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From: Richard Harnden <richard.nospam@gmail.invalid>
Newsgroups: comp.lang.c
Subject: Re: No warning at implicit removal of const. Was: relearning C: why
 does an in-place change to a char* segfault?
Date: Fri, 2 Aug 2024 13:04:55 +0100
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On 02/08/2024 11:02, Keith Thompson wrote:
> candycanearter07 <candycanearter07@candycanearter07.nomail.afraid>
> writes:
>> David Brown <david.brown@hesbynett.no> wrote at 17:56 this Thursday (GMT):
> [...]
>>> gcc has the option "-Wwrite-strings" that makes string literals in C
>>> have "const char" array type, and thus give errors when you try to
>>> assign to a non-const char * pointer.  But the option has to be
>>> specified explicitly (it is not in -Wall) because it changes the meaning
>>> of the code and can cause compatibility issues with existing correct code.
>>
>> -Wwrite-strings is included in -Wpedantic.
> 
> No it isn't, nor is it included in -Wall -- and it wouldn't make sense
> to do so.
> 
> The -Wpedantic option is intended to produce all required diagnostics
> for the specified C standard.  -Wwrite-strings gives string literals the
> type `const char[LENGTH]`, which enables useful diagnostics but is
> *non-conforming*.
> 
> For example, this program:
> 
> ```
> #include <stdio.h>
> int main(void) {
>      char *s = "hello, world";
>      puts(s);
> }
> ```
> 
> is valid (no diagnostic required), since it doesn't actually write to
> the string literal object, but `-Wwrite-strings` causes gcc to warn
> about it (because making the pointer non-const creates the potential for
> an error).
> 

Is there any reason not to always write ...

static const char *s = "hello, world";

.... ?

You get all the warnings for free that way.