[Clang] Fix missed initializer instantiation bug for variable templates

[Clang] Fix missed initializer instantiation bug for variable templates

Author: dty2

clang/docs/ReleaseNotes.rst

@@ -604,6 +604,7 @@ Bug Fixes to C++ Support
 - Clang now issues an error when placement new is used to modify a const-qualified variable
   in a ``constexpr`` function. (#GH131432)
 - Clang now emits a warning when class template argument deduction for alias templates is used in C++17. (#GH133806)
+- Fix missing initializer for inline static template member with auto type caused by delayed template instantiation. (#GH138122)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -6028,11 +6028,11 @@ void Sema::BuildVariableInstantiation(
   Context.setStaticLocalNumber(NewVar, Context.getStaticLocalNumber(OldVar));
 
   // Figure out whether to eagerly instantiate the initializer.
-  if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
-    // We're producing a template. Don't instantiate the initializer yet.
-  } else if (NewVar->getType()->isUndeducedType()) {
+  if (NewVar->getType()->isUndeducedType()) {
     // We need the type to complete the declaration of the variable.
     InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
+  } else if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
+    // We're producing a template. Don't instantiate the initializer yet.
   } else if (InstantiatingSpecFromTemplate ||
              (OldVar->isInline() && OldVar->isThisDeclarationADefinition() &&
               !NewVar->isThisDeclarationADefinition())) {

clang/test/CodeGenCXX/cxx1z-inline-variables.cpp

@@ -1,5 +1,19 @@
 // RUN: %clang_cc1 -std=c++1z %s -emit-llvm -o - -triple x86_64-linux-gnu | FileCheck %s
 
+template <typename T> struct InlineAuto {
+  template <typename G> inline static auto var = 5;
+};
+int inlineauto = InlineAuto<int>::var<int>;
+// CHECK: @_ZN10InlineAutoIiE3varIiEE = {{.*}}i32 5{{.*}}comdat
+//
+template <typename> struct PartialInlineAuto {
+  template <typename, typename> inline static auto var = 6;
+  template <typename T> inline static auto var<int, T> = 7;
+};
+
+int partialinlineauto = PartialInlineAuto<int>::var<int, int>;
+// CHECK: @_ZN17PartialInlineAutoIiE3varIiiEE = {{.*}}i32 7{{.*}}comdat
+
 struct Q {
   // CHECK: @_ZN1Q1kE = linkonce_odr constant i32 5, comdat
   static constexpr int k = 5;

clang/test/SemaTemplate/cxx17-inline-variables.cpp

@@ -27,3 +27,15 @@ template <typename T> constexpr int A<T>::n = sizeof(A) + sizeof(T);
 template <typename T> inline constexpr int A<T>::m = sizeof(A) + sizeof(T);
 static_assert(A<int>().f() == 5);
 static_assert(A<int>().g() == 5);
+
+template <typename T> struct InlineAuto {
+  template <typename G> inline static auto var = 5;
+};
+
+template <typename> struct PartialInlineAuto {
+  template <typename, typename> inline static auto var = 6;
+  template <typename T> inline static auto var<int, T> = 7;
+};
+
+int inlineauto = InlineAuto<int>::var<int>;
+int partialinlineauto = PartialInlineAuto<int>::var<int, int>;

clang/tools/driver/driver.cpp

@@ -72,7 +72,7 @@ std::string GetExecutablePath(const char *Argv0, bool CanonicalPrefixes) {
 
   // This just needs to be some symbol in the binary; C++ doesn't
   // allow taking the address of ::main however.
-  void *P = (void*) (intptr_t) GetExecutablePath;
+  void *P = (void *)(intptr_t)GetExecutablePath;
   return llvm::sys::fs::getMainExecutable(Argv0, P);
 }
 
@@ -105,10 +105,10 @@ static void insertTargetAndModeArgs(const ParsedClangName &NameParts,
   }
 
   if (NameParts.TargetIsValid) {
-    const char *arr[] = {"-target", GetStableCStr(SavedStrings,
-                                                  NameParts.TargetPrefix)};
-    ArgVector.insert(ArgVector.begin() + InsertionPoint,
-                     std::begin(arr), std::end(arr));
+    const char *arr[] = {"-target",
+                         GetStableCStr(SavedStrings, NameParts.TargetPrefix)};
+    ArgVector.insert(ArgVector.begin() + InsertionPoint, std::begin(arr),
+                     std::end(arr));
   }
 }
 
@@ -328,8 +328,8 @@ int clang_main(int Argc, char **Argv, const llvm::ToolContext &ToolContext) {
   // actions.
   DiagOpts->DiagnosticSuppressionMappingsFile.clear();
 
-  TextDiagnosticPrinter *DiagClient
-    = new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
+  TextDiagnosticPrinter *DiagClient =
+      new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
   FixupDiagPrefixExeName(DiagClient, ProgName);
 
   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
@@ -439,8 +439,8 @@ int clang_main(int Argc, char **Argv, const llvm::ToolContext &ToolContext) {
   if (::getenv("FORCE_CLANG_DIAGNOSTICS_CRASH"))
     llvm::dbgs() << llvm::getBugReportMsg();
   if (FailingCommand != nullptr &&
-    TheDriver.maybeGenerateCompilationDiagnostics(CommandStatus, ReproLevel,
-                                                  *C, *FailingCommand))
+      TheDriver.maybeGenerateCompilationDiagnostics(CommandStatus, ReproLevel,
+                                                    *C, *FailingCommand))
     Res = 1;
 
   Diags.getClient()->finish();