[llvm] Use default instead of a specific case to fix the MSVC warning in sysinfo.cc (PR #149159)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-third-party-benchmark

Author: Daniel Paoliello (dpaoliello)

<details>
<summary>Changes</summary>

#<!-- -->147357 attempted to fix an MSVC in sysinfo.cc by adding a `case` block for a missing enum value.

However, this resulted in [CI failures](https://github.com/llvm/llvm-project/pull/147357#issuecomment-3079709852):
```
4.170 [148/4/9] Building CXX object third-party/benchmark/src/CMakeFiles/benchmark.dir/sysinfo.cc.obj
FAILED: third-party/benchmark/src/CMakeFiles/benchmark.dir/sysinfo.cc.obj 
C:\Users\tcwg\scoop\shims\ccache.exe C:\Users\tcwg\scoop\apps\llvm-arm64\current\bin\clang-cl.exe  /nologo -TP -DBENCHMARK_STATIC_DEFINE -DEXPERIMENTAL_KEY_INSTRUCTIONS -DHAVE_STD_REGEX -DHAVE_STEADY_CLOCK -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_GLIBCXX_ASSERTIONS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -IC:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/build/third-party/benchmark/src -IC:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/llvm-project/third-party/benchmark/src -IC:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/build/include -IC:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/llvm-project/llvm/include -IC:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/llvm-project/third-party/benchmark/include /DWIN32 /D_WINDOWS   /Zc:inline /Zc:__cplusplus /Oi /Brepro /bigobj /permissive- -Werror=unguarded-availability-new   -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported /Gw /W4  -EHs-  -EHa- /O2 /Ob2  -std:c++14 -MD -UNDEBUG /showIncludes /Fothird-party/benchmark/src/CMakeFiles/benchmark.dir/sysinfo.cc.obj /Fdthird-party\benchmark\src\CMakeFiles\benchmark.dir\benchmark.pdb -c -- C:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/llvm-project/third-party/benchmark/src/sysinfo.cc
C:/Users/tcwg/llvm-worker/flang-arm64-windows-msvc/llvm-project/third-party/benchmark/src/sysinfo.cc(374,12): error: use of undeclared identifier 'CacheUnknown'
  374 |       case CacheUnknown:
      |            ^
1 error generated.
```

The root cause is that the enum being switched on is defined in the Windows SDK, so depending on which version of the SDK you are using `CacheUnknown` may or may not be defined.

The correct fix here is to use a `default` block in the switch statement instead.

---
Full diff: https://github.com/llvm/llvm-project/pull/149159.diff


1 Files Affected:

- (modified) third-party/benchmark/src/sysinfo.cc (+1-1) 


``````````diff
diff --git a/third-party/benchmark/src/sysinfo.cc b/third-party/benchmark/src/sysinfo.cc
index 837be8f9cf891..d1ae6cc82b943 100644
--- a/third-party/benchmark/src/sysinfo.cc
+++ b/third-party/benchmark/src/sysinfo.cc
@@ -371,7 +371,7 @@ std::vector<CPUInfo::CacheInfo> GetCacheSizesWindows() {
       case CacheTrace:
         C.type = "Trace";
         break;
-      case CacheUnknown:
+      default:
         C.type = "Unknown";
         break;
     }

``````````

</details>


https://github.com/llvm/llvm-project/pull/149159