[202x] Fix nesting cbuffers in namespaces

docs/ReleaseNotes.md

@@ -63,6 +63,8 @@ line upon naming the release. Refer to previous for appropriate section names.
 - The `shared` and `uniform` keywords are removed in HLSL 202x, with
   compatibility warnings available for earlier language versions
   [#8482](https://github.com/microsoft/DirectXShaderCompiler/issues/8482).
+- Starting with HLSL 202x, `cbuffer` and `tbuffer` declarations and their
+  members belong to their enclosing namespace.
 
 #### SPIR-V
 

tools/clang/lib/Sema/SemaHLSL.cpp

@@ -15446,6 +15446,9 @@ HLSLBufferDecl::Create(ASTContext &C, DeclContext *lexicalParent, bool cbuffer,
                        std::vector<hlsl::UnusualAnnotation *> &BufferAttributes,
                        SourceLocation LBrace) {
   DeclContext *DC = C.getTranslationUnitDecl();
+  // In HLSL 202x, buffers and their members belong to the enclosing namespace.
+  if (C.getLangOpts().HLSLVersion >= hlsl::LangStd::v202x)
+    DC = lexicalParent;
   HLSLBufferDecl *result = ::new (C) HLSLBufferDecl(
       DC, cbuffer, constantbuffer, KwLoc, Id, IdLoc, BufferAttributes, LBrace);
   if (DC != lexicalParent) {

tools/clang/test/CodeGenDXIL/cbuffer.namespace.hlsl

@@ -0,0 +1,23 @@
+// RUN: %dxc -T ps_6_0 -E main -HV 202x %s | FileCheck %s
+
+// CHECK: ; cbuffer SceneConstants
+// CHECK: ; cbuffer SceneConstants
+// CHECK: ; Resource Bindings:
+// CHECK-DAG: ; SceneConstants{{ +}}cbuffer{{ +}}NA{{ +}}NA{{ +}}CB0{{ +}}cb3{{ +}}1
+// CHECK-DAG: ; SceneConstants{{ +}}cbuffer{{ +}}NA{{ +}}NA{{ +}}CB1{{ +}}cb4{{ +}}1
+
+namespace First {
+cbuffer SceneConstants : register(b3) {
+  float Value;
+}
+}
+
+namespace Second {
+cbuffer SceneConstants : register(b4) {
+  float Value;
+}
+}
+
+float4 main() : SV_Target {
+  return First::Value + Second::Value;
+}

tools/clang/test/CodeGenSPIRV/cbuffer.namespace.hlsl

@@ -0,0 +1,22 @@
+// RUN: %dxc -T ps_6_0 -E main -HV 202x -spirv -fcgl %s | FileCheck %s
+
+// CHECK-DAG: OpDecorate [[FIRST:%[^ ]+]] Binding 3
+// CHECK-DAG: OpDecorate [[SECOND:%[^ ]+]] Binding 4
+// CHECK-DAG: [[FIRST]] = OpVariable {{%[^ ]+}} Uniform
+// CHECK-DAG: [[SECOND]] = OpVariable {{%[^ ]+}} Uniform
+
+namespace First {
+cbuffer SceneConstants : register(b3) {
+  float Value;
+}
+}
+
+namespace Second {
+cbuffer SceneConstants : register(b4) {
+  float Value;
+}
+}
+
+float4 main() : SV_Target {
+  return First::Value + Second::Value;
+}

tools/clang/test/SemaHLSL/v202x/buffer-namespace-decl-context.hlsl

@@ -0,0 +1,35 @@
+// RUN: %dxc -T lib_6_3 -HV 202x -verify %s
+// RUN: %dxc -T lib_6_3 -HV 202x -ast-dump %s 2>&1 | FileCheck %s
+
+// expected-no-diagnostics
+
+namespace First {
+// CHECK: NamespaceDecl {{.*}} First
+// CHECK-NEXT: {{.*}}HLSLBufferDecl {{0x[0-9a-f]+}} <{{.*}}> {{.*}} cbuffer Constants
+cbuffer Constants {
+  float FirstValue;
+}
+
+// CHECK: HLSLBufferDecl {{0x[0-9a-f]+}} <{{.*}}> {{.*}} tbuffer Textures
+tbuffer Textures {
+  float FirstTextureValue;
+}
+}
+
+namespace Second {
+// CHECK: NamespaceDecl {{.*}} Second
+// CHECK-NEXT: {{.*}}HLSLBufferDecl {{0x[0-9a-f]+}} <{{.*}}> {{.*}} cbuffer Constants
+cbuffer Constants {
+  float SecondValue;
+}
+
+// CHECK: HLSLBufferDecl {{0x[0-9a-f]+}} <{{.*}}> {{.*}} tbuffer Textures
+tbuffer Textures {
+  float SecondTextureValue;
+}
+}
+
+float4 main() : SV_Target {
+  return First::FirstValue + First::FirstTextureValue +
+         Second::SecondValue + Second::SecondTextureValue;
+}