0001-make-constexpr-and-nested-aliases-available.patch

From 57ad22a1a1dbad928c8a5f978e472ada1578b4b6 Mon Sep 17 00:00:00 2001
From: Christian Reinbold <dev@creinbold.de>
Date: Sat, 1 Nov 2025 14:19:48 +0100
Subject: [PATCH] make constexpr and nested aliases available

---
 tools/clang/include/clang/Basic/TokenKinds.def | 2 +-
 tools/clang/lib/Parse/ParseDecl.cpp            | 5 ++++-
 tools/clang/lib/SPIRV/DeclResultIdMapper.cpp   | 6 +++++-
 tools/clang/lib/SPIRV/SpirvEmitter.cpp         | 9 +++++----
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/tools/clang/include/clang/Basic/TokenKinds.def b/tools/clang/include/clang/Basic/TokenKinds.def
index 2267b12b7..7326f2d92 100644
--- a/tools/clang/include/clang/Basic/TokenKinds.def
+++ b/tools/clang/include/clang/Basic/TokenKinds.def
@@ -345,7 +345,7 @@ CXX11_KEYWORD(alignas               , 0)
 CXX11_KEYWORD(alignof               , 0)
 CXX11_KEYWORD(char16_t              , KEYNOMS18)
 CXX11_KEYWORD(char32_t              , KEYNOMS18)
-CXX11_KEYWORD(constexpr             , 0)
+CXX11_KEYWORD(constexpr             , KEYHLSL)
 CXX11_KEYWORD(decltype              , 0)
 CXX11_KEYWORD(noexcept              , 0)
 CXX11_KEYWORD(nullptr               , 0)
diff --git a/tools/clang/lib/Parse/ParseDecl.cpp b/tools/clang/lib/Parse/ParseDecl.cpp
index 4ca80fcec..aa7165268 100644
--- a/tools/clang/lib/Parse/ParseDecl.cpp
+++ b/tools/clang/lib/Parse/ParseDecl.cpp
@@ -3989,7 +3989,10 @@ HLSLReservedKeyword:
 
     // constexpr
     case tok::kw_constexpr:
-      if (getLangOpts().HLSL) { goto HLSLReservedKeyword; } // HLSL Change - reserved for HLSL
+      // We want the constexpr keyword available for using constexpr functions
+      // to initialize static const members.
+
+      // if (getLangOpts().HLSL) { goto HLSLReservedKeyword; }
       isInvalid = DS.SetConstexprSpec(Loc, PrevSpec, DiagID);
       break;
 
diff --git a/tools/clang/lib/SPIRV/DeclResultIdMapper.cpp b/tools/clang/lib/SPIRV/DeclResultIdMapper.cpp
index fd0fa8a3d..d25471f85 100644
--- a/tools/clang/lib/SPIRV/DeclResultIdMapper.cpp
+++ b/tools/clang/lib/SPIRV/DeclResultIdMapper.cpp
@@ -4814,7 +4814,11 @@ SpirvVariable *DeclResultIdMapper::createRayTracingNVStageVar(
 
 void DeclResultIdMapper::tryToCreateImplicitConstVar(const ValueDecl *decl) {
   const VarDecl *varDecl = dyn_cast<VarDecl>(decl);
-  if (!varDecl || !varDecl->isImplicit())
+  // Make sure to initialize static const members here. Since evaluateValue()
+  // also seems to handle constexpr members in templated and nested types, this
+  // change seems to be enough to support some basic metaprogramming idioms.
+  bool isStatic = varDecl->isStaticDataMember() && varDecl->hasInit();
+  if (!varDecl || !(varDecl->isImplicit() || isStatic))
     return;
 
   APValue *val = varDecl->evaluateValue();
diff --git a/tools/clang/lib/SPIRV/SpirvEmitter.cpp b/tools/clang/lib/SPIRV/SpirvEmitter.cpp
index 9addb6d22..43b4f0e06 100644
--- a/tools/clang/lib/SPIRV/SpirvEmitter.cpp
+++ b/tools/clang/lib/SPIRV/SpirvEmitter.cpp
@@ -1038,6 +1038,10 @@ void SpirvEmitter::doDecl(const Decl *decl) {
     declIdMapper.recordsSpirvTypeAlias(decl);
   } else if (isa<FunctionTemplateDecl>(decl)) {
     // nothing to do.
+  } else if (isa<TypeAliasDecl>(decl)) {
+    // nothing to do.
+  } else if (isa<TypeAliasTemplateDecl>(decl)) {
+    // nothing to do.
   } else if (isa<UsingDecl>(decl)) {
     // nothing to do.
   } else if (isa<UsingDirectiveDecl>(decl)) {
@@ -1820,10 +1824,7 @@ void SpirvEmitter::doRecordDecl(const RecordDecl *recordDecl) {
   // RecordDecl. For those defined in the translation unit,
   // their VarDecls do not have initializer.
   for (auto *subDecl : recordDecl->decls()) {
-    if (auto *varDecl = dyn_cast<VarDecl>(subDecl)) {
-      if (varDecl->isStaticDataMember() && varDecl->hasInit())
-        doVarDecl(varDecl);
-    } else if (auto *enumDecl = dyn_cast<EnumDecl>(subDecl)) {
+    if (auto *enumDecl = dyn_cast<EnumDecl>(subDecl)) {
       doEnumDecl(enumDecl);
     } else if (auto recordDecl = dyn_cast<RecordDecl>(subDecl)) {
       doRecordDecl(recordDecl);
-- 
2.51.0.windows.2