is -Wportability enabled by default?

[Bruno Haible]

Hi,

In GNU gettext, automake-1.9b, when invoked without arguments, gives me
the warning:

src/Makefile.am:38: compiling `envsubst.c' with per-target flags requires `AM_PR
OG_CC_C_O' in `configure.ac'

Looking at the source code, it appears to be a 'portability' warning.
But "automake --help" says:

"Warning categories include:
...
  `portability'   portability issues
  `syntax'        dubious syntactic constructs (default)
  `unsupported'   unsupported or incomplete features (default)
  `all'           all the warnings
...
"
which appears to say that -Wportability needs to be enabled explicitly?

Bruno