fix(klibc): also check __clang__ when detecting gcc

[Tang-Haojin]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

src/klibc/rt_vsnprintf_std.c 中通过 __GNUC__ 宏来在 gcc 中临时关闭 Wmaybe-uninitialized，但 clang 编译器也会定义该宏：

$ clang -dM -E -x c /dev/null | grep __GNUC__
#define __GNUC__ 4

从而在 clang 编译时出现判断错误，clang 编译器报 Wunknown-warning-option：

src/klibc/rt_vsnprintf_std.c:598:32: warning: unknown warning group '-Wmaybe-uninitialized', ignored [-Wunknown-warning-option]
  598 | #pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
      |                                ^
1 warning generated.

你的解决方案是什么 (what is your solution)

增加对 __clang__ 宏的判断。

请提供验证的bsp和config (provide the config and bsp)

基于 virt riscv bsp 进行测试，但修改了部分代码以适配 clang 编译，相关修改如下。

diff --git a/bsp/qemu-virt64-riscv/rtconfig.py b/bsp/qemu-virt64-riscv/rtconfig.py
index 09d530af4a..7dec52efc0 100644
--- a/bsp/qemu-virt64-riscv/rtconfig.py
+++ b/bsp/qemu-virt64-riscv/rtconfig.py
@@ -3,15 +3,15 @@ import os
 # toolchains options
 ARCH        ='risc-v'
 CPU         ='virt64'
-CROSS_TOOL  ='gcc'
+CROSS_TOOL  ='llvm-riscv'
 
 RTT_ROOT = os.getenv('RTT_ROOT') or os.path.join(os.getcwd(), '..', '..')
 
 if os.getenv('RTT_CC'):
     CROSS_TOOL = os.getenv('RTT_CC')
 
-if  CROSS_TOOL == 'gcc':
-    PLATFORM    = 'gcc'
+if  CROSS_TOOL == 'llvm-riscv':
+    PLATFORM    = 'llvm-riscv'
     EXEC_PATH   = os.getenv('RTT_EXEC_PATH') or '/usr/bin'
 else:
     print('Please make sure your toolchains is GNU GCC!')
@@ -19,28 +19,28 @@ else:
 
 BUILD = 'debug'
 
-if PLATFORM == 'gcc':
+if PLATFORM == 'llvm-riscv':
     # toolchains
     PREFIX  = os.getenv('RTT_CC_PREFIX') or 'riscv64-unknown-elf-'
-    CC      = PREFIX + 'gcc'
-    CXX     = PREFIX + 'g++'
-    AS      = PREFIX + 'gcc'
-    AR      = PREFIX + 'ar'
-    LINK    = PREFIX + 'gcc'
+    CC      = PREFIX + 'clang'
+    CXX     = PREFIX + 'clang++'
+    AS      = PREFIX + 'clang'
+    AR      = PREFIX + 'llvm-ar'
+    LINK    = PREFIX + 'clang++'
     TARGET_EXT = 'elf'
     SIZE    = PREFIX + 'size'
     OBJDUMP = PREFIX + 'objdump'
     OBJCPY  = PREFIX + 'objcopy'
 
     DEVICE  = ' -mcmodel=medany -march=rv64imafdc -mabi=lp64 '
-    CFLAGS  = DEVICE + '-ffreestanding -flax-vector-conversions -Wno-cpp -fno-common -ffunction-sections -fdata-sections -fstrict-volatile-bitfields -fdiagnostics-color=always'
+    CFLAGS  = DEVICE + '-flax-vector-conversions -Wno-cpp -fno-common -ffunction-sections -fdata-sections -fdiagnostics-color=always -Xclang -fexperimental-max-bitint-width=65536'
     AFLAGS  = ' -c' + DEVICE + ' -x assembler-with-cpp -D__ASSEMBLY__ '
-    LFLAGS  = DEVICE + ' -nostartfiles -Wl,--gc-sections,-Map=rtthread.map,-cref,-u,_start -T link.lds' + ' -lsupc++ -lgcc -static'
+    LFLAGS  = DEVICE + ' -nostartfiles -Wl,--gc-sections,-Map=rtthread.map,-cref,-u,_start -T link.lds' + ' -stdlib=libstdc++ -lc -lsupc++ -lgcc -lstdc++ -static'
     CPATH   = ''
     LPATH   = ''
 
     if BUILD == 'debug':
-        CFLAGS += ' -O0 -ggdb -fvar-tracking '
+        CFLAGS += ' -O0 -ggdb '
         AFLAGS += ' -ggdb'
     else:
         CFLAGS += ' -O2 -Os'
diff --git a/components/libc/compilers/common/extension/SConscript b/components/libc/compilers/common/extension/SConscript
index 58e43dd62e..2f35bb0d47 100644
--- a/components/libc/compilers/common/extension/SConscript
+++ b/components/libc/compilers/common/extension/SConscript
@@ -9,7 +9,7 @@ group = []
 
 src += Glob('*.c')
 
-if rtconfig.PLATFORM not in ['gcc', 'llvm-arm']:
+if rtconfig.PLATFORM not in ['gcc', 'llvm-arm', 'llvm-riscv']:
     group = DefineGroup('Compiler', src, depend = [''], CPPPATH = CPPPATH)
 
 list = os.listdir(cwd)

• BSP: bsp/qemu-virt64-riscv

• .config: 默认配置，无需额外修改

• action:

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

[github-actions]

📌 Code Review Assignment

🏷️ Tag: kernel

Reviewers: @GorrayLi @ReviewSun @hamburger-os @lianux-mm @wdfk-prog @xu18838022837

Changed Files (Click to expand)

• src/klibc/rt_vsnprintf_std.c

---

📊 Current Review Status (Last Updated: 2025-09-01 14:43 CST)

• ⌛ @GorrayLi Pending Review
• ⌛ @ReviewSun Pending Review
• ⌛ @hamburger-os Pending Review
• ⌛ @lianux-mm Pending Review
• ⌛ @wdfk-prog Pending Review
• ⌛ @xu18838022837 Pending Review

---

📝 Review Instructions

1. 维护者可以通过单击此处来刷新审查状态: 🔄 刷新状态
   Maintainers can refresh the review status by clicking here: 🔄 Refresh Status

2. 确认审核通过后评论 LGTM/lgtm
   Comment LGTM/lgtm after confirming approval

3. PR合并前需至少一位维护者确认
   PR must be confirmed by at least one maintainer before merging

ℹ️ 刷新CI状态操作需要具备仓库写入权限。
ℹ️ Refresh CI status operation requires repository Write permission.

[Tang-Haojin]

看起来挂掉的 CI 似乎和这个 PR 无关。