[clang][codegen] Set CurLinkModule in CodeGenAction::ExecuteAction

CodeGenAction::ExecuteAction creates a BackendConsumer for the
purpose of handling diagnostics. The BackendConsumer's
DiagnosticHandlerImpl method expects CurLinkModule to be set,
but this did not happen on the code path that goes through
ExecuteAction. This change makes it so that the BackendConsumer
constructor used by ExecuteAction requires the Module to be
specified and passes the appropriate module in ExecuteAction.

The change also adds a test that fails without this change
and passes with it. To make the test work, the FIXME in the
handling of DK_Linker diagnostics was addressed so that warnings
and notes are no longer silently discarded. Since this introduces
a new warning diagnostic, a flag to control it (-Wlinker-warnings)
has also been added.

Reviewed By: xur

Differential Revision: https://reviews.llvm.org/D108603

1 files changed, 7 insertions, 11 deletions

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index b30bd11..e66e41d 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -160,7 +160,7 @@ namespace clang {
                     const PreprocessorOptions &PPOpts,
                     const CodeGenOptions &CodeGenOpts,
                     const TargetOptions &TargetOpts,
-                    const LangOptions &LangOpts,
+                    const LangOptions &LangOpts, llvm::Module *Module,
                     SmallVector<LinkModule, 4> LinkModules, LLVMContext &C,
                     CoverageSourceInfo *CoverageInfo = nullptr)
         : Diags(Diags), Action(Action), HeaderSearchOpts(HeaderSearchOpts),
@@ -170,7 +170,7 @@ namespace clang {
           LLVMIRGenerationRefCount(0),
           Gen(CreateLLVMCodeGen(Diags, "", HeaderSearchOpts, PPOpts,
                                 CodeGenOpts, C, CoverageInfo)),
-          LinkModules(std::move(LinkModules)) {
+          LinkModules(std::move(LinkModules)), CurLinkModule(Module) {
       TimerIsEnabled = CodeGenOpts.TimePasses;
       llvm::TimePassesIsEnabled = CodeGenOpts.TimePasses;
       llvm::TimePassesPerRun = CodeGenOpts.TimePassesPerRun;
@@ -779,11 +779,7 @@ void BackendConsumer::DiagnosticHandlerImpl(const DiagnosticInfo &DI) {
     ComputeDiagID(Severity, backend_frame_larger_than, DiagID);
     break;
   case DK_Linker:
-    assert(CurLinkModule);
-    // FIXME: stop eating the warnings and notes.
-    if (Severity != DS_Error)
-      return;
-    DiagID = diag::err_fe_cannot_link_module;
+    ComputeDiagID(Severity, linking_module, DiagID);
     break;
   case llvm::DK_OptimizationRemark:
     // Optimization remarks are always handled completely by this
@@ -845,9 +841,9 @@ void BackendConsumer::DiagnosticHandlerImpl(const DiagnosticInfo &DI) {
     DI.print(DP);
   }
 
-  if (DiagID == diag::err_fe_cannot_link_module) {
-    Diags.Report(diag::err_fe_cannot_link_module)
-        << CurLinkModule->getModuleIdentifier() << MsgStorage;
+  if (DI.getKind() == DK_Linker) {
+    assert(CurLinkModule && "CurLinkModule must be set for linker diagnostics");
+    Diags.Report(DiagID) << CurLinkModule->getModuleIdentifier() << MsgStorage;
     return;
   }
 
@@ -1088,7 +1084,7 @@ void CodeGenAction::ExecuteAction() {
   // BackendConsumer.
   BackendConsumer Result(BA, CI.getDiagnostics(), CI.getHeaderSearchOpts(),
                          CI.getPreprocessorOpts(), CI.getCodeGenOpts(),
-                         CI.getTargetOpts(), CI.getLangOpts(),
+                         CI.getTargetOpts(), CI.getLangOpts(), TheModule.get(),
                          std::move(LinkModules), *VMContext, nullptr);
   // PR44896: Force DiscardValueNames as false. DiscardValueNames cannot be
   // true here because the valued names are needed for reading textual IR.