Re: missing warning about absence of AM_PROG_CC_C_O

[Bruno Haible]

Hello Ralf,

> missing AM_PROG_CC_C_O has been turned into a portability warning
> in 1.10.  -Wportability should be on by default in 1.10 and newer unless
> you use the 'foreign' option.  You should thus see it as soon as you add
> -Wportability to AUTOMAKE_OPTIONS in gltests/Makefile.am.
> ...
> The fact that the warning is output for gllib/Makefile.am is due to that
> one not using 'foreign' strictness, thus -Wportability is not turned
> off.

That explains it, indeed. I'm glad it's not a bug in automake.

Actually, the reason why I did not think of it as a warning, but as an
error, is because it's an error in 1.9.6 and the diagnostic did not change
much between 1.9.6 and 1.10:

In 1.9.6:

  $ automake --add-missing --copy
  gllib/Makefile.am: C objects in subdir but `AM_PROG_CC_C_O' not in 
`configure.ac'
  $ echo $?
  1

In 1.11:

  $ automake --add-missing --copy
  gllib/Makefile.am:33: compiling `uniwidth/width.c' in subdir requires 
`AM_PROG_CC_C_O' in `configure.ac'
  $ echo $?
  0

How about prefixing every diagnostic with "warning:" or "error:", like gcc
does it?

  foo.c:1:9: warning: integer constant is too large for its type
  foo.c:2:7: error: too many decimal points in number

Bruno