[clang] [ParserHLSL] Attempt to parse HLSL annotations on Field Decls. (PR #96346)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-hlsl

Author: Joshua Batista (bob80905)

<details>
<summary>Changes</summary>

`MaybeParseHLSLAnnotations` should be run on Field Decls instead of just assuming that any colon after a field decl is a bitfield. In the case that HLSL is the language, the code after the colon may be an annotation. This PR gives the parser a chance to parse the subsequent text as if it was an HLSL annotation.

---
Full diff: https://github.com/llvm/llvm-project/pull/96346.diff


2 Files Affected:

- (modified) clang/lib/Parse/ParseDeclCXX.cpp (+3) 
- (added) clang/test/ParserHLSL/hlsl_annotations_on_struct_members.hlsl (+30) 


``````````diff
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index d02548f6441f9..c4a4657cbd04f 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2646,6 +2646,9 @@ bool Parser::ParseCXXMemberDeclaratorBeforeInitializer(
   else
     DeclaratorInfo.SetIdentifier(nullptr, Tok.getLocation());
 
+  if (getLangOpts().HLSL)
+    MaybeParseHLSLAnnotations(DeclaratorInfo);
+
   if (!DeclaratorInfo.isFunctionDeclarator() && TryConsumeToken(tok::colon)) {
     assert(DeclaratorInfo.isPastIdentifier() &&
            "don't know where identifier would go yet?");
diff --git a/clang/test/ParserHLSL/hlsl_annotations_on_struct_members.hlsl b/clang/test/ParserHLSL/hlsl_annotations_on_struct_members.hlsl
new file mode 100644
index 0000000000000..f1e258b0d853c
--- /dev/null
+++ b/clang/test/ParserHLSL/hlsl_annotations_on_struct_members.hlsl
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-compute -x hlsl -o - %s -verify
+
+// previously, this test would result in an error shown below on the line that 
+// declares variable a in struct Eg9:
+// error: use of undeclared identifier
+//     'SV_DispatchThreadID'
+// This is because the annotation is parsed as if it was a c++ bit field, and an identifier
+// that represents an integer is expected, but not found.
+
+// This test ensures that hlsl annotations are attempted to be parsed when parsing struct decls.
+// Ideally, we'd validate this behavior by ensuring the annotation is parsed and properly
+// attached as an attribute to the member in the struct in the AST. However, in this case
+// this can't happen presently because there are other issues with annotations on field decls.
+// This test just ensures we make progress by moving the validation error from the realm of
+// C++ and expecting bitfields, to HLSL and a specialized error for the recognized annotation.
+
+struct Eg9{
+// expected-error at +1{{attribute 'SV_DispatchThreadID' only applies to parameter}}
+  int a : SV_DispatchThreadID;
+};
+Eg9 e9;
+
+
+RWBuffer<int> In : register(u1);
+
+
+[numthreads(1,1,1)]
+void main() {
+  In[0] = e9.a;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/96346