Merge pull request swiftlang#83803 from hamishknight/err-fallback

Author: hamishknight

include/swift/AST/DiagnosticsSema.def

@@ -4749,15 +4749,10 @@ ERROR(could_not_infer_pack_element,none,
 NOTE(note_in_opening_pack_element,none,
       "in inferring pack element #%0 of '%1'", (unsigned,StringRef))
 
-      
-ERROR(type_of_expression_is_ambiguous,none,
-      "type of expression is ambiguous without a type annotation", ())
-
-ERROR(failed_to_produce_diagnostic,Fatal,
+ERROR(failed_to_produce_diagnostic,none,
       "failed to produce diagnostic for expression; "
       SWIFT_BUG_REPORT_MESSAGE, ())
 
-
 ERROR(missing_protocol,none,
       "missing protocol %0", (Identifier))
 ERROR(nil_literal_broken_proto,none,

lib/Sema/ConstraintSystem.cpp

@@ -4768,6 +4768,21 @@ void ConstraintSystem::diagnoseFailureFor(SyntacticElementTarget target) {
     return;
   }
 
+  if (auto *wrappedVar = target.getAsUninitializedWrappedVar()) {
+    auto *outerWrapper = wrappedVar->getOutermostAttachedPropertyWrapper();
+    Type propertyType = wrappedVar->getInterfaceType();
+    Type wrapperType = outerWrapper->getType();
+
+    // Emit the property wrapper fallback diagnostic
+    wrappedVar->diagnose(diag::property_wrapper_incompatible_property,
+                         propertyType, wrapperType);
+    if (auto nominal = wrapperType->getAnyNominal()) {
+      nominal->diagnose(diag::property_wrapper_declared_here,
+                        nominal->getName());
+    }
+    return;
+  }
+
   if (auto expr = target.getAsExpr()) {
     if (auto *assignment = dyn_cast<AssignExpr>(expr)) {
       if (isa<DiscardAssignmentExpr>(assignment->getDest()))
@@ -4785,33 +4800,12 @@ void ConstraintSystem::diagnoseFailureFor(SyntacticElementTarget target) {
         .highlight(closure->getSourceRange());
       return;
     }
-
-    // If no one could find a problem with this expression or constraint system,
-    // then it must be well-formed... but is ambiguous.  Handle this by
-    // diagnostic various cases that come up.
-    DE.diagnose(expr->getLoc(), diag::type_of_expression_is_ambiguous)
-        .highlight(expr->getSourceRange());
-  } else if (auto *wrappedVar = target.getAsUninitializedWrappedVar()) {
-    auto *outerWrapper = wrappedVar->getOutermostAttachedPropertyWrapper();
-    Type propertyType = wrappedVar->getInterfaceType();
-    Type wrapperType = outerWrapper->getType();
-
-    // Emit the property wrapper fallback diagnostic
-    wrappedVar->diagnose(diag::property_wrapper_incompatible_property,
-                         propertyType, wrapperType);
-    if (auto nominal = wrapperType->getAnyNominal()) {
-      nominal->diagnose(diag::property_wrapper_declared_here,
-                        nominal->getName());
-    }
-  } else if (target.getAsUninitializedVar()) {
-    DE.diagnose(target.getLoc(), diag::failed_to_produce_diagnostic);
-  } else if (target.isForEachPreamble()) {
-    DE.diagnose(target.getLoc(), diag::failed_to_produce_diagnostic);
-  } else {
-    // Emit a poor fallback message.
-    DE.diagnose(target.getAsFunction()->getLoc(),
-                diag::failed_to_produce_diagnostic);
   }
+
+  // Emit a poor fallback message.
+  auto diag = DE.diagnose(target.getLoc(), diag::failed_to_produce_diagnostic);
+  if (auto *expr = target.getAsExpr())
+    diag.highlight(expr->getSourceRange());
 }
 
 bool ConstraintSystem::isDeclUnavailable(const Decl *D,

test/Concurrency/sendable_keypaths.swift

@@ -224,7 +224,7 @@ do {
 
   // TODO(rdar://125948508): This shouldn't be ambiguous (@Sendable version should be preferred)
   func test() -> KeyPath<String, Int> {
-    true ? kp() : kp() // expected-error {{type of expression is ambiguous without a type annotation}}
+    true ? kp() : kp() // expected-error {{failed to produce diagnostic for expression}}
   }
 
   func forward<T>(_ v: T) -> T { v }
@@ -249,7 +249,7 @@ do {
 
   // TODO(rdar://125948508): This shouldn't be ambiguous (@Sendable version should be preferred)
   func fnRet(cond: Bool) -> () -> Void {
-    cond ? Test.fn : Test.otherFn // expected-error {{type of expression is ambiguous without a type annotation}}
+    cond ? Test.fn : Test.otherFn // expected-error {{failed to produce diagnostic for expression}}
   }
 
   func forward<T>(_: T) -> T {

test/Constraints/keypath.swift

@@ -290,7 +290,7 @@ func test_invalid_argument_to_keypath_subscript() {
   // The diagnostic should point out that `ambiguous` is indeed ambiguous and that `5` is not a valid argument
   // for a key path subscript.
   ambiguous {
-    // expected-error@-1 {{type of expression is ambiguous without a type annotation}}
+    // expected-error@-1 {{failed to produce diagnostic for expression}}
     $0[keyPath: 5]
   }
 

test/Constraints/operator.swift

@@ -285,7 +285,7 @@ func rdar60727310() {
 // FIXME: Bad diagnostic.
 func f_54877(_ e: Error) {
   func foo<T>(_ a: T, _ op: ((T, T) -> Bool)) {}
-  foo(e, ==) // expected-error {{type of expression is ambiguous without a type annotation}}
+  foo(e, ==) // expected-error {{failed to produce diagnostic for expression}}
 }
 
 // rdar://problem/62054241 - Swift compiler crashes when passing < as the sort function in sorted(by:) and the type of the array is not comparable

test/Constraints/parameterized_existentials.swift

@@ -8,7 +8,7 @@ protocol P<A> {
 
 func f1(x: any P) -> any P<Int> {
   // FIXME: Bad diagnostic
-  return x // expected-error {{type of expression is ambiguous without a type annotation}}
+  return x // expected-error {{failed to produce diagnostic for expression}}
 }
 
 func f2(x: any P<Int>) -> any P {
@@ -52,4 +52,4 @@ func h3(x: (any P<Int>)?) -> (any P<String>)? {
 
 func generic1<T>(x: any P<T>) -> T {
   return x.f()
-}
+}

test/Constraints/rdar85263844_swift6.swift

@@ -29,5 +29,5 @@ extension S4 where T == (outer: Int, y: Int) {
 
 public func rdar85263844_2(_ x: [Int]) -> S4<(outer: Int, y: Int)> {
   // FIXME: Bad error message.
-  S4(x.map { (inner: $0, y: $0) }) // expected-error {{type of expression is ambiguous without a type annotation}}
+  S4(x.map { (inner: $0, y: $0) }) // expected-error {{failed to produce diagnostic for expression}}
 }

test/Constraints/variadic_generic_constraints.swift

@@ -41,7 +41,7 @@ takesAnyObject()
 takesAnyObject(C(), C(), C())
 
 // FIXME: Bad diagnostic
-takesAnyObject(C(), S(), C())  // expected-error {{type of expression is ambiguous without a type annotation}}
+takesAnyObject(C(), S(), C())  // expected-error {{failed to produce diagnostic for expression}}
 
 // Same-type requirements
 

test/Interop/Cxx/foreign-reference/not-any-object.swift

@@ -22,5 +22,5 @@ import Test;
 public func test(_ _: AnyObject) {}
 
 // TODO: make this a better error.
-test(Empty.create()) // expected-error {{type of expression is ambiguous without a type annotation}}
+test(Empty.create()) // expected-error {{failed to produce diagnostic for expression}}
 test([Empty.create()][0]) // expected-error {{argument type 'Any' expected to be an instance of a class or class-constrained type}}

test/Interop/Cxx/namespace/import-as-member-typechecker.swift

@@ -21,4 +21,4 @@ func takesDeepNestedStruct(_ s: MyNS.MyDeepNS.DeepNestedStruct) {
 }
 
 MyNS.method() // expected-error {{type 'MyNS' has no member 'method'}}
-MyNS.nestedMethod() // expected-error {{type of expression is ambiguous without a type annotation}}
+MyNS.nestedMethod() // expected-error {{failed to produce diagnostic for expression}}