[clang][modules] Cherry-picks for minor fixes

clang/include/clang/Basic/DiagnosticSerializationKinds.td

@@ -24,8 +24,9 @@ def err_fe_ast_file_modified : Error<
     DefaultFatal;
 def err_fe_pch_file_overridden : Error<
     "file '%0' from the precompiled header has been overridden">;
-def note_pch_required_by : Note<"'%0' required by '%1'">;
-def note_pch_rebuild_required : Note<"please rebuild precompiled header '%0'">;
+def note_ast_file_required_by : Note<"'%0' required by '%1'">;
+def note_ast_file_rebuild_required
+    : Note<"please rebuild precompiled file '%0'">;
 def note_module_cache_path : Note<
     "after modifying system headers, please delete the module cache at '%0'">;
 

clang/lib/Lex/DependencyDirectivesScanner.cpp

@@ -496,7 +496,15 @@ bool Scanner::lexModuleDirectiveBody(DirectiveKind Kind, const char *&First,
                                      const char *const End) {
   const char *DirectiveLoc = Input.data() + CurDirToks.front().Offset;
   for (;;) {
+    // Keep a copy of the First char incase it needs to be reset.
+    const char *Previous = First;
     const dependency_directives_scan::Token &Tok = lexToken(First, End);
+    if ((Tok.is(tok::hash) || Tok.is(tok::at)) &&
+        (Tok.Flags & clang::Token::StartOfLine)) {
+      CurDirToks.pop_back();
+      First = Previous;
+      return false;
+    }
     if (Tok.is(tok::eof))
       return reportError(
           DirectiveLoc,
@@ -846,6 +854,7 @@ bool Scanner::lexPPLine(const char *&First, const char *const End) {
   if (*First == '@')
     return lexAt(First, End);
 
+  // Handle module directives for C++20 modules.
   if (*First == 'i' || *First == 'e' || *First == 'm')
     return lexModule(First, End);
 

clang/lib/Serialization/ASTReader.cpp

@@ -2680,25 +2680,25 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
       while (!ImportStack.back()->ImportedBy.empty())
         ImportStack.push_back(ImportStack.back()->ImportedBy[0]);
 
-      // The top-level PCH is stale.
-      StringRef TopLevelPCHName(ImportStack.back()->FileName);
+      // The top-level AST file is stale.
+      StringRef TopLevelASTFileName(ImportStack.back()->FileName);
       Diag(diag::err_fe_ast_file_modified)
           << *Filename << moduleKindForDiagnostic(ImportStack.back()->Kind)
-          << TopLevelPCHName << FileChange.Kind
+          << TopLevelASTFileName << FileChange.Kind
           << (FileChange.Old && FileChange.New)
           << llvm::itostr(FileChange.Old.value_or(0))
           << llvm::itostr(FileChange.New.value_or(0));
 
       // Print the import stack.
       if (ImportStack.size() > 1) {
-        Diag(diag::note_pch_required_by)
+        Diag(diag::note_ast_file_required_by)
             << *Filename << ImportStack[0]->FileName;
         for (unsigned I = 1; I < ImportStack.size(); ++I)
-          Diag(diag::note_pch_required_by)
-            << ImportStack[I-1]->FileName << ImportStack[I]->FileName;
+          Diag(diag::note_ast_file_required_by)
+              << ImportStack[I - 1]->FileName << ImportStack[I]->FileName;
       }
 
-      Diag(diag::note_pch_rebuild_required) << TopLevelPCHName;
+      Diag(diag::note_ast_file_rebuild_required) << TopLevelASTFileName;
     }
 
     IsOutOfDate = true;

clang/test/Modules/module-file-modified.c

@@ -8,4 +8,5 @@
 #include "a.h"
 int foo = 0; // redefinition of 'foo'
 // CHECK: fatal error: file {{.*}} has been modified since the module file {{.*}} was built
+// CHECK: note: please rebuild precompiled file
 // REQUIRES: shell

clang/test/Modules/validate-file-content.m

@@ -29,5 +29,5 @@
 // CHECK: file '[[M_H:.*[/\\]m\.h]]' has been modified since the precompiled header '[[A_PCH:.*/a\.pch]]' was built: content changed
 // CHECK: '[[M_H]]' required by '[[M_PCM:.*[/\\]m.*\.pcm]]'
 // CHECK: '[[M_PCM]]' required by '[[A_PCH]]'
-// CHECK: please rebuild precompiled header '[[A_PCH]]'
+// CHECK: please rebuild precompiled file '[[A_PCH]]'
 // expected-no-diagnostics

clang/test/PCH/modified-module-dependency.m

@@ -17,4 +17,4 @@
 // CHECK: file '[[TEST_H:.*[/\\]test\.h]]' has been modified since the precompiled header '[[PREFIX_PCH:.*/prefix\.pch]]' was built
 // CHECK: '[[TEST_H]]' required by '[[TEST_PCM:.*[/\\]test\.pcm]]'
 // CHECK: '[[TEST_PCM]]' required by '[[PREFIX_PCH]]'
-// CHECK: please rebuild precompiled header '[[PREFIX_PCH]]'
+// CHECK: please rebuild precompiled file '[[PREFIX_PCH]]'

clang/test/PCH/validate-file-content.m

@@ -25,5 +25,5 @@
 // RUN: FileCheck %s < %t/stderr
 //
 // CHECK: file '[[M_H:.*[/\\]m\.h]]' has been modified since the precompiled header '[[A_PCH:.*/a\.pch]]' was built: content changed
-// CHECK: please rebuild precompiled header '[[A_PCH]]'
+// CHECK: please rebuild precompiled file '[[A_PCH]]'
 // expected-no-diagnostics

clang/unittests/Lex/DependencyDirectivesScannerTest.cpp

@@ -661,13 +661,28 @@ TEST(MinimizeSourceToDependencyDirectivesTest, EmptyIncludesAndImports) {
                                                    Out));
 }
 
-TEST(MinimizeSourceToDependencyDirectivesTest, AtImportFailures) {
+TEST(MinimizeSourceToDependencyDirectivesTest, ImportFailures) {
   SmallVector<char, 128> Out;
 
   ASSERT_TRUE(minimizeSourceToDependencyDirectives("@import A\n", Out));
   ASSERT_FALSE(
       minimizeSourceToDependencyDirectives("@import MACRO(A);\n", Out));
   ASSERT_FALSE(minimizeSourceToDependencyDirectives("@import \" \";\n", Out));
+
+  ASSERT_FALSE(minimizeSourceToDependencyDirectives("import <Foo.h>\n"
+                                                    "@import Foo;",
+                                                    Out));
+  EXPECT_STREQ("@import Foo;\n", Out.data());
+
+  ASSERT_FALSE(
+      minimizeSourceToDependencyDirectives("import <Foo.h>\n"
+                                           "#import <Foo.h>\n"
+                                           "@;\n"
+                                           "#pragma clang module import Foo",
+                                           Out));
+  EXPECT_STREQ("#import <Foo.h>\n"
+               "#pragma clang module import Foo\n",
+               Out.data());
 }
 
 TEST(MinimizeSourceToDependencyDirectivesTest, RawStringLiteral) {