Merge pull request #70424 from xymus/ambiguity

AST: Specify the module name in errors on ambiguities across modules

Author: xymus

include/swift/AST/DiagnosticsSema.def

@@ -4271,6 +4271,9 @@ WARNING(warn_use_async_alternative,none,
 
 NOTE(found_candidate,none,
      "found this candidate", ())
+NOTE(found_candidate_in_module,none,
+     "found this candidate %select{|in module %1}0",
+     (bool, const ModuleDecl *))
 NOTE(found_candidate_type,none,
      "found candidate with type %0", (Type))
 

lib/Sema/ConstraintSystem.cpp

@@ -5663,12 +5663,17 @@ bool ConstraintSystem::diagnoseAmbiguity(ArrayRef<Solution> solutions) {
       case OverloadChoiceKind::Decl:
       case OverloadChoiceKind::DeclViaDynamic:
       case OverloadChoiceKind::DeclViaBridge:
-      case OverloadChoiceKind::DeclViaUnwrappedOptional:
+      case OverloadChoiceKind::DeclViaUnwrappedOptional: {
         // FIXME: show deduced types, etc, etc.
-        if (EmittedDecls.insert(choice.getDecl()).second)
-          DE.diagnose(choice.getDecl(), diag::found_candidate);
+        auto decl = choice.getDecl();
+        if (EmittedDecls.insert(decl).second) {
+          auto declModule = decl->getDeclContext()->getParentModule();
+          bool printModuleName = declModule != DC->getParentModule();
+          DE.diagnose(decl, diag::found_candidate_in_module,
+                      printModuleName, declModule);
+        }
         break;
-
+      }
       case OverloadChoiceKind::KeyPathApplication:
       case OverloadChoiceKind::DynamicMemberLookup:
       case OverloadChoiceKind::KeyPathDynamicMemberLookup:

test/diagnostics/ambiguity-across-modules.swift

@@ -0,0 +1,58 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+/// Compile the exact same source file into 2 different modules.
+// RUN: %target-swift-frontend -emit-module -o %t/A.swiftmodule %t/Lib.swift \
+// RUN:    -emit-module-source-info -module-name A -package-name pkg \
+// RUN:    -enable-testing
+// RUN: %target-swift-frontend -emit-module -o %t/B.swiftmodule %t/Lib.swift \
+// RUN:    -emit-module-source-info -module-name B -package-name pkg \
+// RUN:    -enable-testing
+
+// Build a client importing both modules and hitting the ambiguities.
+// RUN: not %target-swift-frontend -typecheck -I %t %t/Client.swift -package-name pkg 2> %t/out
+// RUN: cat %t/out | %FileCheck %s
+
+//--- Lib.swift
+public func publicAmbiguity() {}
+package func packageAmbiguity() {}
+internal func internalAmbiguity() {}
+
+//--- Client.swift
+@testable import A
+@testable import B
+
+func foo() {
+  publicAmbiguity()
+// CHECK: error: ambiguous use of 'publicAmbiguity()'
+// CHECK-NEXT:  publicAmbiguity()
+// CHECK-NEXT:  ^
+// CHECK-NEXT: Lib.swift:1:13: note: found this candidate in module 'A'
+// CHECK-NEXT: public func publicAmbiguity() {}
+// CHECK-NEXT:             ^
+// CHECK-NEXT: Lib.swift:1:13: note: found this candidate in module 'B'
+// CHECK-NEXT: public func publicAmbiguity() {}
+// CHECK-NEXT:             ^
+
+  packageAmbiguity()
+// CHECK: error: ambiguous use of 'packageAmbiguity()'
+// CHECK-NEXT:  packageAmbiguity()
+// CHECK-NEXT:  ^
+// CHECK-NEXT: Lib.swift:2:14: note: found this candidate in module 'A'
+// CHECK-NEXT: package func packageAmbiguity() {}
+// CHECK-NEXT:             ^
+// CHECK-NEXT: Lib.swift:2:14: note: found this candidate in module 'B'
+// CHECK-NEXT: package func packageAmbiguity() {}
+// CHECK-NEXT:             ^
+
+  internalAmbiguity()
+// CHECK: error: ambiguous use of 'internalAmbiguity()'
+// CHECK-NEXT:  internalAmbiguity()
+// CHECK-NEXT:  ^
+// CHECK-NEXT: Lib.swift:3:15: note: found this candidate in module 'A'
+// CHECK-NEXT: internal func internalAmbiguity() {}
+// CHECK-NEXT:             ^
+// CHECK-NEXT: Lib.swift:3:15: note: found this candidate in module 'B'
+// CHECK-NEXT: internal func internalAmbiguity() {}
+// CHECK-NEXT:             ^
+}

test/diagnostics/testable-printast-locations.swift

@@ -9,5 +9,5 @@
 ambiguous()
 
 // CHECK: testable-printast-locations.swift:[[@LINE-2]]:1: error: ambiguous use of 'ambiguous()'
-// CHECK: ModuleA.ambiguous (internal):1:15: note: found this candidate
-// CHECK: ModuleB.ambiguous (internal):1:15: note: found this candidate
+// CHECK: ModuleA.ambiguous (internal):1:15: note: found this candidate in module 'ModuleA'
+// CHECK: ModuleB.ambiguous (internal):1:15: note: found this candidate in module 'ModuleB'