[libc-commits] [libc] [libc] Update libc_errno to work correctly in both overlay and full build modes. (PR #80177)

[via libc-commits]

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@@ -1,9 +1,20 @@
+# If we are in full build mode, we will provide the errno definition ourselves,
+# and if we are in overlay mode, we will just re-use the system's errno.
+# We are passing LIBC_FULL_BUILD flag in full build mode so that the
+# implementation of libc_errno will know if we are in full build mode or not.
+set(full_build_flag "")
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lntue wrote:

I think @michaelrj-google also has some usage for full build mode detection inside the implementations, so I will probably move this to `_get_common_compile_options` later.

https://github.com/llvm/llvm-project/pull/80177