Fix '-main-file-name <name>' so that it is used for the ModuleID.

[robertlytton]

Summary

Previously, you could not specify the original file name when passing a preprocessed file into the compiler
Now you can use 'clang -Xclang -main-file-name -Xclang <original file name> ...'
Or 'clang -cc1 -main-file-name <original file name> ...'

[robertlytton]

Hi Richard,
Would you be able to review, or suggest who should?
Robert

[rsmith]

LGTM with tiny fixes.

lib/CodeGen/CodeGenAction.cpp

554–557

Per coding convention, this should be named MainFileName.

test/Misc/main-file-name.c

1

This test should be in tests/CodeGen.

[robertlytton]

also 'mainFileName' should be initial capital.

lib/CodeGen/CodeGenAction.cpp

if (!LinkModuleToUse && !LinkBCFile.empty()) {
     if (error_code EC = ModuleOrErr.getError()) {
       CI.getDiagnostics().Report(diag::err_cannot_open_file)
         << LinkBCFile << EC.message();
       return 0;
     }
     LinkModuleToUse = ModuleOrErr.get();
   }
 
+  StringRef mainFileName = getCompilerInstance().getCodeGenOpts().MainFileName;
+  if (mainFileName.empty())
+    mainFileName = InFile;
   BEConsumer = new BackendConsumer(BA, CI.getDiagnostics(), CI.getCodeGenOpts(),
                                    CI.getTargetOpts(), CI.getLangOpts(),
-                                   CI.getFrontendOpts().ShowTimers, InFile,
+                                   CI.getFrontendOpts().ShowTimers, mainFileName,
                                    LinkModuleToUse, OS.release(), *VMContext);
   return BEConsumer;
 }
 
 void CodeGenAction::ExecuteAction() {
   // If this is an IR file, we have to treat it specially.
   if (getCurrentFileKind() == IK_LLVM_IR) {
     BackendAction BA = static_cast<BackendAction>(Act);

test/Misc/main-file-name.c

+// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - %s -main-file-name some.name | FileCheck -check-prefix NAMED %s
+
+// CHECK: ; ModuleID = '{{.*}}main-file-name.c'
+// NAMED: ; ModuleID = 'some.name'
+