Test / Sema: Change the wording of assignment through read-only key path error

Author: sl

lib/Sema/CSDiagnostics.cpp

@@ -989,16 +989,16 @@ bool AssignmentFailure::diagnoseAsError() {
     if (!choice->isDecl()) {
       if (choice->getKind() == OverloadChoiceKind::KeyPathApplication &&
           !isa<ApplyExpr>(immInfo.first)) {
-        std::string message = "the key path";
+        std::string message = "";
         if (auto *SE = dyn_cast<SubscriptExpr>(immInfo.first)) {
           if (auto *tupleExpr = dyn_cast<TupleExpr>(SE->getIndex())) {
             if (auto *DRE = dyn_cast<DeclRefExpr>(tupleExpr->getElement(0))) {
               auto identifier = DRE->getDecl()->getBaseName().getIdentifier();
-              message = "'" + identifier.str().str() + "'";
+              message = "'" + identifier.str().str() + "' ";
             }
           }
         }
-        emitDiagnostic(Loc, DeclDiagnostic, message + " is a read-only key path")
+        emitDiagnostic(Loc, DeclDiagnostic, message + "is read-only")
             .highlight(immInfo.first->getSourceRange());
         return true;
       }
@@ -1016,7 +1016,7 @@ bool AssignmentFailure::diagnoseAsError() {
       auto type = getType(immInfo.first);
 
       if (isKnownKeyPathType(type))
-        message += " is a read-only key path";
+        message += " is read-only";
       else if (VD->isCaptureList())
         message += " is an immutable capture";
       else if (VD->isImplicit())

test/Constraints/keypath_swift_5.swift

@@ -7,15 +7,15 @@ struct S {
     let _: WritableKeyPath<S, Int> = \.i // expected-error {{cannot convert value of type 'KeyPath<S, Int>' to specified type 'WritableKeyPath<S, Int>'}}
 
     S()[keyPath: \.i] = 1
-    // expected-error@-1 {{cannot assign through subscript: the key path is a read-only key path}}
+    // expected-error@-1 {{cannot assign through subscript: is read-only}}
   }
 }
 
 func test() {
   let _: WritableKeyPath<C, Int> = \.i // expected-error {{cannot convert value of type 'KeyPath<C, Int>' to specified type 'WritableKeyPath<C, Int>'}}
 
   C()[keyPath: \.i] = 1
-  // expected-error@-1 {{cannot assign through subscript: the key path is a read-only key path}}
+  // expected-error@-1 {{cannot assign through subscript: is read-only}}
 
   let _ = C()[keyPath: \.i] // no warning for a read
 }
@@ -31,6 +31,6 @@ struct T {
 func testReadOnlyKeyPathDiagnostics() {
   let path = \T.a
   var t = T(a: 3)
-  t[keyPath: path] = 4 // expected-error {{cannot assign through subscript: 'path' is a read-only key path}}
-  t[keyPath: \T.a] = 4 // expected-error {{cannot assign through subscript: the key path is a read-only key path}}
+  t[keyPath: path] = 4 // expected-error {{cannot assign through subscript: 'path' is read-only}}
+  t[keyPath: \T.a] = 4 // expected-error {{cannot assign through subscript: is read-only}}
 }