3 files changed, 98 insertions, 10 deletions

diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index f6e493817..9c7348898 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -512,6 +512,37 @@ fn main() { }
     }
 
     #[test]
+    fn hover_shows_fn_doc() {
+        check(
+            r#"
+/// # Example
+/// ```
+/// # use std::path::Path;
+/// #
+/// foo(Path::new("hello, world!"))
+/// ```
+pub fn foo<|>(_: &Path) {}
+
+fn main() { }
+"#,
+            expect![[r#"
+                *foo*
+                ```rust
+                pub fn foo(_: &Path)
+                ```
+                ___
+
+                # Example
+                ```
+                # use std::path::Path;
+                #
+                foo(Path::new("hello, world!"))
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
     fn hover_shows_struct_field_info() {
         // Hovering over the field when instantiating
         check(
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index ec442bcd8..6b7874460 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -4,7 +4,7 @@ mod injection;
 #[cfg(test)]
 mod tests;
 
-use hir::{Name, Semantics};
+use hir::{Name, Semantics, VariantDef};
 use ra_ide_db::{
     defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
     RootDatabase,
@@ -455,6 +455,18 @@ fn macro_call_range(macro_call: &ast::MacroCall) -> Option<TextRange> {
     Some(TextRange::new(range_start, range_end))
 }
 
+fn is_possibly_unsafe(name_ref: &ast::NameRef) -> bool {
+    name_ref
+        .syntax()
+        .parent()
+        .and_then(|parent| {
+            ast::FieldExpr::cast(parent.clone())
+                .map(|_| true)
+                .or_else(|| ast::RecordPatField::cast(parent).map(|_| true))
+        })
+        .unwrap_or(false)
+}
+
 fn highlight_element(
     sema: &Semantics<RootDatabase>,
     bindings_shadow_count: &mut FxHashMap<Name, u32>,
@@ -485,10 +497,19 @@ fn highlight_element(
             match name_kind {
                 Some(NameClass::ExternCrate(_)) => HighlightTag::Module.into(),
                 Some(NameClass::Definition(def)) => {
-                    highlight_name(db, def) | HighlightModifier::Definition
+                    highlight_name(db, def, false) | HighlightModifier::Definition
+                }
+                Some(NameClass::ConstReference(def)) => highlight_name(db, def, false),
+                Some(NameClass::FieldShorthand { field, .. }) => {
+                    let mut h = HighlightTag::Field.into();
+                    if let Definition::Field(field) = field {
+                        if let VariantDef::Union(_) = field.parent_def(db) {
+                            h |= HighlightModifier::Unsafe;
+                        }
+                    }
+
+                    h
                 }
-                Some(NameClass::ConstReference(def)) => highlight_name(db, def),
-                Some(NameClass::FieldShorthand { .. }) => HighlightTag::Field.into(),
                 None => highlight_name_by_syntax(name) | HighlightModifier::Definition,
             }
         }
@@ -499,6 +520,7 @@ fn highlight_element(
         }
         NAME_REF => {
             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
+            let possibly_unsafe = is_possibly_unsafe(&name_ref);
             match classify_name_ref(sema, &name_ref) {
                 Some(name_kind) => match name_kind {
                     NameRefClass::ExternCrate(_) => HighlightTag::Module.into(),
@@ -510,11 +532,13 @@ fn highlight_element(
                                 binding_hash = Some(calc_binding_hash(&name, *shadow_count))
                             }
                         };
-                        highlight_name(db, def)
+                        highlight_name(db, def, possibly_unsafe)
                     }
                     NameRefClass::FieldShorthand { .. } => HighlightTag::Field.into(),
                 },
-                None if syntactic_name_ref_highlighting => highlight_name_ref_by_syntax(name_ref),
+                None if syntactic_name_ref_highlighting => {
+                    highlight_name_ref_by_syntax(name_ref, sema)
+                }
                 None => HighlightTag::UnresolvedReference.into(),
             }
         }
@@ -654,10 +678,19 @@ fn is_child_of_impl(element: &SyntaxElement) -> bool {
     }
 }
 
-fn highlight_name(db: &RootDatabase, def: Definition) -> Highlight {
+fn highlight_name(db: &RootDatabase, def: Definition, possibly_unsafe: bool) -> Highlight {
     match def {
         Definition::Macro(_) => HighlightTag::Macro,
-        Definition::Field(_) => HighlightTag::Field,
+        Definition::Field(field) => {
+            let mut h = HighlightTag::Field.into();
+            if possibly_unsafe {
+                if let VariantDef::Union(_) = field.parent_def(db) {
+                    h |= HighlightModifier::Unsafe;
+                }
+            }
+
+            return h;
+        }
         Definition::ModuleDef(def) => match def {
             hir::ModuleDef::Module(_) => HighlightTag::Module,
             hir::ModuleDef::Function(func) => {
@@ -727,7 +760,7 @@ fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
     tag.into()
 }
 
-fn highlight_name_ref_by_syntax(name: ast::NameRef) -> Highlight {
+fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabase>) -> Highlight {
     let default = HighlightTag::UnresolvedReference;
 
     let parent = match name.syntax().parent() {
@@ -737,7 +770,20 @@ fn highlight_name_ref_by_syntax(name: ast::NameRef) -> Highlight {
 
     let tag = match parent.kind() {
         METHOD_CALL_EXPR => HighlightTag::Function,
-        FIELD_EXPR => HighlightTag::Field,
+        FIELD_EXPR => {
+            let h = HighlightTag::Field;
+            let is_union = ast::FieldExpr::cast(parent)
+                .and_then(|field_expr| {
+                    let field = sema.resolve_field(&field_expr)?;
+                    Some(if let VariantDef::Union(_) = field.parent_def(sema.db) {
+                        true
+                    } else {
+                        false
+                    })
+                })
+                .unwrap_or(false);
+            return if is_union { h | HighlightModifier::Unsafe } else { h.into() };
+        }
         PATH_SEGMENT => {
             let path = match parent.parent().and_then(ast::Path::cast) {
                 Some(it) => it,
diff --git a/crates/ra_ide/src/syntax_highlighting/tests.rs b/crates/ra_ide/src/syntax_highlighting/tests.rs
index b8d60bdc6..09062c38e 100644
--- a/crates/ra_ide/src/syntax_highlighting/tests.rs
+++ b/crates/ra_ide/src/syntax_highlighting/tests.rs
@@ -275,6 +275,11 @@ fn test_unsafe_highlighting() {
         r#"
 unsafe fn unsafe_fn() {}
 
+union Union {
+    a: u32,
+    b: f32,
+}
+
 struct HasUnsafeFn;
 
 impl HasUnsafeFn {
@@ -289,8 +294,14 @@ static mut global_mut: TypeForStaticMut = TypeForStaticMut { a: 0 };
 
 fn main() {
     let x = &5 as *const usize;
+    let u = Union { b: 0 };
     unsafe {
         unsafe_fn();
+        let b = u.b;
+        match u {
+            Union { b: 0 } => (),
+            Union { a } => (),
+        }
         HasUnsafeFn.unsafe_method();
         let y = *(x);
         let z = -x;