-dump-c-flags does not respect -o option

[thomas-mangin]

Describe the bug

When using both -dump-c-flags and the -o option, the file is well created in the current folder but the compilation_flags.rsp file reference what would have been the temporary location of the C file, not the one specified by -o.

Reproduction Steps

❯ v -cc gcc -dump-c-flags compilation_flags.rsp -keepc -o test.c test.v
❯ cat compilation_flags.rsp 
-fwrapv
-o "/Users/thomas/Code/github.com/ze-community/ze/main/test"
-D GC_BUILTIN_ATOMIC=1
-D MPROTECT_VDB=1
-D GC_THREADS=1
-I "/Users/thomas/Unix/local/v/master/thirdparty/libgc/include"
-x objective-c
"/private/tmp/v_501/test.tmp.c"
-x none
-std=c99
-D_DEFAULT_SOURCE
"/Users/thomas/Unix/local/v/master/thirdparty/tcc/lib/libgc.a"
-ldl
-lpthread

Expected Behavior

the generated compilation_flags.rsp has the right path for the file

Current Behavior

the file is generated in the tmp location

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.6 4475759

Environment details (OS name and version, etc.)

V full version: V 0.4.6 cc14272.4475759
OS: macos, macOS, 14.5, 23F79
Processor: 10 cpus, 64bit, little endian, Apple M1 Max

getwd: /Users/thomas/Code/github.com/ze-community/ze/main
vexe: /Users/thomas/Unix/local/v/master/v
vexe mtime: 2024-07-06 14:05:43

vroot: OK, value: /Users/thomas/Unix/local/v/master
VMODULES: OK, value: /Users/thomas/Unix/data/v/modules
VTMP: OK, value: /tmp/v_501

Git version: git version 2.45.2
Git vroot status: weekly.2024.27-25-g4475759c (5 commit(s) behind V master)
.git/config present: true

CC version: Apple clang version 15.0.0 (clang-1500.3.9.4)
thirdparty/tcc status: thirdparty-macos-arm64 5c1d002f

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[spytheman]

It does have the right flags. V always stores temporary files in the VTMP folder.

What -o x.c does, is move the generated .tmp.c file later, to its final location.
It also skips starting the C compiler.

-dump-c-flags has nothing to do with it, and it does work as it should, by storing the original flags that were going to be used.

[thomas-mangin]

@spytheman Thank you very much for such a quick answer.

I accept that the current behaviour accurately reflects the actions performed by V, and that altering the output could lead to a misinterpretation of the process, potentially causing other user issues.
I also note that users can easily edit the generated compiler file to change the C file location. Therefore, I have no objections to this closure and accept the current behaviour.

... That said, it is still not what a user without an understanding of the V internals would expect to see. When -o is used, the user probably intends to do "something" with the generated C code. Otherwise, they would not bother using the option, so it would have made sense for the generated compile command to reflect what they wanted to do.

I am surprised by this decision but accept that it would take time, perhaps best spent elsewhere.

Thank you for clarifying your position.

[medvednikov]

@thomas-mangin does clang or gcc have similar flags which respect -o ?

[thomas-mangin]

Hello @medvednikov - Thank you for joining this thread. I thought it closed after my last post.

I am sorry as I do not know the answer, nor do I understand why you asked the question.
Could you please help me understand your line of thinking please?

[medvednikov]

GitHub allows having a discussion in closed threads.

If clang or gcc have this behavior (-o applying to not only binary path), then we should mimic it and implement this. Then this thread will be re-opened.

[thomas-mangin]

Yes, we can continue this discussion. By closed, I thought the matter was closed :-)

For your point about matching GCC, I do not know enough about either GCC without a thorough investigation to answer meaningfully.

All I know is that:

• -o binary is how the V handles generating its binary file.
• -keepc -o file.c is how V handles generating the C file from the V code.

I was surprised to see -o used that way: When I first used V, I initially expected -keepc file.c -o binary as UI. As it stands, the two options are mutually exclusive in a single command.

It may be that -c file.c -o binary could be a way, but this was not your question. I will let you decide what you feel is best for V. It is your language and compiler toolchain, not mine.

I was only wondering if -dump-c-flags used with -keepc should save the flags that could be used to compile the generated C file instead of the flags used to compile the tmp file.

If the file is moved after the code generation, then the compiler options point to a missing file and will not allow the user to modify the C file and compile using the settings as they are.

It seems counterintuitive, but again, I am only giving my opinion as a user, nothing more.

[medvednikov]

-o file.c works without -keepc

I'll investigate this and get back to you soon.