[libcxx-commits] [libcxx] [libcxx][ci] Set CMAKE_C_COMPILER_TARGET for all Arm/AArch64 builds (PR #192645)

[David Spickett via libcxx-commits]

https://github.com/DavidSpickett created https://github.com/llvm/llvm-project/pull/192645

As requested on #192493.

This is not strictly needed, but setting only CMAKE_CXX_COMPILER_TARGET does look suspicious. Especially as we often set both CXX_FLAGS and C_FLAGS in the same builds.

Set both C_COMPILER_TARGET and CXX_COMPILER_TARGET so on one has to wonder if it's the cause of a problem.

(note that picolibc builds are already setting both)

>From 4f73c178d8dfa470cb97824304596c91492ebadc Mon Sep 17 00:00:00 2001
From: David Spickett <david.spickett at arm.com>
Date: Fri, 17 Apr 2026 12:46:42 +0000
Subject: [PATCH] [libcxx][ci] Set CMAKE_C_COMPILER_TARGET for all Arm/AArch64
 builds

This is not strictly needed but setting only CMAKE_CXX_COMPILER_TARGET
does look suspicious. Especially as we often set CXX_FLAGS and C_FLAGS.
Set both so on one wastes time looking into it as a potential problem.

Note that picolibc builds are already setting both.
---
 libcxx/cmake/caches/AArch64.cmake                  | 1 +
 libcxx/cmake/caches/Armv7Arm.cmake                 | 1 +
 libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake | 1 +
 libcxx/cmake/caches/Armv8Arm.cmake                 | 1 +
 libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake | 1 +
 5 files changed, 5 insertions(+)

diff --git a/libcxx/cmake/caches/AArch64.cmake b/libcxx/cmake/caches/AArch64.cmake
index d813273584b0f..b9d3adad0a406 100644
--- a/libcxx/cmake/caches/AArch64.cmake
+++ b/libcxx/cmake/caches/AArch64.cmake
@@ -1 +1,2 @@
 set(CMAKE_CXX_COMPILER_TARGET "aarch64-linux-gnu" CACHE STRING "")
+set(CMAKE_C_COMPILER_TARGET "aarch64-linux-gnu" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv7Arm.cmake b/libcxx/cmake/caches/Armv7Arm.cmake
index be8f9ff74a8e4..994ff4146ff34 100644
--- a/libcxx/cmake/caches/Armv7Arm.cmake
+++ b/libcxx/cmake/caches/Armv7Arm.cmake
@@ -1,5 +1,6 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv7l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
+set(CMAKE_C_COMPILER_TARGET "armv7l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake b/libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake
index 5ddfa15d77a49..72c43e9721978 100644
--- a/libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake
+++ b/libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake
@@ -1,5 +1,6 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv7l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
+set(CMAKE_C_COMPILER_TARGET "armv7l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
diff --git a/libcxx/cmake/caches/Armv8Arm.cmake b/libcxx/cmake/caches/Armv8Arm.cmake
index e0379b5870bdf..448bb73c2e5bf 100644
--- a/libcxx/cmake/caches/Armv8Arm.cmake
+++ b/libcxx/cmake/caches/Armv8Arm.cmake
@@ -1,4 +1,5 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv8l-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_C_COMPILER_TARGET "armv8l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake b/libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake
index b0a53484961e4..eaf87b1a9434c 100644
--- a/libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake
+++ b/libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake
@@ -1,5 +1,6 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv8l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
+set(CMAKE_C_COMPILER_TARGET "armv8l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")