[PR33394] Avoid lexing editor placeholders when Clang is used only

for preprocessing

r300667 added support for editor placeholder to Clang. That commit didn’t take
into account that users who use Clang for preprocessing only (-E) will get the
"editor placeholder in source file" error when preprocessing their source
(PR33394). This commit ensures that Clang doesn't lex editor placeholders when
running a preprocessor only action.

rdar://32718000

Differential Revision: https://reviews.llvm.org/D34256

llvm-svn: 305576

clang/include/clang/Lex/PreprocessorOptions.h

@@ -98,6 +98,9 @@ public:
   /// When enabled, preprocessor is in a mode for parsing a single file only.
   bool SingleFileParseMode = false;
 
+  /// When enabled, the preprocessor will construct editor placeholder tokens.
+  bool LexEditorPlaceholders = true;
+
   /// \brief True if the SourceManager should report the original file name for
   /// contents of files that were remapped to other files. Defaults to true.
   bool RemappedFilesKeepOriginalName;
@@ -185,6 +188,7 @@ public:
     ImplicitPTHInclude.clear();
     TokenCache.clear();
     SingleFileParseMode = false;
+    LexEditorPlaceholders = true;
     RetainRemappedFileBuffers = true;
     PrecompiledPreambleBytes.first = 0;
     PrecompiledPreambleBytes.second = 0;

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2379,9 +2379,51 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.AllowEditorPlaceholders = Args.hasArg(OPT_fallow_editor_placeholders);
 }
 
+static bool isStrictlyPreprocessorAction(frontend::ActionKind Action) {
+  switch (Action) {
+  case frontend::ASTDeclList:
+  case frontend::ASTDump:
+  case frontend::ASTPrint:
+  case frontend::ASTView:
+  case frontend::EmitAssembly:
+  case frontend::EmitBC:
+  case frontend::EmitHTML:
+  case frontend::EmitLLVM:
+  case frontend::EmitLLVMOnly:
+  case frontend::EmitCodeGenOnly:
+  case frontend::EmitObj:
+  case frontend::FixIt:
+  case frontend::GenerateModule:
+  case frontend::GenerateModuleInterface:
+  case frontend::GeneratePCH:
+  case frontend::GeneratePTH:
+  case frontend::ParseSyntaxOnly:
+  case frontend::ModuleFileInfo:
+  case frontend::VerifyPCH:
+  case frontend::PluginAction:
+  case frontend::PrintDeclContext:
+  case frontend::RewriteObjC:
+  case frontend::RewriteTest:
+  case frontend::RunAnalysis:
+  case frontend::MigrateSource:
+    return false;
+
+  case frontend::DumpRawTokens:
+  case frontend::DumpTokens:
+  case frontend::InitOnly:
+  case frontend::PrintPreamble:
+  case frontend::PrintPreprocessedInput:
+  case frontend::RewriteMacros:
+  case frontend::RunPreprocessorOnly:
+    return true;
+  }
+  llvm_unreachable("invalid frontend action");
+}
+
 static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
                                   FileManager &FileMgr,
-                                  DiagnosticsEngine &Diags) {
+                                  DiagnosticsEngine &Diags,
+                                  frontend::ActionKind Action) {
   using namespace options;
   Opts.ImplicitPCHInclude = Args.getLastArgValue(OPT_include_pch);
   Opts.ImplicitPTHInclude = Args.getLastArgValue(OPT_include_pth);
@@ -2454,6 +2496,12 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
     else
       Opts.ObjCXXARCStandardLibrary = (ObjCXXARCStandardLibraryKind)Library;
   }
+
+  // Always avoid lexing editor placeholders when we're just running the
+  // preprocessor as we never want to emit the
+  // "editor placeholder in source file" error in PP only mode.
+  if (isStrictlyPreprocessorAction(Action))
+    Opts.LexEditorPlaceholders = false;
 }
 
 static void ParsePreprocessorOutputArgs(PreprocessorOutputOptions &Opts,
@@ -2461,45 +2509,10 @@ static void ParsePreprocessorOutputArgs(PreprocessorOutputOptions &Opts,
                                         frontend::ActionKind Action) {
   using namespace options;
 
-  switch (Action) {
-  case frontend::ASTDeclList:
-  case frontend::ASTDump:
-  case frontend::ASTPrint:
-  case frontend::ASTView:
-  case frontend::EmitAssembly:
-  case frontend::EmitBC:
-  case frontend::EmitHTML:
-  case frontend::EmitLLVM:
-  case frontend::EmitLLVMOnly:
-  case frontend::EmitCodeGenOnly:
-  case frontend::EmitObj:
-  case frontend::FixIt:
-  case frontend::GenerateModule:
-  case frontend::GenerateModuleInterface:
-  case frontend::GeneratePCH:
-  case frontend::GeneratePTH:
-  case frontend::ParseSyntaxOnly:
-  case frontend::ModuleFileInfo:
-  case frontend::VerifyPCH:
-  case frontend::PluginAction:
-  case frontend::PrintDeclContext:
-  case frontend::RewriteObjC:
-  case frontend::RewriteTest:
-  case frontend::RunAnalysis:
-  case frontend::MigrateSource:
-    Opts.ShowCPP = 0;
-    break;
-
-  case frontend::DumpRawTokens:
-  case frontend::DumpTokens:
-  case frontend::InitOnly:
-  case frontend::PrintPreamble:
-  case frontend::PrintPreprocessedInput:
-  case frontend::RewriteMacros:
-  case frontend::RunPreprocessorOnly:
+  if (isStrictlyPreprocessorAction(Action))
     Opts.ShowCPP = !Args.hasArg(OPT_dM);
-    break;
-  }
+  else
+    Opts.ShowCPP = 0;
 
   Opts.ShowComments = Args.hasArg(OPT_C);
   Opts.ShowLineMarkers = !Args.hasArg(OPT_P);
@@ -2626,7 +2639,8 @@ bool CompilerInvocation::CreateFromArgs(CompilerInvocation &Res,
   // ParsePreprocessorArgs and remove the FileManager
   // parameters from the function and the "FileManager.h" #include.
   FileManager FileMgr(Res.getFileSystemOpts());
-  ParsePreprocessorArgs(Res.getPreprocessorOpts(), Args, FileMgr, Diags);
+  ParsePreprocessorArgs(Res.getPreprocessorOpts(), Args, FileMgr, Diags,
+                        Res.getFrontendOpts().ProgramAction);
   ParsePreprocessorOutputArgs(Res.getPreprocessorOutputOpts(), Args,
                               Res.getFrontendOpts().ProgramAction);
 

clang/lib/Lex/Lexer.cpp

@@ -19,6 +19,7 @@
 #include "clang/Lex/LexDiagnostic.h"
 #include "clang/Lex/LiteralSupport.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/Compiler.h"
@@ -2750,7 +2751,7 @@ static const char *findPlaceholderEnd(const char *CurPtr,
 
 bool Lexer::lexEditorPlaceholder(Token &Result, const char *CurPtr) {
   assert(CurPtr[-1] == '<' && CurPtr[0] == '#' && "Not a placeholder!");
-  if (!PP || LexingRawMode)
+  if (!PP || !PP->getPreprocessorOpts().LexEditorPlaceholders || LexingRawMode)
     return false;
   const char *End = findPlaceholderEnd(CurPtr + 1, BufferEnd);
   if (!End)

clang/test/Frontend/pp-only-no-editor-placeholders.c

@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -E -verify -o - %s | FileCheck %s
+// expected-no-diagnostics
+
+<#placeholder#>; // CHECK: <#placeholder#>;