Add qualify path assist

1 files changed, 1020 insertions, 0 deletions

diff --git a/crates/assists/src/handlers/qualify_path.rs b/crates/assists/src/handlers/qualify_path.rs
new file mode 100644
index 000000000..cff207889
--- /dev/null
+++ b/crates/assists/src/handlers/qualify_path.rs
@@ -0,0 +1,1020 @@
+use std::collections::BTreeSet;
+
+use syntax::{ast, AstNode, TextRange};
+
+use crate::{
+    assist_context::{AssistContext, Assists},
+    utils::import_assets::{ImportAssets, ImportCandidate},
+    utils::mod_path_to_ast,
+    AssistId, AssistKind, GroupLabel,
+};
+
+// Assist: qualify_path
+//
+// If the name is unresolved, provides all possible qualified paths for it.
+//
+// ```
+// fn main() {
+//     let map = HashMap<|>::new();
+// }
+// # pub mod std { pub mod collections { pub struct HashMap { } } }
+// ```
+// ->
+// ```
+// fn main() {
+//     let map = std::collections::HashMap::new();
+// }
+// # pub mod std { pub mod collections { pub struct HashMap { } } }
+// ```
+pub(crate) fn qualify_path(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let import_assets =
+        if let Some(path_under_caret) = ctx.find_node_at_offset_with_descend::<ast::Path>() {
+            ImportAssets::for_regular_path(path_under_caret, &ctx.sema)
+        } else if let Some(method_under_caret) =
+            ctx.find_node_at_offset_with_descend::<ast::MethodCallExpr>()
+        {
+            ImportAssets::for_method_call(method_under_caret, &ctx.sema)
+        } else {
+            None
+        }?;
+    let proposed_imports = import_assets.search_for_relative_paths(&ctx.sema);
+    if proposed_imports.is_empty() {
+        return None;
+    }
+
+    let range = ctx.sema.original_range(import_assets.syntax_under_caret()).range;
+    match import_assets.import_candidate() {
+        ImportCandidate::QualifierStart(candidate) => {
+            let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
+            let segment = path.segment()?;
+            qualify_path_qualifier_start(acc, proposed_imports, range, segment, &candidate.name)
+        }
+        ImportCandidate::UnqualifiedName(candidate) => {
+            qualify_path_unqualified_name(acc, proposed_imports, range, &candidate.name)
+        }
+        ImportCandidate::TraitAssocItem(candidate) => {
+            let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
+            let (qualifier, segment) = (path.qualifier()?, path.segment()?);
+            qualify_path_trait_assoc_item(
+                acc,
+                proposed_imports,
+                range,
+                qualifier,
+                segment,
+                &candidate.name,
+            )
+        }
+        ImportCandidate::TraitMethod(candidate) => {
+            let mcall_expr = ast::MethodCallExpr::cast(import_assets.syntax_under_caret().clone())?;
+            let receiver = mcall_expr.receiver()?;
+            let name_ref = mcall_expr.name_ref()?;
+            qualify_path_trait_method(
+                acc,
+                proposed_imports,
+                range,
+                receiver,
+                name_ref,
+                &candidate.name,
+            )
+        }
+    };
+    Some(())
+}
+
+// a test that covers this -> `associated_struct_const`
+fn qualify_path_qualifier_start(
+    acc: &mut Assists,
+    proposed_imports: BTreeSet<hir::ModPath>,
+    range: TextRange,
+    segment: ast::PathSegment,
+    qualifier_start: &str,
+) {
+    let group_label = GroupLabel(format!("Qualify {}", qualifier_start));
+    for import in proposed_imports {
+        acc.add_group(
+            &group_label,
+            AssistId("qualify_path", AssistKind::QuickFix),
+            format!("Qualify with `{}`", &import),
+            range,
+            |builder| {
+                let import = mod_path_to_ast(&import);
+                builder.replace(range, format!("{}::{}", import, segment));
+            },
+        );
+    }
+}
+
+// a test that covers this -> `applicable_when_found_an_import_partial`
+fn qualify_path_unqualified_name(
+    acc: &mut Assists,
+    proposed_imports: BTreeSet<hir::ModPath>,
+    range: TextRange,
+    name: &str,
+) {
+    let group_label = GroupLabel(format!("Qualify {}", name));
+    for import in proposed_imports {
+        acc.add_group(
+            &group_label,
+            AssistId("qualify_path", AssistKind::QuickFix),
+            format!("Qualify as `{}`", &import),
+            range,
+            |builder| builder.replace(range, mod_path_to_ast(&import).to_string()),
+        );
+    }
+}
+
+// a test that covers this -> `associated_trait_const`
+fn qualify_path_trait_assoc_item(
+    acc: &mut Assists,
+    proposed_imports: BTreeSet<hir::ModPath>,
+    range: TextRange,
+    qualifier: ast::Path,
+    segment: ast::PathSegment,
+    trait_assoc_item_name: &str,
+) {
+    let group_label = GroupLabel(format!("Qualify {}", trait_assoc_item_name));
+    for import in proposed_imports {
+        acc.add_group(
+            &group_label,
+            AssistId("qualify_path", AssistKind::QuickFix),
+            format!("Qualify with cast as `{}`", &import),
+            range,
+            |builder| {
+                let import = mod_path_to_ast(&import);
+                builder.replace(range, format!("<{} as {}>::{}", qualifier, import, segment));
+            },
+        );
+    }
+}
+
+// a test that covers this -> `trait_method`
+fn qualify_path_trait_method(
+    acc: &mut Assists,
+    proposed_imports: BTreeSet<hir::ModPath>,
+    range: TextRange,
+    receiver: ast::Expr,
+    name_ref: ast::NameRef,
+    trait_method_name: &str,
+) {
+    let group_label = GroupLabel(format!("Qualify {}", trait_method_name));
+    for import in proposed_imports {
+        acc.add_group(
+            &group_label,
+            AssistId("qualify_path", AssistKind::QuickFix), // < Does this still count as quickfix?
+            format!("Qualify `{}`", &import),
+            range,
+            |builder| {
+                let import = mod_path_to_ast(&import);
+                // TODO: check the receiver self type and emit refs accordingly, don't discard other function parameters
+                builder.replace(range, format!("{}::{}(&{})", import, name_ref, receiver));
+            },
+        );
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
+    #[test]
+    fn applicable_when_found_an_import_partial() {
+        check_assist(
+            qualify_path,
+            r"
+            mod std {
+                pub mod fmt {
+                    pub struct Formatter;
+                }
+            }
+
+            use std::fmt;
+
+            <|>Formatter
+            ",
+            r"
+            mod std {
+                pub mod fmt {
+                    pub struct Formatter;
+                }
+            }
+
+            use std::fmt;
+
+            fmt::Formatter
+            ",
+        );
+    }
+
+    #[test]
+    fn applicable_when_found_an_import() {
+        check_assist(
+            qualify_path,
+            r"
+            <|>PubStruct
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            PubMod::PubStruct
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn applicable_in_macros() {
+        check_assist(
+            qualify_path,
+            r"
+            macro_rules! foo {
+                ($i:ident) => { fn foo(a: $i) {} }
+            }
+            foo!(Pub<|>Struct);
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            macro_rules! foo {
+                ($i:ident) => { fn foo(a: $i) {} }
+            }
+            foo!(PubMod::PubStruct);
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn applicable_when_found_multiple_imports() {
+        check_assist(
+            qualify_path,
+            r"
+            PubSt<|>ruct
+
+            pub mod PubMod1 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod2 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod3 {
+                pub struct PubStruct;
+            }
+            ",
+            r"
+            PubMod3::PubStruct
+
+            pub mod PubMod1 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod2 {
+                pub struct PubStruct;
+            }
+            pub mod PubMod3 {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_already_imported_types() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            use PubMod::PubStruct;
+
+            PubStruct<|>
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_types_with_private_paths() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            PrivateStruct<|>
+
+            pub mod PubMod {
+                struct PrivateStruct;
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_when_no_imports_found() {
+        check_assist_not_applicable(
+            qualify_path,
+            "
+            PubStruct<|>",
+        );
+    }
+
+    #[test]
+    fn not_applicable_in_import_statements() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            use PubStruct<|>;
+
+            pub mod PubMod {
+                pub struct PubStruct;
+            }",
+        );
+    }
+
+    #[test]
+    fn qualify_function() {
+        check_assist(
+            qualify_path,
+            r"
+            test_function<|>
+
+            pub mod PubMod {
+                pub fn test_function() {};
+            }
+            ",
+            r"
+            PubMod::test_function
+
+            pub mod PubMod {
+                pub fn test_function() {};
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn qualify_macro() {
+        check_assist(
+            qualify_path,
+            r"
+//- /lib.rs crate:crate_with_macro
+#[macro_export]
+macro_rules! foo {
+    () => ()
+}
+
+//- /main.rs crate:main deps:crate_with_macro
+fn main() {
+    foo<|>
+}
+",
+            r"
+fn main() {
+    crate_with_macro::foo
+}
+",
+        );
+    }
+
+    #[test]
+    fn qualify_path_target() {
+        check_assist_target(
+            qualify_path,
+            r"
+            struct AssistInfo {
+                group_label: Option<<|>GroupLabel>,
+            }
+
+            mod m { pub struct GroupLabel; }
+            ",
+            "GroupLabel",
+        )
+    }
+
+    #[test]
+    fn not_applicable_when_path_start_is_imported() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            pub mod mod1 {
+                pub mod mod2 {
+                    pub mod mod3 {
+                        pub struct TestStruct;
+                    }
+                }
+            }
+
+            use mod1::mod2;
+            fn main() {
+                mod2::mod3::TestStruct<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_function() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            pub mod test_mod {
+                pub fn test_function() {}
+            }
+
+            use test_mod::test_function;
+            fn main() {
+                test_function<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_struct_function() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    pub fn test_function() {}
+                }
+            }
+
+            fn main() {
+                TestStruct::test_function<|>
+            }
+            ",
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    pub fn test_function() {}
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::test_function
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_struct_const() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                TestStruct::TEST_CONST<|>
+            }
+            ",
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::TEST_CONST
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_trait_function() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::test_function<|>
+            }
+            ",
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+
+            fn main() {
+                <test_mod::TestStruct as test_mod::TestTrait>::test_function
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_function() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub trait TestTrait2 {
+                    fn test_function();
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    fn test_function() {}
+                }
+                impl TestTrait for TestEnum {
+                    fn test_function() {}
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                test_mod::TestEnum::test_function<|>;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn associated_trait_const() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::TEST_CONST<|>
+            }
+            ",
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                <test_mod::TestStruct as test_mod::TestTrait>::TEST_CONST
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_const() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub trait TestTrait2 {
+                    const TEST_CONST: f64;
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    const TEST_CONST: f64 = 42.0;
+                }
+                impl TestTrait for TestEnum {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                test_mod::TestEnum::TEST_CONST<|>;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn trait_method() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            ",
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_mod::TestTrait::test_method(&test_struct)
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn trait_method_multi_params() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self, test: i32);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self, test: i32) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_struct.test_meth<|>od(42)
+            }
+            ",
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self, test: i32);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self, test: i32) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_mod::TestTrait::test_method(&test_struct, 42)
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn trait_method_consume() {
+        check_assist(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            ",
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_mod::TestTrait::test_method(test_struct)
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn trait_method_cross_crate() {
+        check_assist(
+            qualify_path,
+            r"
+            //- /main.rs crate:main deps:dep
+            fn main() {
+                let test_struct = dep::test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            //- /dep.rs crate:dep
+            pub mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+            ",
+            r"
+            fn main() {
+                let test_struct = dep::test_mod::TestStruct {};
+                dep::test_mod::TestTrait::test_method(&test_struct)
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn assoc_fn_cross_crate() {
+        check_assist(
+            qualify_path,
+            r"
+            //- /main.rs crate:main deps:dep
+            fn main() {
+                dep::test_mod::TestStruct::test_func<|>tion
+            }
+            //- /dep.rs crate:dep
+            pub mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+            ",
+            r"
+            fn main() {
+                <dep::test_mod::TestStruct as dep::test_mod::TestTrait>::test_function
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn assoc_const_cross_crate() {
+        check_assist(
+            qualify_path,
+            r"
+            //- /main.rs crate:main deps:dep
+            fn main() {
+                dep::test_mod::TestStruct::CONST<|>
+            }
+            //- /dep.rs crate:dep
+            pub mod test_mod {
+                pub trait TestTrait {
+                    const CONST: bool;
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    const CONST: bool = true;
+                }
+            }
+            ",
+            r"
+            fn main() {
+                <dep::test_mod::TestStruct as dep::test_mod::TestTrait>::CONST
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn assoc_fn_as_method_cross_crate() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            //- /main.rs crate:main deps:dep
+            fn main() {
+                let test_struct = dep::test_mod::TestStruct {};
+                test_struct.test_func<|>tion()
+            }
+            //- /dep.rs crate:dep
+            pub mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn private_trait_cross_crate() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            //- /main.rs crate:main deps:dep
+            fn main() {
+                let test_struct = dep::test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            //- /dep.rs crate:dep
+            pub mod test_mod {
+                trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_method() {
+        check_assist_not_applicable(
+            qualify_path,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub trait TestTrait2 {
+                    fn test_method(&self);
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    fn test_method(&self) {}
+                }
+                impl TestTrait for TestEnum {
+                    fn test_method(&self) {}
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                let one = test_mod::TestEnum::One;
+                one.test<|>_method();
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn dep_import() {
+        check_assist(
+            qualify_path,
+            r"
+//- /lib.rs crate:dep
+pub struct Struct;
+
+//- /main.rs crate:main deps:dep
+fn main() {
+    Struct<|>
+}
+",
+            r"
+fn main() {
+    dep::Struct
+}
+",
+        );
+    }
+
+    #[test]
+    fn whole_segment() {
+        // Tests that only imports whose last segment matches the identifier get suggested.
+        check_assist(
+            qualify_path,
+            r"
+//- /lib.rs crate:dep
+pub mod fmt {
+    pub trait Display {}
+}
+
+pub fn panic_fmt() {}
+
+//- /main.rs crate:main deps:dep
+struct S;
+
+impl f<|>mt::Display for S {}
+",
+            r"
+struct S;
+
+impl dep::fmt::Display for S {}
+",
+        );
+    }
+
+    #[test]
+    fn macro_generated() {
+        // Tests that macro-generated items are suggested from external crates.
+        check_assist(
+            qualify_path,
+            r"
+//- /lib.rs crate:dep
+macro_rules! mac {
+    () => {
+        pub struct Cheese;
+    };
+}
+
+mac!();
+
+//- /main.rs crate:main deps:dep
+fn main() {
+    Cheese<|>;
+}
+",
+            r"
+fn main() {
+    dep::Cheese;
+}
+",
+        );
+    }
+
+    #[test]
+    fn casing() {
+        // Tests that differently cased names don't interfere and we only suggest the matching one.
+        check_assist(
+            qualify_path,
+            r"
+//- /lib.rs crate:dep
+pub struct FMT;
+pub struct fmt;
+
+//- /main.rs crate:main deps:dep
+fn main() {
+    FMT<|>;
+}
+",
+            r"
+fn main() {
+    dep::FMT;
+}
+",
+        );
+    }
+}