[SYCL] Improve kernel name diagnostic

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -12197,7 +12197,7 @@ def err_sycl_entry_point_on_main : Error<
 def err_sycl_kernel_name_type : Error<
   "'sycl_kernel_entry_point' kernel name argument must be a class type">;
 def err_sycl_kernel_name_conflict : Error<
-  "'sycl_kernel_entry_point' kernel name argument conflicts with a previous"
+  "'sycl_kernel_entry_point' kernel name %0 conflicts with a previous"
   " declaration">;
 
 def warn_cuda_maxclusterrank_sm_90 : Warning<

clang/include/clang/Sema/Sema.h

@@ -10348,6 +10348,8 @@ class Sema final : public SemaBase {
       PrintPragmaAttributeInstantiationPoint();
   }
   void PrintInstantiationStack();
+  void
+      PrintInstantiationStack(std::function<void(const PartialDiagnosticAt &)>);
 
   /// Determines whether we are currently in a context where
   /// template argument substitution failures are not considered

clang/include/clang/Sema/SemaSYCL.h

@@ -28,6 +28,10 @@ class SemaSYCL : public SemaBase {
 public:
   SemaSYCL(Sema &S);
 
+  using ContextNotes = SmallVector<PartialDiagnosticAt, 1>;
+  llvm::DenseMap<CanonicalDeclPtr<const FunctionDecl>, ContextNotes>
+      SYCLKernelEntryContextNotes;
+
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as device code".
   ///

clang/lib/Sema/SemaDecl.cpp

@@ -16069,9 +16069,9 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
       FD->setInvalidDecl();
     } else if (Body) {
       StmtResult SR = SYCL().BuildSYCLKernelCallStmt(FD, Body);
-      if (SR.isInvalid())
-        return nullptr;
-      Body = SR.get();
+      if (!SR.isInvalid()) {
+        Body = SR.get();
+      }
     }
   }
 

clang/lib/Sema/SemaSYCL.cpp

@@ -346,16 +346,12 @@ void SemaSYCL::CheckSYCLEntryPointFunctionDecl(FunctionDecl *FD) {
   if (!FD->isInvalidDecl() && !FD->isDependentContext()) {
     const SYCLKernelInfo *SKI =
         getASTContext().findSYCLKernelInfo(SKEPAttr->getKernelName());
-    if (SKI) {
-      if (!declaresSameEntity(FD, SKI->GetKernelEntryPointDecl())) {
-        // FIXME: This diagnostic should include the origin of the kernel
-        // FIXME: names; not just the locations of the conflicting declarations.
-        Diag(FD->getLocation(), diag::err_sycl_kernel_name_conflict);
-        Diag(SKI->GetKernelEntryPointDecl()->getLocation(),
-             diag::note_previous_declaration);
-        FD->setInvalidDecl();
-      }
-    } else {
+    if (!SKI) {
+      // Note: In order to not interfere with SFINAE, we delay the diagnostic of
+      // conflicting names to when we act on the attribute.
+      ContextNotes &Notes = SYCLKernelEntryContextNotes[FD];
+      SemaRef.PrintInstantiationStack(
+          [&](const PartialDiagnosticAt &PD) { Notes.push_back(PD); });
       getASTContext().registerSYCLEntryPointFunction(FD);
     }
   }
@@ -373,8 +369,20 @@ StmtResult SemaSYCL::BuildSYCLKernelCallStmt(FunctionDecl *FD, Stmt *Body) {
   // stored declaration matches.
   const SYCLKernelInfo &SKI =
         getASTContext().getSYCLKernelInfo(SKEPAttr->getKernelName());
-  if (!declaresSameEntity(SKI.GetKernelEntryPointDecl(), FD))
-    llvm::report_fatal_error("SYCL kernel name conflict");
+  if (!declaresSameEntity(SKI.GetKernelEntryPointDecl(), FD)) {
+    Diag(FD->getLocation(), diag::err_sycl_kernel_name_conflict)
+        << SKEPAttr->getKernelName();
+    Diag(SKI.GetKernelEntryPointDecl()->getLocation(),
+         diag::note_previous_declaration);
+    for (const PartialDiagnosticAt &PD :
+         SYCLKernelEntryContextNotes.at(SKI.GetKernelEntryPointDecl())) {
+      DiagnosticBuilder Builder(
+          SemaRef.Diags.Report(PD.first, PD.second.getDiagID()));
+      PD.second.Emit(Builder);
+    }
+    FD->setInvalidDecl();
+    return {/*Invalid=*/true};
+  }
 
   using ParmDeclMap = OutlinedFunctionDeclBodyInstantiator::ParmDeclMap;
   ParmDeclMap ParmMap;