[clang] [HLSL] Allow EmptyDecl in cbuffer/tbuffer (PR #128250)

[Chris B via cfe-commits]

https://github.com/llvm-beanz created https://github.com/llvm/llvm-project/pull/128250

We do handle EmptyDecls in codegen already as of #124886, but we were blocking them in Sema. EmptyDecls tend to be caused by extra semicolons which are not illegal.

Fixes #128238

>From 98d8a84c508d743cb366db7a16b2b813f0c595d0 Mon Sep 17 00:00:00 2001
From: Chris Bieneman <chris.bieneman at me.com>
Date: Fri, 21 Feb 2025 17:47:12 -0600
Subject: [PATCH] [HLSL] Allow EmptyDecl in cbuffer/tbuffer

We do handle EmptyDecls in codegen already as of #124886, but we were
blocking them in Sema. EmptyDecls tend to be caused by extra semicolons
which are not illegal.

Fixes #128238
---
 clang/lib/Parse/ParseHLSL.cpp     |  2 +-
 clang/test/SemaHLSL/cb_error.hlsl | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Parse/ParseHLSL.cpp b/clang/lib/Parse/ParseHLSL.cpp
index 443bf2b9ec626..612e1ab0084ff 100644
--- a/clang/lib/Parse/ParseHLSL.cpp
+++ b/clang/lib/Parse/ParseHLSL.cpp
@@ -30,7 +30,7 @@ static bool validateDeclsInsideHLSLBuffer(Parser::DeclGroupPtrTy DG,
   // Only allow function, variable, record decls inside HLSLBuffer.
   for (DeclGroupRef::iterator I = Decls.begin(), E = Decls.end(); I != E; ++I) {
     Decl *D = *I;
-    if (isa<CXXRecordDecl, RecordDecl, FunctionDecl, VarDecl>(D))
+    if (isa<CXXRecordDecl, RecordDecl, FunctionDecl, VarDecl, EmptyDecl>(D))
       continue;
 
     // FIXME: support nested HLSLBuffer and namespace inside HLSLBuffer.
diff --git a/clang/test/SemaHLSL/cb_error.hlsl b/clang/test/SemaHLSL/cb_error.hlsl
index 133adeeb2068b..95c917a9bb9ee 100644
--- a/clang/test/SemaHLSL/cb_error.hlsl
+++ b/clang/test/SemaHLSL/cb_error.hlsl
@@ -47,3 +47,15 @@ tbuffer B {
   // expected-error at +1 {{unknown type name 'flaot'}}
   flaot f;
 }
+
+// None of these should produce an error!
+cbuffer EmptyCBuffer {}
+
+cbuffer EmptyDeclCBuffer {
+  ;
+}
+
+cbuffer EmptyDecl2CBuffer {
+  ;
+  int X;
+}