[llvm] Update the libc BUILD.bazel file with selects for Windows builds. (PR #131172)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Brian Ledger (bashi-bazouk)

<details>
<summary>Changes</summary>

The Windows toolchain needs to build libc targets in order to support libc++. Currently, some targets fail to resolve, due to non-exhaustive select statements, not accounting for Windows builds.

This change adds clauses to select statements so that Windows builds can proceed.

Additionally, `__support_osutil_exit`, is configured to pass nothing to `srcs` for non-Linux builds. `__support_osutil_exit `is unconditionally included in the transitive dependencies of `extern_libc_shared`. 

---
Full diff: https://github.com/llvm/llvm-project/pull/131172.diff


1 Files Affected:

- (modified) utils/bazel/llvm-project-overlay/libc/BUILD.bazel (+6-1) 


``````````diff
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 757db65ca8a77..25a9736b3671e 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -1319,6 +1319,7 @@ libc_support_library(
             "src/__support/OSUtil/linux/aarch64/syscall.h",
             "src/__support/OSUtil/linux/x86_64/syscall.h",
         ],
+	"@platforms//os:windows": [],
     }),
     deps = [
         ":__support_common",
@@ -1360,6 +1361,7 @@ libc_support_library(
     textual_hdrs = select({
         "@platforms//os:macos": ["src/__support/OSUtil/darwin/io.h"],
         "@platforms//os:linux": ["src/__support/OSUtil/linux/io.h"],
+	"@platforms//os:windows": ["src/__support/OSUtil/windows/io.h"],
     }),
     deps = [
         ":__support_common",
@@ -1371,7 +1373,10 @@ libc_support_library(
 
 libc_support_library(
     name = "__support_osutil_exit",
-    srcs = ["src/__support/OSUtil/linux/exit.cpp"],
+    srcs = select({
+        "@platforms//os:linux": ["src/__support/OSUtil/linux/exit.cpp"],
+	"//condition:default": [],
+    }),
     hdrs = ["src/__support/OSUtil/exit.h"],
     target_compatible_with = select({
         "@platforms//os:linux": [],

``````````

</details>


https://github.com/llvm/llvm-project/pull/131172