references.rs
+++ b/crates/ide/src/references.rs
@@ -14,7 +14,8 @@ pub(crate) mod rename;
 use hir::Semantics;
 use ide_db::{
     defs::{Definition, NameClass, NameRefClass},
-    search::SearchScope,
+    search::Reference,
+    search::{ReferenceAccess, ReferenceKind, SearchScope},
     RootDatabase,
 };
 use syntax::{
@@ -25,11 +26,6 @@ use syntax::{
 
 use crate::{display::TryToNav, FilePosition, FileRange, NavigationTarget, RangeInfo};
 
-pub(crate) use self::rename::rename;
-pub use self::rename::RenameError;
-
-pub use ide_db::search::{Reference, ReferenceAccess, ReferenceKind};
-
 #[derive(Debug, Clone)]
 pub struct ReferenceSearchResult {
     declaration: Declaration,
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index eb82456ad..2bd0e86e5 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -102,6 +102,7 @@ pub(crate) fn runnable(
 ) -> Option<Runnable> {
     match_ast! {
         match item {
+            ast::Struct(it) => runnable_struct(sema, it, file_id),
             ast::Fn(it) => runnable_fn(sema, it, file_id),
             ast::Module(it) => runnable_mod(sema, it, file_id),
             _ => None,
@@ -182,6 +183,43 @@ fn runnable_fn(
     Some(Runnable { nav, kind, cfg })
 }
 
+fn runnable_struct(
+    sema: &Semantics<RootDatabase>,
+    struct_def: ast::Struct,
+    file_id: FileId,
+) -> Option<Runnable> {
+    if !has_runnable_doc_test(&struct_def) {
+        return None;
+    }
+    let name_string = struct_def.name()?.text().to_string();
+
+    let attrs =
+        Attrs::from_attrs_owner(sema.db, InFile::new(HirFileId::from(file_id), &struct_def));
+    let cfg = attrs.cfg();
+
+    let test_id = match sema.to_def(&struct_def).map(|def| def.module(sema.db)) {
+        Some(module) => {
+            let path_iter = module
+                .path_to_root(sema.db)
+                .into_iter()
+                .rev()
+                .filter_map(|it| it.name(sema.db))
+                .map(|name| name.to_string());
+            let path = path_iter.chain(std::iter::once(name_string)).join("::");
+
+            TestId::Path(path)
+        }
+        None => TestId::Name(name_string),
+    };
+
+    let nav = NavigationTarget::from_doc_commented(
+        sema.db,
+        InFile::new(file_id.into(), &struct_def),
+        InFile::new(file_id.into(), &struct_def),
+    );
+    Some(Runnable { nav, kind: RunnableKind::DocTest { test_id }, cfg })
+}
+
 #[derive(Debug, Copy, Clone)]
 pub struct TestAttr {
     pub ignore: bool,
@@ -215,8 +253,8 @@ const RUSTDOC_FENCE: &str = "```";
 const RUSTDOC_CODE_BLOCK_ATTRIBUTES_RUNNABLE: &[&str] =
     &["", "rust", "should_panic", "edition2015", "edition2018"];
 
-fn has_runnable_doc_test(fn_def: &ast::Fn) -> bool {
-    fn_def.doc_comment_text().map_or(false, |comments_text| {
+fn has_runnable_doc_test(def: &dyn DocCommentsOwner) -> bool {
+    def.doc_comment_text().map_or(false, |comments_text| {
         let mut in_code_block = false;
 
         for line in comments_text.lines() {
@@ -487,8 +525,14 @@ fn should_have_no_runnable_5() {}
 /// let z = 55;
 /// ```
 fn should_have_no_runnable_6() {}
+
+/// ```
+/// let x = 5;
+/// ```
+struct StructWithRunnable(String);
+
 "#,
-            &[&BIN, &DOCTEST, &DOCTEST, &DOCTEST],
+            &[&BIN, &DOCTEST, &DOCTEST, &DOCTEST, &DOCTEST],
             expect![[r#"
                 [
                     Runnable {
@@ -569,6 +613,26 @@ fn should_have_no_runnable_6() {}
                         },
                         cfg: None,
                     },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                0,
+                            ),
+                            full_range: 756..821,
+                            focus_range: None,
+                            name: "StructWithRunnable",
+                            kind: STRUCT,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: DocTest {
+                            test_id: Path(
+                                "StructWithRunnable",
+                            ),
+                        },
+                        cfg: None,
+                    },
                 ]
             "#]],
         );
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 9f864179e..efcc8ecfe 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -2,7 +2,7 @@ mod format;
 mod html;
 mod injection;
 mod macro_rules;
-mod tags;
+pub(crate) mod tags;
 #[cfg(test)]
 mod tests;
 
@@ -20,12 +20,13 @@ use syntax::{
 };
 
 use crate::{
-    syntax_highlighting::{format::FormatStringHighlighter, macro_rules::MacroRulesHighlighter},
-    FileId,
+    syntax_highlighting::{
+        format::FormatStringHighlighter, macro_rules::MacroRulesHighlighter, tags::Highlight,
+    },
+    FileId, HighlightModifier, HighlightTag,
 };
 
 pub(crate) use html::highlight_as_html;
-pub use tags::{Highlight, HighlightModifier, HighlightModifiers, HighlightTag};
 
 #[derive(Debug, Clone)]
 pub struct HighlightedRange {
@@ -562,6 +563,9 @@ fn highlight_element(
             T![!] if element.parent().and_then(ast::MacroCall::cast).is_some() => {
                 HighlightTag::Macro.into()
             }
+            T![!] if element.parent().and_then(ast::NeverType::cast).is_some() => {
+                HighlightTag::BuiltinType.into()
+            }
             T![*] if element.parent().and_then(ast::PtrType::cast).is_some() => {
                 HighlightTag::Keyword.into()
             }
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index c6b4f5a00..5eb222ee2 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -110,11 +110,21 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="function">foo</span><span class="operator">::</span><span class="punctuation">&lt;</span><span class="lifetime">'a</span><span class="punctuation">,</span> <span class="builtin_type">i32</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span>
 <span class="punctuation">}</span>
 
+<span class="keyword">fn</span> <span class="function declaration">never</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">!</span> <span class="punctuation">{</span>
+    <span class="keyword control">loop</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
 <span class="keyword">use</span> <span class="module">ops</span><span class="operator">::</span><span class="trait">Fn</span><span class="punctuation">;</span>
 <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">&lt;</span><span class="type_param declaration">F</span><span class="punctuation">:</span> <span class="trait">Fn</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="value_param declaration callable">f</span><span class="punctuation">:</span> <span class="type_param">F</span><span class="punctuation">)</span> <span class="punctuation">{</span>
     <span class="value_param callable">f</span><span class="punctuation">(</span><span class="punctuation">)</span>
 <span class="punctuation">}</span>
 
+<span class="keyword">fn</span> <span class="function declaration">foobar</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="keyword">impl</span> <span class="unresolved_reference">Copy</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">let</span> <span class="variable declaration">bar</span> <span class="operator">=</span> <span class="function">foobar</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
 <span class="macro">macro_rules!</span> <span class="macro declaration">def_fn</span> <span class="punctuation">{</span>
     <span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">}</span>
 <span class="punctuation">}</span>
@@ -179,6 +189,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
     <span class="keyword">let</span> <span class="variable declaration">baz</span> <span class="operator">=</span> <span class="numeric_literal">-</span><span class="numeric_literal">42</span><span class="punctuation">;</span>
     <span class="keyword">let</span> <span class="variable declaration">baz</span> <span class="operator">=</span> <span class="operator">-</span><span class="variable">baz</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="punctuation">_</span> <span class="operator">=</span> <span class="operator">!</span><span class="bool_literal">true</span><span class="punctuation">;</span>
 <span class="punctuation">}</span>
 
 <span class="keyword">enum</span> <span class="enum declaration">Option</span><span class="punctuation">&lt;</span><span class="type_param declaration">T</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index dd43f9dd9..2b667b0d4 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -84,11 +84,21 @@ fn foo<'a, T>() -> T {
     foo::<'a, i32>()
 }
 
+fn never() -> ! {
+    loop {}
+}
+
 use ops::Fn;
 fn baz<F: Fn() -> ()>(f: F) {
     f()
 }
 
+fn foobar() -> impl Copy {}
+
+fn foo() {
+    let bar = foobar();
+}
+
 macro_rules! def_fn {
     ($($tt:tt)*) => {$($tt)*}
 }
@@ -153,6 +163,8 @@ fn main() {
 
     let baz = -42;
     let baz = -baz;
+
+    let _ = !true;
 }
 
 enum Option<T> {