[clang] [HLSL] Vector Usual Arithmetic Conversions (PR #108659)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `clang` at step 6 "test-build-unified-tree-check-clang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/8762

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

```
Step 6 (test-build-unified-tree-check-clang) failure: test (failure)
******************** TEST 'Clang :: SemaHLSL/Language/UsualArithmeticConversions.hlsl' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.3-library -finclude-default-header -fnative-half-type /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/SemaHLSL/Language/UsualArithmeticConversions.hlsl -DERRORS -Wconversion -Wdouble-promotion -verify
+ /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.3-library -finclude-default-header -fnative-half-type /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/SemaHLSL/Language/UsualArithmeticConversions.hlsl -DERRORS -Wconversion -Wdouble-promotion -verify
RUN: at line 2: /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.3-library -std=hlsl2018 -finclude-default-header -fnative-half-type /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/SemaHLSL/Language/UsualArithmeticConversions.hlsl -DERRORS -Wconversion -Wdouble-promotion -verify
+ /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.3-library -std=hlsl2018 -finclude-default-header -fnative-half-type /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/SemaHLSL/Language/UsualArithmeticConversions.hlsl -DERRORS -Wconversion -Wdouble-promotion -verify
error: 'expected-warning' diagnostics seen but not expected: 
  (frontend): support for HLSL language version hlsl2018 is incomplete, recommend using hlsl202x instead
1 error generated.

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/108659