[clang] [HLSL] Add StructuredBuffer to external sema source (PR #106316)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-ubuntu-fast` running on `sie-linux-worker` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/144/builds/6775

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clang :: AST/HLSL/StructuredBuffer-AST.hlsl' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/clang -cc1 -internal-isystem /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-library -x hlsl -ast-dump -DEMPTY /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl | /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck -check-prefix=EMPTY /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/clang -cc1 -internal-isystem /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-library -x hlsl -ast-dump -DEMPTY /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck -check-prefix=EMPTY /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
RUN: at line 2: /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/clang -cc1 -internal-isystem /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-library -x hlsl -ast-dump /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl | /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/clang -cc1 -internal-isystem /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-library -x hlsl -ast-dump /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl:33:16: error: CHECK-NEXT: expected string not found in input
// CHECK-NEXT: FieldDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> implicit h 'element_type *'
               ^
<stdin>:33:63: note: scanning from here
| | |-FinalAttr 0x5c786e4fc708 <<invalid sloc>> Implicit final
                                                              ^
<stdin>:34:6: note: possible intended match here
| | |-FieldDecl 0x5c786e517e78 <<invalid sloc>> <invalid sloc> implicit h 'element_type * [[hlsl::resource_class(UAV)]]':'element_type *'
     ^

Input file: <stdin>
Check file: /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/test/AST/HLSL/StructuredBuffer-AST.hlsl

-dump-input=help explains the following input dump.

Input was:
<<<<<<
           1: TranslationUnitDecl 0x5c786e4d45c8 <<invalid sloc>> <invalid sloc> 
           2: |-NamespaceDecl 0x5c786e4d4ee8 <<invalid sloc>> <invalid sloc> implicit hlsl 
           3: | |-TypeAliasTemplateDecl 0x5c786e4d5240 <<invalid sloc>> <invalid sloc> implicit vector 
           4: | | |-TemplateTypeParmDecl 0x5c786e4d4f70 <<invalid sloc>> <invalid sloc> class depth 0 index 0 element 
           5: | | | `-TemplateArgument type 'float' 
           6: | | | `-BuiltinType 0x5c786e4d47d0 'float' 
           7: | | |-NonTypeTemplateParmDecl 0x5c786e4d5070 <<invalid sloc>> <invalid sloc> 'int' depth 0 index 1 element_count 
           8: | | | `-TemplateArgument expr '4' 
           9: | | | `-IntegerLiteral 0x5c786e4d50c8 <<invalid sloc>> 'int' 4 
          10: | | `-TypeAliasDecl 0x5c786e4d51e0 <<invalid sloc>> <invalid sloc> implicit vector 'vector<element, element_count>' 
          11: | | `-DependentSizedExtVectorType 0x5c786e4d5190 'vector<element, element_count>' dependent <invalid sloc> 
          12: | | |-TemplateTypeParmType 0x5c786e4d4ff0 'element' dependent depth 0 index 0 
          13: | | | `-TemplateTypeParm 0x5c786e4d4f70 'element' 
          14: | | `-DeclRefExpr 0x5c786e4d5128 <<invalid sloc>> 'int' lvalue NonTypeTemplateParm 0x5c786e4d5070 'element_count' 'int' 
          15: | |-ClassTemplateDecl 0x5c786e4d5438 <<invalid sloc>> <invalid sloc> implicit RWBuffer 
          16: | | |-TemplateTypeParmDecl 0x5c786e4d5398 <<invalid sloc>> <invalid sloc> class depth 0 index 0 element_type 
          17: | | `-CXXRecordDecl 0x5c786e4d5298 <<invalid sloc>> <invalid sloc> implicit <undeserialized declarations> class RWBuffer 
          18: | | `-FinalAttr 0x5c786e4d5340 <<invalid sloc>> Implicit final 
          19: | |-ClassTemplateDecl 0x5c786e4fc428 <<invalid sloc>> <invalid sloc> implicit RasterizerOrderedBuffer 
          20: | | |-TemplateTypeParmDecl 0x5c786e4fc390 <<invalid sloc>> <invalid sloc> class depth 0 index 0 element_type 
          21: | | `-CXXRecordDecl 0x5c786e4fc290 <<invalid sloc>> <invalid sloc> implicit <undeserialized declarations> class RasterizerOrderedBuffer 
          22: | | `-FinalAttr 0x5c786e4fc338 <<invalid sloc>> Implicit final 
...

```

</details>

https://github.com/llvm/llvm-project/pull/106316