Merge pull request swiftlang#69174 from xedin/rdar-116122902

[CSDiagnostics] Adjust how requirement failures anchor type is computed

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -217,8 +217,7 @@ bool FailureDiagnostic::conformsToKnownProtocol(
 }
 
 Type RequirementFailure::getOwnerType() const {
-  auto anchor = getRawAnchor();
-
+  auto anchor = getAnchor();
   // If diagnostic is anchored at assignment expression
   // it means that requirement failure happened while trying
   // to convert source to destination, which means that

lib/Sema/ConstraintSystem.cpp

@@ -5729,6 +5729,13 @@ void constraints::simplifyLocator(ASTNode &anchor,
       // Extract tuple element.
       auto elt = path[0].castTo<LocatorPathElt::AnyTupleElement>();
       unsigned index = elt.getIndex();
+
+      if (auto *AE = getAsExpr<AssignExpr>(anchor)) {
+        if (isa<TupleExpr>(AE->getSrc())) {
+          anchor = AE->getSrc();
+        }
+      }
+
       if (auto tupleExpr = getAsExpr<TupleExpr>(anchor)) {
         if (index < tupleExpr->getNumElements()) {
           anchor = tupleExpr->getElement(index);
@@ -5744,6 +5751,7 @@ void constraints::simplifyLocator(ASTNode &anchor,
           continue;
         }
       }
+
       break;
     }
 

test/Generics/conditional_conformances.swift

@@ -355,7 +355,7 @@ func existential_good<T: P1>(_: T.Type) {
 }
 
 func existential_bad<T>(_: T.Type) {
-  _ = Free<T>() as P2 // expected-error{{protocol 'P2' requires that 'T' conform to 'P1'}}
+  _ = Free<T>() as P2 // expected-error{{generic struct 'Free' requires that 'T' conform to 'P1'}}
 }
 
 // rdar://problem/35837054

test/Generics/conditional_conformances_literals.swift

@@ -45,7 +45,7 @@ func arraySameType() {
 
     let _: SameType = arrayWorks as SameType
     let _: SameType = arrayFails as SameType
-    // expected-error@-1 {{protocol 'SameType' requires the types 'Fails' and 'Works' be equivalent}}
+    // expected-error@-1 {{generic struct 'Array' requires the types 'Fails' and 'Works' be equivalent}}
 }
 
 func dictionarySameType() {
@@ -70,7 +70,7 @@ func dictionarySameType() {
 
     let _: SameType = dictWorks as SameType
     let _: SameType = dictFails as SameType
-    // expected-error@-1 {{protocol 'SameType' requires the types 'Fails' and 'Works' be equivalent}}
+    // expected-error@-1 {{generic struct 'Dictionary' requires the types 'Fails' and 'Works' be equivalent}}
 }
 
 func arrayConforms() {
@@ -91,11 +91,11 @@ func arrayConforms() {
 
     let _: Conforms = [works] as Conforms
     let _: Conforms = [fails] as Conforms
-    // expected-error@-1 {{protocol 'Conforms' requires that 'Fails' conform to 'Conforms'}}
+    // expected-error@-1 {{generic struct 'Array' requires that 'Fails' conform to 'Conforms'}}
 
     let _: Conforms = arrayWorks as Conforms
     let _: Conforms = arrayFails as Conforms
-    // expected-error@-1 {{protocol 'Conforms' requires that 'Fails' conform to 'Conforms'}}
+    // expected-error@-1 {{generic struct 'Array' requires that 'Fails' conform to 'Conforms'}}
 }
 
 func dictionaryConforms() {
@@ -116,11 +116,11 @@ func dictionaryConforms() {
 
     let _: Conforms = [0 : works] as Conforms
     let _: Conforms = [0 : fails] as Conforms
-    // expected-error@-1 {{protocol 'Conforms' requires that 'Fails' conform to 'Conforms'}}
+    // expected-error@-1 {{generic struct 'Dictionary' requires that 'Fails' conform to 'Conforms'}}
 
     let _: Conforms = dictWorks as Conforms
     let _: Conforms = dictFails as Conforms
-    // expected-error@-1 {{protocol 'Conforms' requires that 'Fails' conform to 'Conforms'}}
+    // expected-error@-1 {{generic struct 'Dictionary' requires that 'Fails' conform to 'Conforms'}}
 }
 
 func combined() {
@@ -133,6 +133,6 @@ func combined() {
     // expected-error@-1 {{type 'any Conforms' cannot conform to 'Conforms'}} expected-note@-1 {{only concrete types such as structs, enums and classes can conform to protocols}}
 
     let _: Conforms = [[0: [1 : [fails]] as Conforms]]
-    // expected-error@-1 {{protocol 'Conforms' requires that 'Fails' conform to 'Conforms'}}
+    // expected-error@-1 {{generic struct 'Dictionary' requires that 'Fails' conform to 'Conforms'}}
     // expected-error@-2 {{type 'any Conforms' cannot conform to 'Conforms'}} expected-note@-2 {{only concrete types such as structs, enums and classes can conform to protocols}}
 }

validation-test/Sema/type_checker_crashers_fixed/rdar116122902.swift

@@ -0,0 +1,24 @@
+// RUN: %target-typecheck-verify-swift
+
+protocol AnyValue {
+}
+
+struct Value<T> {}
+
+extension Value: AnyValue where T = { // expected-error {{use '==' for same-type requirements rather than '='}} expected-error {{expected type}}
+// expected-note@-1 {{requirement from conditional conformance of 'Value<T>' to 'AnyValue'}}
+}
+
+struct Test {
+  var tuple: (value: any AnyValue, id: Int)?
+
+  mutating func test<T>(v: Value<T>) {
+    _ = {
+      // FIXME(diagnostics): We need to figure out how to avoid mentioning <<error type>> in the second diagnostic
+      self.tuple = (v, 42)
+      // expected-error@-1 {{cannot assign value of type '(Value<T>, Int)' to type '(value: any AnyValue, id: Int)'}}
+      // expected-error@-2 {{generic struct 'Value' requires the types 'T' and '<<error type>>' be equivalent}}
+      return 0
+    }
+  }
+}