v to c: Boolean type error in gcc.

[CryingN]

Describe the bug

I tried compiling with the v compiler targeting clang and gcc separately. An error occurred when the gcc version was 15.2.1. I was able to continue compiling with gcc after deleting the following code:

#ifndef CUSTOM_DEFINE_no_bool
        #ifndef __cplusplus
                #ifndef bool
                        #ifdef CUSTOM_DEFINE_4bytebool
                                typedef int bool;
                        #else
                                typedef u8 bool;
                        #endif
                        #define true 1
                        #define false 0
                #endif
        #endif
#endif

Reproduction Steps

println("hello")

Expected Behavior

[root_cn@archlinux test_bool]$ cat easy.v
println("hello")
[root_cn@archlinux test_bool]$ v easy.v -o easy.c -cc gcc | gcc easy.c
[root_cn@archlinux test_bool]$ ./a.out
hello

Current Behavior

[root_cn@archlinux test_bool]$ cat easy.v
println("hello")
[root_cn@archlinux test_bool]$ v easy.v -o easy.c -cc gcc | gcc easy.c
easy.c:118:44: 错误：声明指定了两个以上的数据类型
  118 |                                 typedef u8 bool;
      |                                            ^~~~
easy.c:118:33: 警告：空声明中类型名无用
  118 |                                 typedef u8 bool;
      |                                 ^~~~~~~

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.12 0458303

Environment details (OS name and version, etc.)

V full version	V 0.4.12 0458303
OS	linux, Linux version 6.17.8-arch1-1 (linux@archlinux) (gcc (GCC) 15.2.1 20251112, GNU ld (GNU Binutils) 2.45.1) #1 SMP PREEMPT_DYNAMIC Fri, 14 Nov 2025 06:54:20 +0000
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz
Memory	0.34GB/7.51GB
V executable	/home/root_cn/work/vlang/v/v
V last modified time	2025-11-21 15:05:51
V home dir	OK, value: /home/root_cn/work/vlang/v
VMODULES	OK, value: /home/root_cn/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/root_cn
Git version	git version 2.52.0
V git status	weekly.2025.45-103-g0458303e
.git/config present	true
cc version	cc (GCC) 15.2.1 20251112
gcc version	gcc (GCC) 15.2.1 20251112
clang version	clang version 21.1.5
tcc version	tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (GNU libc) 2.42

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[gechandesu]

True, but this is not a bug.

$ pwd
/tmp
$ v version
V 0.4.12 0c7de2e
$ gcc --version
gcc (GCC) 15.2.1 20250813
Copyright (C) 2025 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cat easy.v
println("hello")
$ v easy.v -cc gcc -o easy.c
$ gcc easy.c
easy.c:118:44: error: two or more data types in declaration specifiers
  118 |                                 typedef u8 bool;
      |                                            ^~~~
easy.c:118:33: warning: useless type name in empty declaration
  118 |                                 typedef u8 bool;
      |                                 ^~~~~~~

V does not run just gcc SOUCRE.c. This is what actually V does:

$ v easy.v -cc gcc -showcc -keepc
> C compiler cmd: 'gcc' '@/tmp/v_1000/easy.tmp.c.rsp'
> C compiler response file "/tmp/v_1000/easy.tmp.c.rsp":
  -fwrapv -o '/tmp/easy' -D GC_THREADS=1 -D GC_BUILTIN_ATOMIC=1 -I "/home/ge/.vlang/thirdparty/libgc/include" "/tmp/v_1000/easy.tmp.c" -std=gnu99 -D_DEFAULT_SOURCE "/home/ge/.vlang/thirdparty/tcc/lib/libgc.a" -ldl -lpthread

(note the -showcc and -keepc flags)

With printed cc flags program compiles with no issues:

$ gcc -fwrapv -o '/tmp/easy' -D GC_THREADS=1 -D GC_BUILTIN_ATOMIC=1 -I "/home/ge/.vlang/thirdparty/libgc/include" "/tmp/v_1000/easy.tmp.c" -std=gnu99 -D_DEFAULT_SOURCE "/home/ge/.vlang/thirdparty/tcc/lib/libgc.a" -ldl -lpthread
$ ./easy
hello

V's codegen produces the C99 standard code, so -std=gnu99 must be used.