[Dependency Scanning] Emit a warning when failing to load a binary module of a non-resilient dependency

include/swift/AST/DiagnosticsSema.def

@@ -1230,8 +1230,14 @@ REMARK(module_api_import_aliases,none,
        "%select{, which reexports definition from %2|}3",
        (const Decl *, ModuleDecl *, ModuleDecl *, bool))
 
-REMARK(skip_module_invalid,none,"skip invalid swiftmodule: %0", (StringRef))
-WARNING(skip_module_not_testable,none,"ignore swiftmodule built without '-enable-testing': %0", (StringRef))
+REMARK(dependency_scan_skip_module_invalid,none,
+       "module file '%0' skipped by the dependency scan because it is "
+       "incompatible with this Swift compiler: %1", (StringRef, StringRef))
+WARNING(skip_module_not_testable,none,
+        "ignore swiftmodule built without '-enable-testing': %0", (StringRef))
+WARNING(dependency_scan_module_incompatible, none,
+        "module file '%0' is incompatible with this Swift compiler: %1",
+        (StringRef, StringRef))
 
 REMARK(macro_loaded,none,
        "loaded macro implementation module %0 from "

include/swift/Serialization/SerializedModuleLoader.h

@@ -18,6 +18,7 @@
 #include "swift/AST/ModuleDependencies.h"
 #include "swift/AST/ModuleLoader.h"
 #include "swift/AST/SearchPathOptions.h"
+#include "swift/Serialization/Validation.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PrefixMapper.h"
 #include "llvm/TargetParser/Triple.h"
@@ -165,7 +166,8 @@ class SerializedModuleLoaderBase : public ModuleLoader {
 
   /// Scan the given serialized module file to determine dependencies.
   llvm::ErrorOr<ModuleDependencyInfo>
-  scanModuleFile(Twine modulePath, bool isFramework, bool isTestableImport);
+  scanModuleFile(Twine modulePath, bool isFramework,
+                 bool isTestableImport, bool isCandidateForTextualModule);
 
   struct BinaryModuleImports {
     llvm::StringSet<> moduleImports;
@@ -267,6 +269,10 @@ class SerializedModuleLoaderBase : public ModuleLoader {
                         InterfaceSubContextDelegate &delegate,
                         llvm::PrefixMapper *mapper,
                         bool isTestableImport) override;
+
+  /// A textual reason why the compiler rejected a binary module load
+  /// attempt with a given status, to be used for diagnostic output.
+  static std::optional<std::string> invalidModuleReason(serialization::Status status);
 };
 
 /// Imports serialized Swift modules into an ASTContext.

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -325,45 +325,6 @@ struct ModuleRebuildInfo {
     return false;
   }
 
-  const char *invalidModuleReason(serialization::Status status) {
-    using namespace serialization;
-    switch (status) {
-    case Status::FormatTooOld:
-      return "compiled with an older version of the compiler";
-    case Status::FormatTooNew:
-      return "compiled with a newer version of the compiler";
-    case Status::RevisionIncompatible:
-      return "compiled with a different version of the compiler";
-    case Status::ChannelIncompatible:
-      return "compiled for a different distribution channel";
-    case Status::NotInOSSA:
-      return "module was not built with OSSA";
-    case Status::MissingDependency:
-      return "missing dependency";
-    case Status::MissingUnderlyingModule:
-      return "missing underlying module";
-    case Status::CircularDependency:
-      return "circular dependency";
-    case Status::FailedToLoadBridgingHeader:
-      return "failed to load bridging header";
-    case Status::Malformed:
-      return "malformed";
-    case Status::MalformedDocumentation:
-      return "malformed documentation";
-    case Status::NameMismatch:
-      return "name mismatch";
-    case Status::TargetIncompatible:
-      return "compiled for a different target platform";
-    case Status::TargetTooNew:
-      return "target platform newer than current platform";
-    case Status::SDKMismatch:
-      return "SDK does not match";
-    case Status::Valid:
-      return nullptr;
-    }
-    llvm_unreachable("bad status");
-  }
-
   /// Emits a diagnostic for all out-of-date compiled or forwarding modules
   /// encountered while trying to load a module.
   template<typename... DiagArgs>
@@ -406,9 +367,9 @@ struct ModuleRebuildInfo {
       // If there was a compiled module that wasn't able to be read, diagnose
       // the reason we couldn't read it.
       if (auto status = mod.serializationStatus) {
-        if (auto reason = invalidModuleReason(*status)) {
+        if (auto reason = SerializedModuleLoaderBase::invalidModuleReason(*status)) {
           diags.diagnose(loc, diag::compiled_module_invalid_reason,
-              mod.path, reason);
+                         mod.path, reason.value());
         } else {
           diags.diagnose(loc, diag::compiled_module_invalid, mod.path);
         }

lib/Serialization/ScanningLoaders.cpp

@@ -61,7 +61,9 @@ std::error_code SwiftModuleScanner::findModuleFilesInDirectory(
     if (fs.exists(ModPath)) {
       // The module file will be loaded directly.
       auto dependencies =
-          scanModuleFile(ModPath, IsFramework, isTestableDependencyLookup);
+          scanModuleFile(ModPath, IsFramework,
+                         isTestableDependencyLookup,
+                         /* isCandidateForTextualModule */ false);
       if (dependencies) {
         this->dependencies = std::move(dependencies.get());
         return std::error_code();
@@ -164,8 +166,9 @@ SwiftModuleScanner::scanInterfaceFile(Twine moduleInterfacePath,
             Ctx.SearchPathOpts.ScannerModuleValidation) {
           assert(compiledCandidates.size() == 1 &&
                  "Should only have 1 candidate module");
-          auto BinaryDep = scanModuleFile(compiledCandidates[0], isFramework,
-                                          isTestableImport);
+          auto BinaryDep = scanModuleFile(compiledCandidates[0],
+                                          isFramework, isTestableImport,
+                                          /* isCandidateForTextualModule */ true);
           if (BinaryDep) {
             Result = *BinaryDep;
             return std::error_code();

lib/Serialization/SerializedModuleLoader.cpp

@@ -304,6 +304,45 @@ SerializedModuleLoaderBase::getModuleName(ASTContext &Ctx, StringRef modulePath,
   return ModuleFile::getModuleName(Ctx, modulePath, Name);
 }
 
+std::optional<std::string> SerializedModuleLoaderBase::invalidModuleReason(serialization::Status status) {
+  using namespace serialization;
+  switch (status) {
+  case Status::FormatTooOld:
+    return "compiled with an older version of the compiler";
+  case Status::FormatTooNew:
+    return "compiled with a newer version of the compiler";
+  case Status::RevisionIncompatible:
+    return "compiled with a different version of the compiler";
+  case Status::ChannelIncompatible:
+    return "compiled for a different distribution channel";
+  case Status::NotInOSSA:
+    return "module was not built with OSSA";
+  case Status::MissingDependency:
+    return "missing dependency";
+  case Status::MissingUnderlyingModule:
+    return "missing underlying module";
+  case Status::CircularDependency:
+    return "circular dependency";
+  case Status::FailedToLoadBridgingHeader:
+    return "failed to load bridging header";
+  case Status::Malformed:
+    return "malformed";
+  case Status::MalformedDocumentation:
+    return "malformed documentation";
+  case Status::NameMismatch:
+    return "name mismatch";
+  case Status::TargetIncompatible:
+    return "compiled for a different target platform";
+  case Status::TargetTooNew:
+    return "target platform newer than current platform";
+  case Status::SDKMismatch:
+    return "SDK does not match";
+  case Status::Valid:
+    return std::nullopt;
+  }
+  llvm_unreachable("bad status");
+}
+
 llvm::ErrorOr<llvm::StringSet<>>
 SerializedModuleLoaderBase::getMatchingPackageOnlyImportsOfModule(
     Twine modulePath, bool isFramework, bool isRequiredOSSAModules,
@@ -504,7 +543,8 @@ SerializedModuleLoaderBase::resolveMacroPlugin(const ExternalMacroPlugin &macro,
 
 llvm::ErrorOr<ModuleDependencyInfo>
 SerializedModuleLoaderBase::scanModuleFile(Twine modulePath, bool isFramework,
-                                           bool isTestableImport) {
+                                           bool isTestableImport,
+                                           bool isCandidateForTextualModule) {
   const std::string moduleDocPath;
   const std::string sourceInfoPath;
 
@@ -521,10 +561,19 @@ SerializedModuleLoaderBase::scanModuleFile(Twine modulePath, bool isFramework,
 
   if (Ctx.SearchPathOpts.ScannerModuleValidation) {
     // If failed to load, just ignore and return do not found.
-    if (loadInfo.status != serialization::Status::Valid) {
+    if (auto loadFailureReason = invalidModuleReason(loadInfo.status)) {
+      // If no textual interface was found, then for this dependency
+      // scanning query this was *the* module discovered, which means
+      // it would be helpful to let the user know why the scanner
+      // was not able to use it because the scan will ultimately fail to
+      // resolve this dependency due to this incompatibility.
+      if (!isCandidateForTextualModule)
+        Ctx.Diags.diagnose(SourceLoc(), diag::dependency_scan_module_incompatible,
+                           modulePath.str(), loadFailureReason.value());
+
       if (Ctx.LangOpts.EnableModuleLoadingRemarks)
-        Ctx.Diags.diagnose(SourceLoc(), diag::skip_module_invalid,
-                           modulePath.str());
+        Ctx.Diags.diagnose(SourceLoc(), diag::dependency_scan_skip_module_invalid,
+                           modulePath.str(), loadFailureReason.value());
       return std::make_error_code(std::errc::no_such_file_or_directory);
     }
 

test/ScanDependencies/invalid_binary_module_only.swift

@@ -0,0 +1,13 @@
+// RUN: %empty-directory(%t)
+// RUN: mkdir -p %t/clang-module-cache
+// RUN: mkdir -p %t/moduleInputs
+
+// RUN: echo "Not Really a module" >> %t/moduleInputs/FooBar.swiftmodule
+
+// RUN: %target-swift-frontend -scan-dependencies -module-cache-path %t/clang-module-cache %s -o %t/deps.json -I %t/moduleInputs -diagnostic-style llvm -scanner-module-validation 2>&1 | %FileCheck %s
+
+import FooBar
+
+// CHECK: warning: module file '{{.*}}{{/|\\}}moduleInputs{{/|\\}}FooBar.swiftmodule' is incompatible with this Swift compiler: malformed
+// CHECK: error: Unable to find module dependency: 'FooBar'
+