[libmicrohttpd] 07/12: Added autoconf macro for checking compiler parameters/flags

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karlson2k pushed a commit to branch master
in repository libmicrohttpd.

commit 82a26bfed203b84ccccd791575b9185df69fa014
Author: Evgeny Grin (Karlson2k) <k2k@narod.ru>
AuthorDate: Fri Apr 1 13:55:36 2022 +0300

    Added autoconf macro for checking compiler parameters/flags
---
 m4/mhd_check_cc_flag.m4 | 254 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 254 insertions(+)

diff --git a/m4/mhd_check_cc_flag.m4 b/m4/mhd_check_cc_flag.m4
new file mode 100644
index 00000000..e6ba38f6
--- /dev/null
+++ b/m4/mhd_check_cc_flag.m4
@@ -0,0 +1,254 @@
+# SYNOPSIS
+#
+#   MHD_CHECK_CC_FLAG([FLAG-TO-TEST], [VARIABLE-TO-PREPEND-CFLAGS],
+#                     [ACTION-IF-SUPPORTED], [ACTION-IF-NOT-SUPPORTED])
+#
+# DESCRIPTION
+#
+#   This macro checks whether the specific compiler flag is supported.
+#   The check is performing by prepending FLAG-TO-TEST to CFLAGS, then
+#   prepending value of VARIABLE-TO-PREPEND-CFLAGS (if any) to CFLAGS, and
+#   then performing compile and link test. If test succeed without warnings,
+#   then the flag is considered to be suppoted. Otherwise, if compile and link
+#   without test flag can be done without any warning, the flag is considered
+#   to be unsuppoted.
+#
+#   Example usage:
+#
+#     MHD_CHECK_CC_FLAG([-Wshadow], [additional_CFLAGS],
+#                       [additional_CFLAGS="${additional_CFLAGS} -Wshadow"])
+#
+#   Defined cache variable used in check so if any test will not work
+#   correctly on some platform, user may simply fix it by giving cache
+#   variable in configure parameters, for example:
+#
+#     ./configure mhd_cv_cc_fl_supp__wshadow=no
+#
+#   This simplify building from source on exotic platforms as patching
+#   of configure.ac is not required to change results of tests.
+#
+# LICENSE
+#
+#   Copyright (c) 2022 Karlson2k (Evgeny Grin) <k2k@narod.ru>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+AC_DEFUN([MHD_CHECK_CC_FLAG],[dnl
+  AC_PREREQ([2.64])dnl for AS_VAR_IF, m4_ifnblank
+  AC_LANG_ASSERT([C])dnl
+  AC_REQUIRE([AC_PROG_CC])dnl
+  m4_ifblank([$1], [m4_fatal([$0: First macro argument must not be empty])])dnl
+  m4_bmatch(m4_normalize([$1]), [\s],dnl
+            [m4_fatal([$0: First macro argument must not contain 
whitespaces])])dnl
+  m4_bmatch(_mhd_norm_expd([$2]), [\s],dnl
+            [m4_fatal([$0: Second macro argument must not contain 
whitespaces])])dnl
+  m4_bmatch([$1], [\$], [m4_fatal([$0: First macro argument must not contain 
'$'])])dnl
+  m4_bmatch([$2], [\$], [m4_fatal([$0: Second macro argument must not contain 
'$'])])dnl
+  AC_REQUIRE([MHD_FIND_CC_FLAG_WARNPARAMS])dnl sets 'mhd_CFLAGS_params_warn' 
variable
+  _MHD_CHECK_CC_FLAG_BODY([$1],[$2],[$3],[$4],[mhd_CFLAGS_params_warn])dnl
+])
+
+
+# SYNOPSIS
+#
+#   _MHD_CHECK_CC_FLAG_BODY([FLAG-TO-TEST], [VARIABLE-TO-PREPEND-CFLAGS],
+#                           [ACTION-IF-SUPPORTED], [ACTION-IF-NOT-SUPPORTED],
+#                           [VARIABLE-TO-ENABLE-WARNS])
+#
+AC_DEFUN([_MHD_CHECK_CC_FLAG_BODY],[dnl
+  AC_LANG_ASSERT([C])dnl
+  m4_ifblank([$1], [m4_fatal([$0: First macro argument must not be empty])])dnl
+  m4_bmatch(_mhd_norm_expd([$1]), [\s],dnl
+            [m4_fatal([$0: First macro argument must not contain 
whitespaces])])dnl
+  m4_bmatch(_mhd_norm_expd([$2]), [\s],dnl
+            [m4_fatal([$0: Second macro argument must not contain 
whitespaces])])dnl
+  m4_bmatch([$1], [\$], [m4_fatal([$0: First macro argument must not contain 
'$'])])dnl
+  m4_bmatch([$2], [\$], [m4_fatal([$0: Second macro argument must not contain 
'$'])])dnl
+  m4_ifblank([$5], [m4_fatal([$0: Fifth macro argument must not be empty])])dnl
+  m4_bmatch([$5], [\$], [m4_fatal([$0: Fifth macro argument must not contain 
'$'])])dnl
+  AS_VAR_PUSHDEF([cv_Var], 
[mhd_cv_cc_fl_supp_]m4_bpatsubst(m4_tolower(_mhd_norm_expd([$1])),[[^a-z0-9]],[_]))dnl
+  dnl
+  AC_CACHE_CHECK([whether $[]CC supports _mhd_norm_expd([$1]) flag], cv_Var,
+    [dnl
+      AS_VAR_PUSHDEF([save_CFLAGS_Var], [mhd_check_cc_flag_save_CFLAGS])dnl
+      AS_VAR_SET([save_CFLAGS_Var],["${CFLAGS}"])
+      m4_ifnblank([$2],[dnl
+        m4_if(_mhd_norm_expd([$2]),[CFLAGS],
+          [CFLAGS="${save_CFLAGS_Var} _mhd_norm_expd([$1]) 
$[]{_mhd_norm_expd([$5])}"],
+          [CFLAGS="$[]{_mhd_norm_expd([$2])} _mhd_norm_expd([$1]) 
${save_CFLAGS_Var} $[]{_mhd_norm_expd([$5])}"])
+      ],[dnl
+        CFLAGS="_mhd_norm_expd([$1]) $[]CFLAGS $[]{_mhd_norm_expd([$5])}"
+      ])dnl
+      mhd_check_cc_flag_save_c_werror_flag="$ac_c_werror_flag"
+      ac_c_werror_flag=yes
+      [#] Reuse the same source for all the checks here
+      AC_LANG_CONFTEST([AC_LANG_SOURCE([[
+int main(void)
+{
+  return 0;
+}
+      ]])])
+      AC_LINK_IFELSE([],
+        [AS_VAR_SET([cv_Var],["yes"])],
+        [ [#] Compile and link failed if test flag added
+          m4_ifnblank([$2],[dnl
+            m4_if(_mhd_norm_expd([$2]),[CFLAGS],
+              [CFLAGS="${save_CFLAGS_Var} $[]{_mhd_norm_expd([$5])}"],
+              [CFLAGS="$[]{_mhd_norm_expd([$2])} ${save_CFLAGS_Var} 
$[]{_mhd_norm_expd([$5])}"])
+          ],[dnl
+            CFLAGS="${save_CFLAGS_Var} $[]{_mhd_norm_expd([$5])}"
+            ])dnl
+          AC_LINK_IFELSE([],
+            [AS_VAR_SET([cv_Var],["no"])],
+            [ [#] Compile and link failed if test flag removed as well
+              m4_ifnblank([$2],[dnl
+                m4_if(_mhd_norm_expd([$2]),[CFLAGS],
+                  [CFLAGS="${save_CFLAGS_Var} _mhd_norm_expd([$1])"],
+                  [CFLAGS="$[]{_mhd_norm_expd([$2])} _mhd_norm_expd([$1]) 
${save_CFLAGS_Var}"])
+              ],[dnl
+                CFLAGS="_mhd_norm_expd([$1]) ${save_CFLAGS_Var}"
+              ])dnl
+              ac_c_werror_flag="$mhd_check_cc_flag_save_c_werror_flag"
+              AC_LINK_IFELSE([],
+                [AS_VAR_SET([cv_Var],["yes"])],
+                [AS_VAR_SET([cv_Var],["no"])],
+              )
+            ]
+          )
+        ]
+      )
+      ac_c_werror_flag="$mhd_check_cc_flag_save_c_werror_flag"
+      AS_VAR_SET([CFLAGS],["${save_CFLAGS_Var}"])
+      AS_UNSET(save_CFLAGS_Var)
+      AS_VAR_POPDEF([save_CFLAGS_Var])dnl
+    ]
+  )
+  m4_ifnblank([$3$4],[dnl
+    AS_VAR_IF([cv_Var], ["yes"], [$3], m4_default_nblank([$4]))
+    ])dnl
+  AS_VAR_POPDEF([cv_Var])dnl
+])
+
+
+#
+# SYNOPSIS
+#
+#   MHD_FIND_CC_FLAG_WARNPARAMS()
+#
+AC_DEFUN([MHD_FIND_CC_FLAG_WARNPARAMS],[dnl
+  AC_LANG_ASSERT([C])dnl
+  AC_REQUIRE([MHD_FIND_CC_FLAG_WWARN])dnl
+  mhd_CFLAGS_params_warn=''
+  _MHD_CHECK_CC_FLAG_BODY([-Wunused-command-line-argument],[],
+    [
+      AS_IF([test -z "$mhd_CFLAGS_params_warn"],
+        [mhd_CFLAGS_params_warn='-Wunused-command-line-argument'],
+        [mhd_CFLAGS_params_warn="$mhd_CFLAGS_params_warn 
-Wunused-command-line-argument"]
+      )
+    ],[],[mhd_cv_cc_flag_Wwarn]
+  )
+  _MHD_CHECK_CC_FLAG_BODY([-Wignored-optimization-argument],[],
+    [
+      AS_IF([test -z "$mhd_CFLAGS_params_warn"],
+        [mhd_CFLAGS_params_warn='-Wignored-optimization-argument'],
+        [mhd_CFLAGS_params_warn="$mhd_CFLAGS_params_warn 
-Wignored-optimization-argument"]
+      )
+    ],[],[mhd_cv_cc_flag_Wwarn]
+  )
+  _MHD_CHECK_CC_FLAG_BODY([-Winvalid-command-line-argument],[],
+    [
+      AS_IF([test -z "$mhd_CFLAGS_params_warn"],
+        [mhd_CFLAGS_params_warn='-Winvalid-command-line-argument'],
+        [mhd_CFLAGS_params_warn="$mhd_CFLAGS_params_warn 
-Winvalid-command-line-argument"]
+      )
+    ],[],[mhd_cv_cc_flag_Wwarn]
+  )
+  _MHD_CHECK_CC_FLAG_BODY([-Wunknown-argument],[],
+    [
+      AS_IF([test -z "$mhd_CFLAGS_params_warn"],
+        [mhd_CFLAGS_params_warn='-Wunknown-argument'],
+        [mhd_CFLAGS_params_warn="$mhd_CFLAGS_params_warn -Wunknown-argument"]
+      )
+    ],[],[mhd_cv_cc_flag_Wwarn]
+  )
+  AS_IF([test -z "$mhd_CFLAGS_params_warn"],
+    [mhd_CFLAGS_params_warn="$mhd_cv_cc_flag_Wwarn"],
+    [mhd_CFLAGS_params_warn="$mhd_cv_cc_flag_Wwarn $mhd_CFLAGS_params_warn"]
+  )
+])
+
+
+#
+# SYNOPSIS
+#
+#   MHD_FIND_CC_FLAG_WWARN()
+#
+AC_DEFUN([MHD_FIND_CC_FLAG_WWARN],[dnl
+  AC_PREREQ([2.64])dnl for AS_VAR_IF, m4_ifnblank
+  AC_REQUIRE([AC_PROG_CC])dnl
+  AC_LANG_ASSERT([C])dnl
+  AC_MSG_CHECKING([for $[]CC flag to warn on unknown -W parameters])
+  AC_CACHE_VAL([mhd_cv_cc_flag_Wwarn],
+    [
+      mhd_check_cc_flagwarn_save_c_werror_flag="$ac_c_werror_flag"
+      ac_c_werror_flag=yes
+      mhd_find_cc_Wwarn_save_CFLAGS="$CFLAGS"
+      AS_UNSET([mhd_cv_cc_flag_Wwarn])
+      for mhd_cv_cc_flag_Wwarn in '' '-Wunknown-warning-option' 
'-Werror=unknown-warning-option' ; do
+        AS_VAR_IF([mhd_cv_cc_flag_Wwarn], ["unknown"], [break])
+        [#] Reuse the same source for all the checks here
+        AC_LANG_CONFTEST([AC_LANG_SOURCE([[
+int main(void)
+{
+  return 0;
+}
+        ]])])
+        CFLAGS="-Wmhd-noexist-flag $mhd_find_cc_Wwarn_save_CFLAGS 
$mhd_cv_cc_flag_Wwarn"
+        AC_LINK_IFELSE([],
+          [],
+          [ [#] Compile and link failed if test flag and non-existing flag 
added
+            CFLAGS="$mhd_find_cc_Wwarn_save_CFLAGS $mhd_cv_cc_flag_Wwarn"
+            AC_LINK_IFELSE([],
+              [ [#] Compile and link succeed if only test flag added
+                break
+              ]
+            )
+          ]
+        )
+      done
+      CFLAGS="$mhd_find_cc_Wwarn_save_CFLAGS"
+      AS_VAR_IF([mhd_cv_cc_flag_Wwarn], ["unknown"],
+        [
+          _AS_ECHO_LOG([No suitable flags detected. Check whether default 
flags are correct.])
+          AC_LINK_IFELSE([AC_LANG_SOURCE([[
+int main(void)
+{
+  return 0;
+}
+            ]])],
+            [:],
+            [ [#] Compile and link fails (or warns) with default flags
+              AC_MSG_WARN([Compiler warns (of fails) with default flags!])
+              AC_MSG_WARN([Check whether compiler and compiler flags are 
correct.])
+            ]
+          )
+        ]
+      )
+      CFLAGS="$mhd_find_cc_Wwarn_save_CFLAGS"
+      AS_UNSET([mhd_find_cc_Wwarn_save_CFLAGS])
+      ac_c_werror_flag="$mhd_check_cc_flagwarn_save_c_werror_flag"
+      AS_UNSET([mhd_check_cc_flagwarn_save_c_werror_flag])
+    ]
+  )
+  AS_IF([test -z "$mhd_cv_cc_flag_Wwarn"],
+    [AC_MSG_RESULT([none needed])],
+    [AC_MSG_RESULT([$mhd_cv_cc_flag_Wwarn])])
+  AS_VAR_IF([mhd_cv_cc_flag_Wwarn], ["unknown"],
+    [AC_MSG_WARN([Unable to find compiler flags to warn on unsupported -W 
options. Final compiler options may be suboptimal.])])
+
+])

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