From: Guy Harris <guy@alum.mit.edu>
Date: Tue, 7 May 2013 06:54:20 +0000 (-0700)
Subject: With .devel, use -W flags iff the compiler supports them.
X-Git-Tag: tcpdump-4.5.0~80^2~12
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/7d0510cec8de0f7157050e9daaf0246d7d6c7eeb

With .devel, use -W flags iff the compiler supports them.

Don't base the question of whether to use a particular -W flag on
whether we're compiling with GCC or not, and on which version of GCC
we're using; some compilers, such as clang, also support many of those
-W flags.  Base it on whether the compiler complains if we use it (which
means, for clang, that we have to force it to exit with a non-zero exit
status if it doesn't like a flag; otherwise, we'll specify it, and clang
will warn about it on every compile).
---

diff --git a/aclocal.m4 b/aclocal.m4
index 7573fae3..55e32103 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -202,6 +202,60 @@ AC_DEFUN(AC_LBL_C_INIT,
     fi
 ])
 
+dnl
+dnl Check whether, if you pass an unknown warning option to the
+dnl compiler, it fails or just prints a warning message and succeeds.
+dnl Set ac_lbl_unknown_warning_option_error to the appropriate flag
+dnl to force an error if it would otherwise just print a warning message
+dnl and succeed.
+dnl
+AC_DEFUN(AC_LBL_CHECK_UNKNOWN_WARNING_OPTION_ERROR,
+    [
+	AC_MSG_CHECKING([whether the compiler fails when given an unknown warning option])
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS -Wxyzzy-this-will-never-succeed-xyzzy"
+	AC_TRY_COMPILE(
+	    [],
+	    [return 0],
+	    [
+		AC_MSG_RESULT([no])
+		#
+		# We're assuming this is clang, where
+		# -Werror=unknown-warning-option is the appropriate
+		# option to force the compiler to fail.
+		# 
+		ac_lbl_unknown_warning_option_error="-Werror=unknown-warning-option"
+	    ],
+	    [
+		AC_MSG_RESULT([yes])
+	    ])
+	CFLAGS="$save_CFLAGS"
+    ])
+
+dnl
+dnl Check whether the compiler option specified as the second argument
+dnl is supported by the compiler and, if so, add it to the macro
+dnl specified as the first argument
+dnl
+AC_DEFUN(AC_LBL_CHECK_COMPILER_OPT,
+    [
+	AC_MSG_CHECKING([whether the compiler supports the $2 option])
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error $2"
+	AC_TRY_COMPILE(
+	    [],
+	    [return 0],
+	    [
+		AC_MSG_RESULT([yes])
+		CFLAGS="$save_CFLAGS"
+		$1="$$1 $2"
+	    ],
+	    [
+		AC_MSG_RESULT([no])
+		CFLAGS="$save_CFLAGS"
+	    ])
+    ])
+
 #
 # Try compiling a sample of the type of code that appears in
 # gencode.c with "inline", "__inline__", and "__inline".
@@ -792,11 +846,11 @@ EOF
     fi])
 
 dnl
-dnl If using gcc and the file .devel exists:
-dnl	Compile with -g (if supported) and -Wall
-dnl	If using gcc 2 or later, do extra prototype checking and some other
-dnl	checks
+dnl If the file .devel exists:
+dnl	Add some warning flags if the compiler supports them
 dnl	If an os prototype include exists, symlink os-proto.h to it
+dnl	If we're using gcc:
+dnl	    Compile with -g (if supported)
 dnl
 dnl usage:
 dnl
@@ -814,15 +868,18 @@ AC_DEFUN(AC_LBL_DEVEL,
 	    $1="$$1 ${LBL_CFLAGS}"
     fi
     if test -f .devel ; then
+	    AC_LBL_CHECK_UNKNOWN_WARNING_OPTION_ERROR()
+	    AC_LBL_CHECK_COMPILER_OPT($1, -Wall)
+	    AC_LBL_CHECK_COMPILER_OPT($1, -Wmissing-prototypes)
+	    AC_LBL_CHECK_COMPILER_OPT($1, -Wstrict-prototypes)
+	    AC_LBL_CHECK_COMPILER_OPT($1, -Wwrite-strings)
+	    AC_LBL_CHECK_COMPILER_OPT($1, -Wpointer-arith)
+	    AC_LBL_CHECK_COMPILER_OPT($1, -W)
 	    if test "$GCC" = yes ; then
 		    if test "${LBL_CFLAGS+set}" != set; then
 			    if test "$ac_cv_prog_cc_g" = yes ; then
 				    $1="-g $$1"
 			    fi
-			    $1="$$1 -Wall"
-			    if test $ac_cv_lbl_gcc_vers -gt 1 ; then
-				    $1="$$1 -Wmissing-prototypes -Wstrict-prototypes -Wwrite-strings -Wpointer-arith -W"
-			    fi
 		    fi
 	    else
 		    case "$host_os" in
diff --git a/configure b/configure
index 20ba1c14..f7b49d81 100755
--- a/configure
+++ b/configure
@@ -11289,15 +11289,407 @@ rm -f os-proto.h
 	    V_CCOPT="$V_CCOPT ${LBL_CFLAGS}"
     fi
     if test -f .devel ; then
+
+	{ echo "$as_me:$LINENO: checking whether the compiler fails when given an unknown warning option" >&5
+echo $ECHO_N "checking whether the compiler fails when given an unknown warning option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS -Wxyzzy-this-will-never-succeed-xyzzy"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		#
+		# We're assuming this is clang, where
+		# -Werror=unknown-warning-option is the appropriate
+		# option to force the compiler to fail.
+		#
+		ac_lbl_unknown_warning_option_error="-Werror=unknown-warning-option"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+	CFLAGS="$save_CFLAGS"
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wall option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wall option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wall"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wall"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wmissing-prototypes option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wmissing-prototypes option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wmissing-prototypes"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wmissing-prototypes"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wstrict-prototypes option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wstrict-prototypes option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wstrict-prototypes"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wstrict-prototypes"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wwrite-strings option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wwrite-strings option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wwrite-strings"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wwrite-strings"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wpointer-arith option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wpointer-arith option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wpointer-arith"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wpointer-arith"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -W option" >&5
+echo $ECHO_N "checking whether the compiler supports the -W option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -W"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -W"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
 	    if test "$GCC" = yes ; then
 		    if test "${LBL_CFLAGS+set}" != set; then
 			    if test "$ac_cv_prog_cc_g" = yes ; then
 				    V_CCOPT="-g $V_CCOPT"
 			    fi
-			    V_CCOPT="$V_CCOPT -Wall"
-			    if test $ac_cv_lbl_gcc_vers -gt 1 ; then
-				    V_CCOPT="$V_CCOPT -Wmissing-prototypes -Wstrict-prototypes -Wwrite-strings -Wpointer-arith -W"
-			    fi
 		    fi
 	    else
 		    case "$host_os" in