[libcxx-commits] [libcxx] [libc++] Improve diagnostic for libcxxabi missing from the runtimes (PR #208274)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

<details>
<summary>Changes</summary>

When libc++ is configured to use libc++abi as an ABI library but libcxxabi is not part of the runtimes, we'd end up with a confusing build error about a missing <cxxabi.h> header. Instead, diagnose at CMake configuration time.

Closes #<!-- -->136480

---
Full diff: https://github.com/llvm/llvm-project/pull/208274.diff


1 Files Affected:

- (modified) libcxx/cmake/Modules/HandleLibCXXABI.cmake (+6) 


``````````diff
diff --git a/libcxx/cmake/Modules/HandleLibCXXABI.cmake b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
index 52236f473f35d..4b4ff7c7f9d5f 100644
--- a/libcxx/cmake/Modules/HandleLibCXXABI.cmake
+++ b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
@@ -148,6 +148,12 @@ elseif ("${LIBCXX_CXX_ABI}" STREQUAL "libcxxabi")
     add_library(libcxx-abi-static-objects ALIAS cxxabi_static_objects)
   endif()
 
+  if (NOT TARGET cxxabi_static AND NOT TARGET cxxabi_shared
+      AND NOT TARGET cxxabi_static_objects AND NOT TARGET cxxabi_shared_objects)
+    message(FATAL_ERROR "Can't find any libc++abi target but LIBCXX_CXX_ABI is set to libcxxabi, "
+                        "did you forget to include libcxxabi in LLVM_ENABLE_RUNTIMES?")
+  endif()
+
 # Link against a system-provided libc++abi
 elseif ("${LIBCXX_CXX_ABI}" STREQUAL "system-libcxxabi")
   if(NOT LIBCXX_CXX_ABI_INCLUDE_PATHS)

``````````

</details>


https://github.com/llvm/llvm-project/pull/208274