diff options
Diffstat (limited to 'lib/autoconf/headers.m4')
| -rw-r--r-- | lib/autoconf/headers.m4 | 122 |
1 files changed, 28 insertions, 94 deletions
diff --git a/lib/autoconf/headers.m4 b/lib/autoconf/headers.m4 index 7f5dbce2..6afff7d7 100644 --- a/lib/autoconf/headers.m4 +++ b/lib/autoconf/headers.m4 @@ -46,99 +46,17 @@ # [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND], # [INCLUDES]) # --------------------------------------------------------- -# We are slowly moving to checking headers with the compiler instead -# of the preproc, so that we actually learn about the usability of a -# header instead of its mere presence. But since users are used to -# the old semantics, they check for headers in random order and -# without providing prerequisite headers. This macro implements the -# transition phase, and should be cleaned up latter to use compilation -# only. -# -# If INCLUDES is empty, then check both via the compiler and preproc. -# If the results are different, issue a warning, but keep the preproc -# result. -# -# If INCLUDES is `-', keep only the old semantics. -# -# If INCLUDES is specified and different from `-', then use the new -# semantics only. +# This used to check for headers using the preprocessor only, but we +# have now switched to running a full compilation, so that we learn +# about the usability of a header instead of its mere presence. +# The old behavior is still available by specifying `-' as the +# INCLUDES, but this triggers a deprecation warning. # # The m4_indir allows for fewer expansions of $@. AC_DEFUN([AC_CHECK_HEADER], -[m4_indir(m4_case([$4], - [], [[_AC_CHECK_HEADER_MONGREL]], - [-], [[_AC_CHECK_HEADER_PREPROC]], - [[_AC_CHECK_HEADER_COMPILE]]), $@) -])# AC_CHECK_HEADER - - -# _AC_CHECK_HEADER_MONGREL_BODY -# ----------------------------- -# Shell function body for _AC_CHECK_HEADER_MONGREL -m4_define([_AC_CHECK_HEADER_MONGREL_BODY], -[ AS_LINENO_PUSH([$[]1]) - AS_VAR_SET_IF([$[]3], - [AC_CACHE_CHECK([for $[]2], [$[]3], [])], - [# Is the header compilable? -AC_MSG_CHECKING([$[]2 usability]) -AC_COMPILE_IFELSE([AC_LANG_SOURCE([$[]4 -@%:@include <$[]2>])], - [ac_header_compiler=yes], - [ac_header_compiler=no]) -AC_MSG_RESULT([$ac_header_compiler]) - -# Is the header present? -AC_MSG_CHECKING([$[]2 presence]) -AC_PREPROC_IFELSE([AC_LANG_SOURCE([@%:@include <$[]2>])], - [ac_header_preproc=yes], - [ac_header_preproc=no]) -AC_MSG_RESULT([$ac_header_preproc]) - -# So? What about this header? -case $ac_header_compiler:$ac_header_preproc:$ac_[]_AC_LANG_ABBREV[]_preproc_warn_flag in #(( - yes:no: ) - AC_MSG_WARN([$[]2: accepted by the compiler, rejected by the preprocessor!]) - AC_MSG_WARN([$[]2: proceeding with the compiler's result]) - ;; - no:yes:* ) - AC_MSG_WARN([$[]2: present but cannot be compiled]) - AC_MSG_WARN([$[]2: check for missing prerequisite headers?]) - AC_MSG_WARN([$[]2: see the Autoconf documentation]) - AC_MSG_WARN([$[]2: section "Present But Cannot Be Compiled"]) - AC_MSG_WARN([$[]2: proceeding with the compiler's result]) -m4_ifset([AC_PACKAGE_BUGREPORT], -[m4_n([( AS_BOX([Report this to ]AC_PACKAGE_BUGREPORT) - ) | sed "s/^/$as_me: WARNING: /" >&2])])dnl - ;; -esac - AC_CACHE_CHECK([for $[]2], [$[]3], - [AS_VAR_SET([$[]3], [$ac_header_compiler])])]) - AS_LINENO_POP -])#_AC_CHECK_HEADER_MONGREL_BODY - -# _AC_CHECK_HEADER_MONGREL(HEADER-FILE, -# [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND], -# [INCLUDES = DEFAULT-INCLUDES]) -# ------------------------------------------------------------------ -# Check using both the compiler and the preprocessor. If they disagree, -# warn, and the preproc wins. -# -# This is not based on _AC_CHECK_HEADER_COMPILE and _AC_CHECK_HEADER_PREPROC -# because it obfuscate the code to try to factor everything, in particular -# because of the cache variables, and the `checking ...' messages. -AC_DEFUN([_AC_CHECK_HEADER_MONGREL], -[AC_REQUIRE_SHELL_FN([ac_fn_]_AC_LANG_ABBREV[_check_header_mongrel], - [AS_FUNCTION_DESCRIBE([ac_fn_]_AC_LANG_ABBREV[_check_header_mongrel], - [LINENO HEADER VAR INCLUDES], - [Tests whether HEADER exists, giving a warning if it cannot be compiled - using the include files in INCLUDES and setting the cache variable VAR - accordingly.])], - [$0_BODY])]dnl -[AS_VAR_PUSHDEF([ac_Header], [ac_cv_header_$1])]dnl -[ac_fn_[]_AC_LANG_ABBREV[]_check_header_mongrel ]dnl -["$LINENO" "$1" "ac_Header" "AS_ESCAPE([AC_INCLUDES_DEFAULT([$4])], [""])" -AS_VAR_IF([ac_Header], [yes], [$2], [$3]) -AS_VAR_POPDEF([ac_Header])])# _AC_CHECK_HEADER_MONGREL +[m4_indir(m4_if([$4], [-], + [[_AC_CHECK_HEADER_PREPROC]], + [[_AC_CHECK_HEADER_COMPILE]]), $@)]) # _AC_CHECK_HEADER_COMPILE_BODY @@ -154,6 +72,7 @@ m4_define([_AC_CHECK_HEADER_COMPILE_BODY], AS_LINENO_POP ])# _AC_CHECK_HEADER_COMPILE_BODY + # _AC_CHECK_HEADER_COMPILE(HEADER-FILE, # [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND], # [INCLUDES = DEFAULT-INCLUDES]) @@ -172,6 +91,7 @@ AC_DEFUN([_AC_CHECK_HEADER_COMPILE], AS_VAR_IF([ac_Header], [yes], [$2], [$3]) AS_VAR_POPDEF([ac_Header])])# _AC_CHECK_HEADER_COMPILE + # _AC_CHECK_HEADER_PREPROC_BODY # ----------------------------- # Shell function body for _AC_CHECK_HEADER_PREPROC. @@ -185,22 +105,28 @@ m4_define([_AC_CHECK_HEADER_PREPROC_BODY], ])# _AC_CHECK_HEADER_PREPROC_BODY - # _AC_CHECK_HEADER_PREPROC(HEADER-FILE, # [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND]) # -------------------------------------------------------------- # Check the preprocessor accepts HEADER-FILE. AC_DEFUN([_AC_CHECK_HEADER_PREPROC], +[AC_DIAGNOSE([obsolete], [Checking for headers with the preprocessor is +deprecated. Specify prerequisite code to AC_CHECK_HEADER +instead of using fourth argument `-'. (Many headers need +no prerequisites. If you truly need to test whether +something passes the preprocessor but not the compiler, +use AC_PREPROC_IFELSE.)])]dnl [AC_REQUIRE_SHELL_FN([ac_fn_]_AC_LANG_ABBREV[_check_header_preproc], [AS_FUNCTION_DESCRIBE([ac_fn_]_AC_LANG_ABBREV[_check_header_preproc], [LINENO HEADER VAR], - [Tests whether HEADER is present, setting the cache variable VAR accordingly.])], + [Tests whether HEADER exists and can be preprocessed (in isolation), + setting the cache variable VAR accordingly.])], [$0_BODY])]dnl [AS_VAR_PUSHDEF([ac_Header], [ac_cv_header_$1])]dnl [ac_fn_[]_AC_LANG_ABBREV[]_check_header_preproc "$LINENO" "$1" "ac_Header" AS_VAR_IF([ac_Header], [yes], [$2], [$3]) -AS_VAR_POPDEF([ac_Header])dnl -])# _AC_CHECK_HEADER_PREPROC +AS_VAR_POPDEF([ac_Header])])# _AC_CHECK_HEADER_PREPROC + # _AC_CHECK_HEADER_OLD(HEADER-FILE, [ACTION-IF-FOUND], # [ACTION-IF-NOT-FOUND]) @@ -222,6 +148,14 @@ AC_DEFUN([_AC_CHECK_HEADER_NEW], You should use AC_CHECK_HEADER with a fourth argument.])]dnl [_AC_CHECK_HEADER_COMPILE($@)]) +# _AC_CHECK_HEADER_MONGREL(HEADER-FILE, +# [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND]) +# ------------------------------------------------------------------ +# In case anyone used this undocumented macro. Map to the _PREPROC +# semantics to minimize the chance of breaking anything. +AU_DEFUN([_AC_CHECK_HEADER_MONGREL], + [AC_CHECK_HEADER([$1], [$2], [$3], [-])]) + # _AH_CHECK_HEADER(HEADER-FILE) # ----------------------------- |