[Sema] Note which import restricts conformances and typealiases in API

Author: xymus

include/swift/AST/DiagnosticsSema.def

@@ -2337,7 +2337,7 @@ NOTE(decl_import_via_here,none,
      "%kind0 imported as "
      "'%select{private|fileprivate|internal|package|%ERROR|%ERROR}1' "
      "from %2 here",
-     (const ValueDecl *, AccessLevel, const ModuleDecl*))
+     (const Decl *, AccessLevel, const ModuleDecl*))
 
 // Opaque return types
 ERROR(opaque_type_invalid_constraint,none,

lib/Sema/ResilienceDiagnostics.cpp

@@ -177,6 +177,19 @@ static bool diagnoseTypeAliasDeclRefExportability(SourceLoc loc,
       !ctx.LangOpts.isSwiftVersionAtLeast(6))
     addMissingImport(loc, D, where);
 
+  // If limited by an import, note which one.
+  if (originKind == DisallowedOriginKind::NonPublicImport) {
+    const DeclContext *DC = where.getDeclContext();
+    ImportAccessLevel limitImport = D->getImportAccessFrom(DC);
+    assert(limitImport.has_value() &&
+           limitImport->accessLevel < AccessLevel::Public &&
+           "The import should still be non-public");
+    ctx.Diags.diagnose(limitImport->accessLevelLoc,
+                       diag::decl_import_via_here, D,
+                       limitImport->accessLevel,
+                       limitImport->module.importedModule);
+  }
+
   return true;
 }
 
@@ -303,5 +316,18 @@ TypeChecker::diagnoseConformanceExportability(SourceLoc loc,
       !ctx.LangOpts.isSwiftVersionAtLeast(6))
     addMissingImport(loc, ext, where);
 
+  // If limited by an import, note which one.
+  if (originKind == DisallowedOriginKind::NonPublicImport) {
+    const DeclContext *DC = where.getDeclContext();
+    ImportAccessLevel limitImport = ext->getImportAccessFrom(DC);
+    assert(limitImport.has_value() &&
+           limitImport->accessLevel < AccessLevel::Public &&
+           "The import should still be non-public");
+    ctx.Diags.diagnose(limitImport->accessLevelLoc,
+                       diag::decl_import_via_here, ext,
+                       limitImport->accessLevel,
+                       limitImport->module.importedModule);
+  }
+
   return true;
 }

test/Sema/access-level-import-conformances.swift

@@ -21,7 +21,7 @@ extension ConformingType : Proto  {}
 
 //--- Client.swift
 public import ConformanceBaseTypes
-internal import ConformanceDefinition
+internal import ConformanceDefinition // expected-note 2 {{extension of struct 'ConformingType' imported as 'internal' from 'ConformanceDefinition' here}}
 
 public func useInAPI(a: any Proto = ConformingType()) { // expected-error {{cannot use conformance of 'ConformingType' to 'Proto' here; 'ConformanceDefinition' was not imported publicly}}
 }

test/Sema/access-level-import-typealias.swift

@@ -20,7 +20,7 @@ public typealias ClazzAlias = Clazz
 
 //--- UsesAliasesNoImport.swift
 public import Aliases
-internal import Original
+internal import Original // expected-note 2 {{class 'Clazz' imported as 'internal' from 'Original' here}}
 
 // expected-error@+1 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used here because 'Original' was not imported publicly}}
 public class InheritsFromClazzAlias: ClazzAlias {}