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Re: format string is not a string literal
- From: Andrew Pinski <pinskia at gmail dot com>
- To: Simon Marchi <simon dot marchi at polymtl dot ca>
- Cc: Jack Howarth <howarth dot mailing dot lists at gmail dot com>, "Paul_Koning at dell dot com" <Paul_Koning at dell dot com>, "gdb at sourceware dot org" <gdb at sourceware dot org>
- Date: Wed, 25 Feb 2015 18:38:42 -0800
- Subject: Re: format string is not a string literal
- Authentication-results: sourceware.org; auth=none
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On Wed, Feb 25, 2015 at 6:35 PM, Andrew Pinski <firstname.lastname@example.org> wrote:
> On Wed, Feb 25, 2015 at 6:30 PM, Simon Marchi <email@example.com> wrote:
>>>> On Feb 25, 2015, at 4:41 PM, Jack Howarth <firstname.lastname@example.org> wrote:
>>>> See the additional comments from the llvm.org clang developers at...
>>> Then put this warning under a different flag. Anyways clang is broken and gdb should not change due to a broken compiler.
>> I would not say that clang is broken or that the warning is unclear.
>> The flag is -Wformat-nonliteral and the warning message is "format
>> string is not a string literal". I don't know how you can be more
>> clear and direct about the fact that the format string is not a string
>> literal. Looking at the code, we observe that clang is right (the
>> format string is indeed not a string literal). With the proper
>> function attributes, the compiler could do better checks and prevent
>> programming mistakes. Since clang pointed out this low-hanging fruit
>> improvement to gdb's code, why shouldn't we take advantage of it?
>> Anyway, Jack, you are welcome to submit a patch for this if you feel
>> like it and/or file a bug if it is not already done.
> Except GCC documents this options differently than clang implements:
> -Wformat-nonliteralIf -Wformat is specified, also warn if the format
> string is not a string literal and so cannot be checked, unless the
> format function takes its format arguments as a va_list.
> Notice the last part of the documentation.
> So this again is clang implements a GCC option but does not follow the
> documentation of GCC.
> How does clang document this option?
GCC has always documented this option this way since at least 3.1.1:
And there is no user documentation for clang for this option so clang is broken.