Re: RFA: Add -frecord-gcc-switches command line switch

[Nick Clifton <nickc at redhat dot com>]

Hi Mark,

> I see one more thing that I want to clarify before approving the patch:
>
> +	    fputs ("\t.ascii \"", asm_out_file);
> +
> +	  varasm_print_gcc_option (name);
> +	  fputs ("\\0\"\n", asm_out_file);
>
> Can we use ASM_OUTPUT_ASCII here instead?

Well yes, but it is a bit of a pain.  (Lots of copying of strings into 
buffers so that they can be combined later on).

> It looks like that might
> handle the escaping, quoting, embedded NUL issues that you're dealing
> with here, and make elf_record_gcc_switches work on any ELF platforms
> that use something other than .ascii for strings.  It looks to me like
> something like this:
>
>   ASM_OUTPUT_ASCII (asm_out_file, name, strlen (name) + 1);
>
> would work.  (The +1 is so that we encode the trailing NUL.)

Which unfortunately does not work.  The NULs are still skipped by the 
implementation of ASM_OUTPUT_ASCII in config/elfos.h.  (It treats them 
as sub-string terminators and breaks up the output into multiple strings).

A revised patch, using ASM_OUTPUT_ASCII and ASM_OUTPUT_SKIP (to generate 
the NULs) is attached.  I decided to ditch the code that specially 
handles double quote characters inside command line options, since this 
is a very rare occurrence, and it would mean that I would have to write 
my own customized implementation of snprintf.  I can put this back in 
though, if you feel that it is important.

How to do you feel about this version ?

Cheers
  Nick

PS.  In case anyone is wondering the NUL characters are needed so that 
the string merging code in the linker will see separate strings for each 
command line option, not just one huge long option.  The newline 
characters are not strictly necessary, but they improve the output from 
running "strings -a" on an executable containing the command line 
information.