Merge pull request #30627 from LucianoPAlmeida/SR-12382-improve-pointer-conversion-mismatch-diag

[SR-12382] Improve optional pointer conversion mismatch diagnostics

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -674,6 +674,15 @@ bool GenericArgumentsMismatchFailure::diagnoseAsError() {
       }
       break;
     }
+    
+    case ConstraintLocator::OptionalPayload: {
+      // If we have an inout expression, this comes from an
+      // InoutToPointer argument mismatch failure.
+      if (isa<InOutExpr>(anchor)) {
+        diagnostic = diag::cannot_convert_argument_value;
+      }
+      break;
+    }
 
     case ConstraintLocator::TupleElement: {
       auto *anchor = getRawAnchor();

test/Constraints/valid_pointer_conversions.swift

@@ -31,6 +31,13 @@ func givesPtr(_ str: String) {
   takesDoubleOptionalPtr(i) // expected-error {{cannot convert value of type 'Int' to expected argument type 'UnsafeRawPointer??'}}
   takesMutableDoubleOptionalPtr(arr) // expected-error {{cannot convert value of type '[Int]' to expected argument type 'UnsafeMutableRawPointer??'}}
 
-  // FIXME(SR-12382): Poor diagnostic.
-  takesMutableDoubleOptionalTypedPtr(&i) // expected-error {{type of expression is ambiguous without more context}}
+  takesMutableDoubleOptionalTypedPtr(&i) // expected-error {{cannot convert value of type 'UnsafeMutablePointer<Int>' to expected argument type 'UnsafeMutablePointer<Double>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and 'Double') are expected to be equal}}
 }
+
+// SR12382
+func SR12382(_ x: UnsafeMutablePointer<Double>??) {}
+
+var i = 0
+SR12382(&i) // expected-error {{cannot convert value of type 'UnsafeMutablePointer<Int>' to expected argument type 'UnsafeMutablePointer<Double>'}}
+// expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and 'Double') are expected to be equal}}