Re: [PATCH 0/1 v2] add PAGER_ENV to build

[Jeff King <peff@peff.net>]

On Mon, Aug 01, 2016 at 09:49:36PM +0000, Eric Wong wrote:

> Changes from v1:
> 
> * dropped stringify macro in favor for quoting in Makefile
>   (diff below)
>   I'm not sure I like this change, and might be inclined to
>   go in the opposite direction of using the stringify macro
>   more widely to simplify the Makefile; but that is a separate
>   topic.

I think that's a dangerous direction. Try this:

-- >8 --
cat >foo.c <<\EOF
#include <stdio.h>

#define stringify_(x) #x
#define stringify(x) stringify_(x)

int main(void)
{
	printf("%s", stringify(FOO));
	return 0;
}
EOF

while read -r input; do
	gcc -Wall -Werror -DFOO="$input" foo.c
	./a.out
done
-- 8< --

and then try input like:

  this has          a lot of spaces
  this has a \backslash

You should see:

  this has a lot of spaces
  this has aackslash

I'll grant that backslashes and runs of whitespace are not things we'd
expect to find in most of our build-time config, but it still seems like
a bad direction to go (and actually, I wouldn't be surprised if
backslashes do end up in some of our build-time variables on Windows).

-Peff