3 files changed, 36 insertions, 9 deletions

diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 56fb7c20c..81c709bfb 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -31,6 +31,12 @@ pub trait AstToken: AstNode {
     }
 }
 
+pub trait TypeAscriptionOwner: AstNode {
+    fn ascribed_type(&self) -> Option<&TypeRef> {
+        child_opt(self)
+    }
+}
+
 pub trait NameOwner: AstNode {
     fn name(&self) -> Option<&Name> {
         child_opt(self)
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 4e2705d09..6db2f74ef 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -628,6 +628,7 @@ impl ast::NameOwner for ConstDef {}
 impl ast::TypeParamsOwner for ConstDef {}
 impl ast::AttrsOwner for ConstDef {}
 impl ast::DocCommentsOwner for ConstDef {}
+impl ast::TypeAscriptionOwner for ConstDef {}
 impl ConstDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
@@ -1767,6 +1768,7 @@ impl ToOwned for LetStmt {
 }
 
 
+impl ast::TypeAscriptionOwner for LetStmt {}
 impl LetStmt {
     pub fn pat(&self) -> Option<&Pat> {
         super::child_opt(self)
@@ -2592,6 +2594,7 @@ impl ast::VisibilityOwner for NamedFieldDef {}
 impl ast::NameOwner for NamedFieldDef {}
 impl ast::AttrsOwner for NamedFieldDef {}
 impl ast::DocCommentsOwner for NamedFieldDef {}
+impl ast::TypeAscriptionOwner for NamedFieldDef {}
 impl NamedFieldDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
@@ -2774,6 +2777,7 @@ impl ToOwned for Param {
 }
 
 
+impl ast::TypeAscriptionOwner for Param {}
 impl Param {
     pub fn pat(&self) -> Option<&Pat> {
         super::child_opt(self)
@@ -3685,6 +3689,7 @@ impl ToOwned for SelfParam {
 }
 
 
+impl ast::TypeAscriptionOwner for SelfParam {}
 impl SelfParam {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
@@ -3820,6 +3825,7 @@ impl ast::NameOwner for StaticDef {}
 impl ast::TypeParamsOwner for StaticDef {}
 impl ast::AttrsOwner for StaticDef {}
 impl ast::DocCommentsOwner for StaticDef {}
+impl ast::TypeAscriptionOwner for StaticDef {}
 impl StaticDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index c7acbbd6c..a3bfc74a7 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -271,7 +271,7 @@ Grammar(
             ]
         ),
         "NamedFieldDefList": (collections: [["fields", "NamedFieldDef"]]),
-        "NamedFieldDef": ( traits: ["VisibilityOwner", "NameOwner", "AttrsOwner", "DocCommentsOwner"], options: ["TypeRef"] ),
+        "NamedFieldDef": ( traits: ["VisibilityOwner", "NameOwner", "AttrsOwner", "DocCommentsOwner", "TypeAscriptionOwner"], options: ["TypeRef"] ),
         "PosFieldDefList": (collections: [["fields", "PosFieldDef"]]),
         "PosFieldDef": ( traits: ["VisibilityOwner", "AttrsOwner"], options: ["TypeRef"]),
         "EnumDef": ( traits: [
@@ -298,7 +298,8 @@ Grammar(
                 "NameOwner",
                 "TypeParamsOwner",
                 "AttrsOwner",
-                "DocCommentsOwner"
+                "DocCommentsOwner",
+                "TypeAscriptionOwner",
             ],
             options: ["TypeRef"]
         ),
@@ -308,7 +309,8 @@ Grammar(
                 "NameOwner",
                 "TypeParamsOwner",
                 "AttrsOwner",
-                "DocCommentsOwner"
+                "DocCommentsOwner",
+                "TypeAscriptionOwner",
             ],
             options: ["TypeRef"]
         ),
@@ -569,11 +571,16 @@ Grammar(
         "ExprStmt": (
             options: [ ["expr", "Expr"] ]
         ),
-        "LetStmt": ( options: [
-            ["pat", "Pat"],
-            ["type_ref", "TypeRef"],
-            ["initializer", "Expr"],
-        ]),
+        "LetStmt": (
+            options: [
+                ["pat", "Pat"],
+                ["type_ref", "TypeRef"],
+                ["initializer", "Expr"],
+            ],
+            traits: [
+                "TypeAscriptionOwner",
+            ]
+        ),
         "Condition": (
             options: [ "Pat", "Expr" ]
         ),
@@ -595,10 +602,18 @@ Grammar(
                 ["params", "Param"]
             ]
         ),
-        "SelfParam": (options: ["TypeRef", "SelfKw"]),
+        "SelfParam": (
+            options: ["TypeRef", "SelfKw"],
+            traits: [
+                "TypeAscriptionOwner",
+            ]
+        ),
         "SelfKw": (),
         "Param": (
             options: [ "Pat", "TypeRef" ],
+            traits: [
+                "TypeAscriptionOwner",
+            ]
         ),
         "UseItem": (
             traits: ["AttrsOwner"],