Hi Paul, > that incorrect line comes because ac_compile_for_check_decl is used > before it is set. And this occurs because Emacs's configure.ac's first > use of AC_CHECK_DECL is executed only on alpha platforms (which my > platform is not), which means the initialization of > ac_compile_for_check_decl is skipped.
The Emacs configure.ac is not written in a robust way. It contains 'case' and 'if'/'test' statements which conditionally execute the Autoconf macros AC_MSG_CHECKING AC_MSG_ERROR AC_MSG_WARN AC_MSG_RESULT AC_CACHE_CHECK AC_LINK_IFELSE AC_LANG_PROGRAM AC_PATH_PROG AC_CHECK_DECL AC_DEFINE AC_CHECK_HEADER AC_CHECK_PROG AC_CHECK_FUNCS AC_COMPILE_IFELSE AC_CHECK_LIB AC_TRY_LINK AC_PREPROC_IFELSE AC_CONFIG_FILES AC_MSG_NOTICE If any of these macros, in its implementation, performs an AC_REQUIRE, you may get a problem, as described in [1]. Do we have a statement in the Autoconf documentation that none of the built-in macros does an AC_REQUIRE? I don't think so. Therefore I would suggest that the particular 'case' and 'if'/'test' statements - or even the entire main body of the configure.ac, from line 130 to line 5588 - gets wrapped in an AC_DEFUN that gets invoked once. The other alternative is to state formally that none of these AC_* macros do an AC_REQUIRE. But then it's hard to find a proper place for the gl_COMPILER_PREPARE_CHECK_DECL invocation (without adding extra code to configure scripts that don't use AC_CHECK_DECL). What would you suggest? Bruno [1] https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Prerequisite-Macros.html
