Merge pull request #73227 from cachemeifyoucan/eng/PR-testable-fallback

[ScanDependency] Allow continue searching for testable module

Author: cachemeifyoucan

include/swift/AST/DiagnosticsSema.def

@@ -1200,7 +1200,7 @@ REMARK(module_api_import_aliases,none,
        (const Decl *, ModuleDecl *, ModuleDecl *, bool))
 
 REMARK(skip_module_invalid,none,"skip invalid swiftmodule: %0", (StringRef))
-REMARK(skip_module_testable,none,"skip swiftmodule built with '-enable-testing': %0", (StringRef))
+WARNING(skip_module_not_testable,none,"ignore swiftmodule built without '-enable-testing': %0", (StringRef))
 
 REMARK(macro_loaded,none,
        "loaded macro implementation module %0 from "

lib/Serialization/SerializedModuleLoader.cpp

@@ -454,6 +454,12 @@ SerializedModuleLoaderBase::scanModuleFile(Twine modulePath, bool isFramework,
                            modulePath.str());
       return std::make_error_code(std::errc::no_such_file_or_directory);
     }
+
+    if (isTestableImport && !loadedModuleFile->isTestable()) {
+      Ctx.Diags.diagnose(SourceLoc(), diag::skip_module_not_testable,
+                         modulePath.str());
+      return std::make_error_code(std::errc::no_such_file_or_directory);
+    }
   }
 
   // Some transitive dependencies of binary modules are not required to be

test/ScanDependencies/testable-dependencies.swift

@@ -42,18 +42,21 @@
 // RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps3.json swiftPrebuiltExternal:A directDependencies | %FileCheck %s --check-prefix TEST3-A
 // TEST3-A:  "swift": "B"
 
-/// Testable import non-testable build without enable testing.
+/// Testable import sees non-testable module first, keep searching.
 // RUN: %target-swift-frontend -scan-dependencies -module-load-mode prefer-interface -module-name Test %t/testable.swift \
-// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib \
-// RUN:   -o %t/deps4.json -I %t/regular -swift-version 5
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib -enable-testing \
+// RUN:   -o %t/deps4.json -I %t/regular -I %t/testable -I %t/internal -swift-version 5 -Rmodule-loading 2>&1 | %FileCheck %s --check-prefix WARN
 // RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps4.json Test directDependencies | %FileCheck %s --check-prefix TEST4
 // TEST4:  "swiftPrebuiltExternal": "A"
-// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps4.json swiftPrebuiltExternal:A directDependencies | %FileCheck %s --check-prefix EMPTY --allow-empty
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps4.json swiftPrebuiltExternal:A directDependencies | %FileCheck %s --check-prefix TEST4-A
+// TEST4-A:  "swift": "B"
 
-/// Testable import non-testable build enable testing, still succeed since swift-frontend can provide a better diagnostics when the module is actually imported.
+/// Testable import non-testable build enable testing, warning about the finding then error out.
 // RUN: %target-swift-frontend -scan-dependencies -module-load-mode prefer-interface -module-name Test %t/testable.swift \
 // RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib -enable-testing \
-// RUN:   -o %t/deps5.json -I %t/regular -swift-version 5 -Rmodule-loading
+// RUN:   -o %t/deps5.json -I %t/regular -swift-version 5 -Rmodule-loading 2>&1 | %FileCheck %s --check-prefix WARN --check-prefix ERROR
+// WARN: warning: ignore swiftmodule built without '-enable-testing'
+// ERROR: error: Unable to find module dependency: 'A'
 
 /// Regular import a testable module with no interface, don't load optional dependencies.
 // RUN: rm %t/testable/A.swiftinterface