Merge #843

843: Impl generics r=matklad a=flodiebold

This handles type parameters on impls when typing method calls.

~One remaining problem is that the autoderefs aren't applied during the unification of the method receiver type with the actual receiver type, which means that the type parameters are only correctly inferred if no autoderefs happened.~

Co-authored-by: Florian Diebold <[email protected]>

5 files changed, 141 insertions, 32 deletions

diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 8d1076774..94b757af2 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -118,11 +118,13 @@ impl Ty {
     // TODO: cache this as a query?
     // - if so, what signature? (TyFingerprint, Name)?
     // - or maybe cache all names and def_ids of methods per fingerprint?
-    pub fn lookup_method(self, db: &impl HirDatabase, name: &Name) -> Option<Function> {
-        self.iterate_methods(db, |f| {
+    /// Look up the method with the given name, returning the actual autoderefed
+    /// receiver type (but without autoref applied yet).
+    pub fn lookup_method(self, db: &impl HirDatabase, name: &Name) -> Option<(Ty, Function)> {
+        self.iterate_methods(db, |ty, f| {
             let sig = f.signature(db);
             if sig.name() == name && sig.has_self_param() {
-                Some(f)
+                Some((ty.clone(), f))
             } else {
                 None
             }
@@ -134,7 +136,7 @@ impl Ty {
     pub fn iterate_methods<T>(
         self,
         db: &impl HirDatabase,
-        mut callback: impl FnMut(Function) -> Option<T>,
+        mut callback: impl FnMut(&Ty, Function) -> Option<T>,
     ) -> Option<T> {
         // For method calls, rust first does any number of autoderef, and then one
         // autoref (i.e. when the method takes &self or &mut self). We just ignore
@@ -156,7 +158,7 @@ impl Ty {
                 for item in impl_block.items(db) {
                     match item {
                         ImplItem::Method(f) => {
-                            if let Some(result) = callback(f) {
+                            if let Some(result) = callback(&derefed_ty, f) {
                                 return Some(result);
                             }
                         }
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_generic_chain.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_generic_chain.snap
index 626f31252..d1ce87b0a 100644
--- a/crates/ra_hir/src/ty/snapshots/tests__infer_generic_chain.snap
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_generic_chain.snap
@@ -1,36 +1,36 @@
 ---
-created: "2019-01-27T14:52:29.938713255+00:00"
-creator: [email protected]
-expression: "&result"
+created: "2019-02-16T20:53:59.655361804Z"
+creator: [email protected]
 source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
 ---
-[53; 57) 'self': A<[unknown]>
-[65; 87) '{     ...     }': [unknown]
-[75; 79) 'self': A<[unknown]>
-[75; 81) 'self.x': [unknown]
+[53; 57) 'self': A<T2>
+[65; 87) '{     ...     }': T2
+[75; 79) 'self': A<T2>
+[75; 81) 'self.x': T2
 [99; 100) 't': T
 [110; 115) '{ t }': T
 [112; 113) 't': T
 [135; 261) '{     ....x() }': i128
-[146; 147) 'x': i32
-[150; 151) '1': i32
-[162; 163) 'y': i32
-[166; 168) 'id': fn id<i32>(T) -> T
-[166; 171) 'id(x)': i32
-[169; 170) 'x': i32
-[182; 183) 'a': A<i32>
-[186; 200) 'A { x: id(y) }': A<i32>
-[193; 195) 'id': fn id<i32>(T) -> T
-[193; 198) 'id(y)': i32
-[196; 197) 'y': i32
-[211; 212) 'z': i32
-[215; 217) 'id': fn id<i32>(T) -> T
-[215; 222) 'id(a.x)': i32
-[218; 219) 'a': A<i32>
-[218; 221) 'a.x': i32
-[233; 234) 'b': A<i32>
-[237; 247) 'A { x: z }': A<i32>
-[244; 245) 'z': i32
-[254; 255) 'b': A<i32>
+[146; 147) 'x': i128
+[150; 151) '1': i128
+[162; 163) 'y': i128
+[166; 168) 'id': fn id<i128>(T) -> T
+[166; 171) 'id(x)': i128
+[169; 170) 'x': i128
+[182; 183) 'a': A<i128>
+[186; 200) 'A { x: id(y) }': A<i128>
+[193; 195) 'id': fn id<i128>(T) -> T
+[193; 198) 'id(y)': i128
+[196; 197) 'y': i128
+[211; 212) 'z': i128
+[215; 217) 'id': fn id<i128>(T) -> T
+[215; 222) 'id(a.x)': i128
+[218; 219) 'a': A<i128>
+[218; 221) 'a.x': i128
+[233; 234) 'b': A<i128>
+[237; 247) 'A { x: z }': A<i128>
+[244; 245) 'z': i128
+[254; 255) 'b': A<i128>
 [254; 259) 'b.x()': i128
 
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics.snap
new file mode 100644
index 000000000..44f00a52e
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics.snap
@@ -0,0 +1,39 @@
+---
+created: "2019-02-16T21:58:14.029368845Z"
+creator: [email protected]
+source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
+---
+[74; 78) 'self': A<X, Y>
+[85; 107) '{     ...     }': X
+[95; 99) 'self': A<X, Y>
+[95; 101) 'self.x': X
+[117; 121) 'self': A<X, Y>
+[128; 150) '{     ...     }': Y
+[138; 142) 'self': A<X, Y>
+[138; 144) 'self.y': Y
+[163; 167) 'self': A<X, Y>
+[169; 170) 't': T
+[188; 223) '{     ...     }': (X, Y, T)
+[198; 217) '(self.....y, t)': (X, Y, T)
+[199; 203) 'self': A<X, Y>
+[199; 205) 'self.x': X
+[207; 211) 'self': A<X, Y>
+[207; 213) 'self.y': Y
+[215; 216) 't': T
+[245; 342) '{     ...(1); }': ()
+[255; 256) 'a': A<u64, i64>
+[259; 281) 'A { x:...1i64 }': A<u64, i64>
+[266; 270) '1u64': u64
+[275; 279) '1i64': i64
+[287; 288) 'a': A<u64, i64>
+[287; 292) 'a.x()': u64
+[298; 299) 'a': A<u64, i64>
+[298; 303) 'a.y()': i64
+[309; 310) 'a': A<u64, i64>
+[309; 319) 'a.z(1i128)': (u64, i64, i128)
+[313; 318) '1i128': i128
+[325; 326) 'a': A<u64, i64>
+[325; 339) 'a.z::<u128>(1)': (u64, i64, u128)
+[337; 338) '1': u128
+
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics_with_autoderef.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics_with_autoderef.snap
new file mode 100644
index 000000000..f609eaf7c
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_impl_generics_with_autoderef.snap
@@ -0,0 +1,16 @@
+---
+created: "2019-02-17T13:35:06.385679926Z"
+creator: [email protected]
+source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
+---
+[78; 82) 'self': &Option<T>
+[98; 100) '{}': ()
+[111; 112) 'o': Option<u32>
+[127; 165) '{     ...f(); }': ()
+[133; 146) '(&o).as_ref()': Option<&u32>
+[134; 136) '&o': &Option<u32>
+[135; 136) 'o': Option<u32>
+[152; 153) 'o': Option<u32>
+[152; 162) 'o.as_ref()': Option<&u32>
+
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 203f1fe4d..5eb9c4f5b 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -507,6 +507,58 @@ fn test() {
 }
 
 #[test]
+fn infer_impl_generics() {
+    check_inference(
+        "infer_impl_generics",
+        r#"
+struct A<T1, T2> {
+    x: T1,
+    y: T2,
+}
+impl<Y, X> A<X, Y> {
+    fn x(self) -> X {
+        self.x
+    }
+    fn y(self) -> Y {
+        self.y
+    }
+    fn z<T>(self, t: T) -> (X, Y, T) {
+        (self.x, self.y, t)
+    }
+}
+
+fn test() -> i128 {
+    let a = A { x: 1u64, y: 1i64 };
+    a.x();
+    a.y();
+    a.z(1i128);
+    a.z::<u128>(1);
+}
+"#,
+    );
+}
+
+#[test]
+fn infer_impl_generics_with_autoderef() {
+    check_inference(
+        "infer_impl_generics_with_autoderef",
+        r#"
+enum Option<T> {
+    Some(T),
+    None,
+}
+impl<T> Option<T> {
+    fn as_ref(&self) -> Option<&T> {}
+}
+fn test(o: Option<u32>) {
+    (&o).as_ref();
+    o.as_ref();
+}
+"#,
+    );
+}
+
+#[test]
 fn infer_generic_chain() {
     check_inference(
         "infer_generic_chain",