Merge pull request #1272 from 4144/gccwarnings

Add some new gcc 6 warnings and fix some error found by it

6 files changed, 209 insertions, 65 deletions

diff --git a/configure b/configure
index a29752859..bf832ba87 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in 8291fd8.
+# From configure.ac 045a895.
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.69.
 #
@@ -4603,6 +4603,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 # -Wunused-parameter -Wunused-but-set-parameter unused parameters
 # -Wunused-macros unused macro warnings, but it also enable unused parameters
 # -Wstrict-prototypes show warning in grammar.y
+# -wdiscarded-qualifiers show different const removal
 # attributes suggestion
 #  -Wsuggest-attribute=const -Wsuggest-attribute=format -Wsuggest-attribute=pure
 
@@ -6986,11 +6987,12 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 #AC_CHECK_COMPILER_WFLAG(cast-align)
+#AC_CHECK_COMPILER_WFLAG(logical-op) # some useless warnings
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wlogical-op" >&5
-$as_echo_n "checking whether $CC supports -Wlogical-op... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wnested-externs" >&5
+$as_echo_n "checking whether $CC supports -Wnested-externs... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Wlogical-op"
+		CFLAGS="$CFLAGS -Werror -Wnested-externs"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -6999,12 +7001,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Wlogical-op"
+				CFLAGS="$OLD_CFLAGS -Wnested-externs"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wlogical-op" >&5
-$as_echo_n "checking whether $CC can actually use -Wlogical-op... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Wlogical-op"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wnested-externs" >&5
+$as_echo_n "checking whether $CC can actually use -Wnested-externs... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wnested-externs"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7018,7 +7020,7 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Wlogical-op"
+							CFLAGS="$OLD_CFLAGS -Wnested-externs"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7036,10 +7038,10 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wnested-externs" >&5
-$as_echo_n "checking whether $CC supports -Wnested-externs... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wold-style-definition" >&5
+$as_echo_n "checking whether $CC supports -Wold-style-definition... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Wnested-externs"
+		CFLAGS="$CFLAGS -Werror -Wold-style-definition"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -7048,12 +7050,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Wnested-externs"
+				CFLAGS="$OLD_CFLAGS -Wold-style-definition"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wnested-externs" >&5
-$as_echo_n "checking whether $CC can actually use -Wnested-externs... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Wnested-externs"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wold-style-definition" >&5
+$as_echo_n "checking whether $CC can actually use -Wold-style-definition... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wold-style-definition"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7067,7 +7069,7 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Wnested-externs"
+							CFLAGS="$OLD_CFLAGS -Wold-style-definition"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7085,10 +7087,10 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wold-style-definition" >&5
-$as_echo_n "checking whether $CC supports -Wold-style-definition... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Woverlength-strings" >&5
+$as_echo_n "checking whether $CC supports -Woverlength-strings... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Wold-style-definition"
+		CFLAGS="$CFLAGS -Werror -Woverlength-strings"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -7097,12 +7099,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Wold-style-definition"
+				CFLAGS="$OLD_CFLAGS -Woverlength-strings"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wold-style-definition" >&5
-$as_echo_n "checking whether $CC can actually use -Wold-style-definition... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Wold-style-definition"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Woverlength-strings" >&5
+$as_echo_n "checking whether $CC can actually use -Woverlength-strings... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Woverlength-strings"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7116,7 +7118,7 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Wold-style-definition"
+							CFLAGS="$OLD_CFLAGS -Woverlength-strings"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7134,10 +7136,10 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Woverlength-strings" >&5
-$as_echo_n "checking whether $CC supports -Woverlength-strings... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wredundant-decls" >&5
+$as_echo_n "checking whether $CC supports -Wredundant-decls... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Woverlength-strings"
+		CFLAGS="$CFLAGS -Werror -Wredundant-decls"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -7146,12 +7148,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Woverlength-strings"
+				CFLAGS="$OLD_CFLAGS -Wredundant-decls"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Woverlength-strings" >&5
-$as_echo_n "checking whether $CC can actually use -Woverlength-strings... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Woverlength-strings"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wredundant-decls" >&5
+$as_echo_n "checking whether $CC can actually use -Wredundant-decls... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wredundant-decls"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7165,7 +7167,7 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Woverlength-strings"
+							CFLAGS="$OLD_CFLAGS -Wredundant-decls"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7183,10 +7185,10 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wredundant-decls" >&5
-$as_echo_n "checking whether $CC supports -Wredundant-decls... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wcast-qual" >&5
+$as_echo_n "checking whether $CC supports -Wcast-qual... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Wredundant-decls"
+		CFLAGS="$CFLAGS -Werror -Wcast-qual"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -7195,12 +7197,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Wredundant-decls"
+				CFLAGS="$OLD_CFLAGS -Wcast-qual"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wredundant-decls" >&5
-$as_echo_n "checking whether $CC can actually use -Wredundant-decls... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Wredundant-decls"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wcast-qual" >&5
+$as_echo_n "checking whether $CC can actually use -Wcast-qual... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wcast-qual"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7214,7 +7216,7 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Wredundant-decls"
+							CFLAGS="$OLD_CFLAGS -Wcast-qual"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7232,10 +7234,10 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wcast-qual" >&5
-$as_echo_n "checking whether $CC supports -Wcast-qual... " >&6; }
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wmisleading-indentation" >&5
+$as_echo_n "checking whether $CC supports -Wmisleading-indentation... " >&6; }
 		OLD_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS -Werror -Wcast-qual"
+		CFLAGS="$CFLAGS -Werror -Wmisleading-indentation"
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 int foo;
@@ -7244,12 +7246,12 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-				CFLAGS="$OLD_CFLAGS -Wcast-qual"
+				CFLAGS="$OLD_CFLAGS -Wmisleading-indentation"
 				# Optionally, run a test
 				if test "x" != "x"; then
-					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wcast-qual" >&5
-$as_echo_n "checking whether $CC can actually use -Wcast-qual... " >&6; }
-					CFLAGS="$OLD_CFLAGS -Werror -Wcast-qual"
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wmisleading-indentation" >&5
+$as_echo_n "checking whether $CC can actually use -Wmisleading-indentation... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wmisleading-indentation"
 					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -7263,7 +7265,56 @@ $as_echo "no" >&6; }
 
 							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-							CFLAGS="$OLD_CFLAGS -Wcast-qual"
+							CFLAGS="$OLD_CFLAGS -Wmisleading-indentation"
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+				fi
+
+else
+
+				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+				CFLAGS="$OLD_CFLAGS"
+
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wnull-dereference" >&5
+$as_echo_n "checking whether $CC supports -Wnull-dereference... " >&6; }
+		OLD_CFLAGS="$CFLAGS"
+		CFLAGS="$CFLAGS -Werror -Wnull-dereference"
+		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int foo;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+				CFLAGS="$OLD_CFLAGS -Wnull-dereference"
+				# Optionally, run a test
+				if test "x" != "x"; then
+					{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wnull-dereference" >&5
+$as_echo_n "checking whether $CC can actually use -Wnull-dereference... " >&6; }
+					CFLAGS="$OLD_CFLAGS -Werror -Wnull-dereference"
+					cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+							CFLAGS="$OLD_CFLAGS"
+
+
+							{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+							CFLAGS="$OLD_CFLAGS -Wnull-dereference"
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
@@ -7545,6 +7596,94 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
 
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wno-suggest-attribute=format" >&5
+$as_echo_n "checking whether $CC supports -Wno-suggest-attribute=format... " >&6; }
+		OLD_CFLAGS="$CFLAGS"
+		CFLAGS="$CFLAGS -Werror -Wno-suggest-attribute=format"
+		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int foo;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+				# Recent versions of gcc don't fail if -Wno-foo is not recognized
+				# (unless there are also other warnings), so we also check for -Wfoo
+				# which always fails if not supported
+				CFLAGS="$OLD_CFLAGS -Werror -Wsuggest-attribute=format"
+				cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int foo;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+						{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+						CFLAGS="$OLD_CFLAGS -Wno-suggest-attribute=format"
+						# Optionally, run a test
+						if test "x" != "x"; then
+							{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC can actually use -Wno-suggest-attribute=format" >&5
+$as_echo_n "checking whether $CC can actually use -Wno-suggest-attribute=format... " >&6; }
+							CFLAGS="$OLD_CFLAGS -Werror -Wsuggest-attribute=format"
+							cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+									{ $as_echo "$as_me:${as_lineno-$LINENO}: result: not needed but enabled" >&5
+$as_echo "not needed but enabled" >&6; }
+									CFLAGS="$OLD_CFLAGS"
+
+else
+
+									CFLAGS="$OLD_CFLAGS -Werror -Wno-suggest-attribute=format"
+									cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+											{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+											CFLAGS="$OLD_CFLAGS -Wno-suggest-attribute=format"
+
+else
+
+											{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+											CFLAGS="$OLD_CFLAGS"
+
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+						fi
+
+else
+
+						{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+						CFLAGS="$OLD_CFLAGS"
+
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+else
+
+				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+				CFLAGS="$OLD_CFLAGS"
+
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+
 # Certain versions of gcc make -Wshadow completely useless by making it flood
 # you with unnecessary warnings <https://lkml.org/lkml/2006/11/28/239>
 # Let's check if we can really use it
diff --git a/configure.in b/configure.ac
index 3968dc568..d6f783505 100644
--- a/configure.in
+++ b/configure.ac
@@ -492,6 +492,7 @@ AC_LANG([C])
 # -Wunused-parameter -Wunused-but-set-parameter unused parameters
 # -Wunused-macros unused macro warnings, but it also enable unused parameters
 # -Wstrict-prototypes show warning in grammar.y
+# -wdiscarded-qualifiers show different const removal
 # attributes suggestion
 #  -Wsuggest-attribute=const -Wsuggest-attribute=format -Wsuggest-attribute=pure
 
@@ -675,7 +676,7 @@ if test "$enable_lto" != "no" ; then
 	)
 fi
 
-AC_DEFUN(AC_CHECK_SANITIZER_FLAG,
+AC_DEFUN([AC_CHECK_SANITIZER_FLAG],
 	[
 		AC_MSG_CHECKING([whether $CC supports -fsanitize=$1])
 		OLD_CFLAGS="$CFLAGS"
@@ -741,7 +742,7 @@ if test "$enable_sanitize" != "no" ; then
 fi
 
 
-AC_DEFUN(AC_CHECK_COMPILER_WFLAG,
+AC_DEFUN([AC_CHECK_COMPILER_WFLAG],
 	[
 		AC_MSG_CHECKING([whether $CC supports -W$1])
 		OLD_CFLAGS="$CFLAGS"
@@ -776,7 +777,7 @@ AC_DEFUN(AC_CHECK_COMPILER_WFLAG,
 	]
 )
 
-AC_DEFUN(AC_CHECK_COMPILER_WNOFLAG,
+AC_DEFUN([AC_CHECK_COMPILER_WNOFLAG],
 	[
 		AC_MSG_CHECKING([whether $CC supports -Wno-$1])
 		OLD_CFLAGS="$CFLAGS"
@@ -854,15 +855,18 @@ AC_CHECK_COMPILER_WFLAG(missing-include-dirs)
 AC_CHECK_COMPILER_WFLAG(suggest-attribute=noreturn)
 AC_CHECK_COMPILER_WFLAG(undef)
 #AC_CHECK_COMPILER_WFLAG(cast-align)
-AC_CHECK_COMPILER_WFLAG(logical-op)
+#AC_CHECK_COMPILER_WFLAG(logical-op) # some useless warnings
 AC_CHECK_COMPILER_WFLAG(nested-externs)
 AC_CHECK_COMPILER_WFLAG(old-style-definition)
 AC_CHECK_COMPILER_WFLAG(overlength-strings)
 AC_CHECK_COMPILER_WFLAG(redundant-decls)
 AC_CHECK_COMPILER_WFLAG(cast-qual)
+AC_CHECK_COMPILER_WFLAG(misleading-indentation)
+AC_CHECK_COMPILER_WFLAG(null-dereference)
 AC_CHECK_COMPILER_WNOFLAG(format-nonliteral)
 AC_CHECK_COMPILER_WNOFLAG(switch)
 AC_CHECK_COMPILER_WNOFLAG(missing-field-initializers)
+AC_CHECK_COMPILER_WNOFLAG(suggest-attribute=format)
 
 # Certain versions of gcc make -Wshadow completely useless by making it flood
 # you with unnecessary warnings <https://lkml.org/lkml/2006/11/28/239>
diff --git a/src/map/clif.c b/src/map/clif.c
index 4ec58b6bc..1948eecea 100644
--- a/src/map/clif.c
+++ b/src/map/clif.c
@@ -9785,8 +9785,6 @@ void clif_parse_GlobalMessage(int fd, struct map_session_data *sd)
 	bool is_fakename = false;
 	int outlen = 0;
 
-	nullpo_retv(sd);
-
 	packet = RP2PTR(fd);
 	message = clif->process_chat_message(sd, packet, full_message, sizeof full_message);
 	if (message == NULL)
@@ -17801,7 +17799,6 @@ void clif_parse_bgqueue_checkstate(int fd, struct map_session_data *sd)
 {
 	const struct packet_bgqueue_checkstate *p = RP2PTR(fd);
 
-	nullpo_retv(sd);
 	if (sd->bg_queue.arena && sd->bg_queue.type) {
 		clif->bgqueue_update_info(sd,sd->bg_queue.arena->id,bg->id2pos(sd->bg_queue.arena->queue_id,sd->status.account_id));
 	} else {
diff --git a/src/map/script.c b/src/map/script.c
index e869ddb62..181ff350f 100644
--- a/src/map/script.c
+++ b/src/map/script.c
@@ -10085,6 +10085,7 @@ int buildin_killmonsterall_sub_strip(struct block_list *bl,va_list ap)
 	struct mob_data *md;
 
 	md = BL_CAST(BL_MOB, bl);
+	nullpo_ret(md);
 	if (md->npc_event[0])
 		md->npc_event[0] = 0;
 
diff --git a/src/map/skill.c b/src/map/skill.c
index d3cb8d0be..3004bf0e9 100644
--- a/src/map/skill.c
+++ b/src/map/skill.c
@@ -9280,7 +9280,7 @@ int skill_castend_nodamage_id(struct block_list *src, struct block_list *bl, uin
 				improv_skill_lv = 4 + skill_lv;
 				clif->skill_nodamage (src, bl, skill_id, skill_lv, 1);
 
-				if (sd == NULL) {
+				if (sd != NULL) {
 					sd->state.abra_flag = 2;
 					sd->skillitem = improv_skill_id;
 					sd->skillitemlv = improv_skill_lv;
diff --git a/src/map/status.c b/src/map/status.c
index a8771c0a5..39bb25737 100644
--- a/src/map/status.c
+++ b/src/map/status.c
@@ -5576,9 +5576,9 @@ unsigned short status_calc_speed(struct block_list *bl, struct status_change *sc
 		{
 			int val = 0;
 
-			if( sd && sc->data[SC_HIDING] && pc->checkskill(sd,RG_TUNNELDRIVE) > 0 )
+			if ( sd && sc->data[SC_HIDING] && pc->checkskill(sd,RG_TUNNELDRIVE) > 0 ) {
 				val = 120 - 6 * pc->checkskill(sd,RG_TUNNELDRIVE);
-			else
+			} else {
 				if( sd && sc->data[SC_CHASEWALK] && sc->data[SC_CHASEWALK]->val3 < 0 )
 					val = sc->data[SC_CHASEWALK]->val3;
 				else
@@ -5648,8 +5648,8 @@ unsigned short status_calc_speed(struct block_list *bl, struct status_change *sc
 					if( sd && sd->bonus.speed_rate + sd->bonus.speed_add_rate > 0 ) // permanent item-based speedup
 						val = max( val, sd->bonus.speed_rate + sd->bonus.speed_add_rate );
 				}
-
-				speed_rate += val;
+			}
+			speed_rate += val;
 		}
 
 		//GetMoveHasteValue1()
@@ -7495,8 +7495,9 @@ int status_change_start(struct block_list *src, struct block_list *bl, enum sc_t
 			if (tick == 1) return 1; //Minimal duration: Only strip without causing the SC
 			break;
 		case SC_NOEQUIPSHIELD:
-			if( val2 == 1 ) val2 = 0; //GX effect. Do not take shield off..
-			else
+			if (val2 == 1) {
+				val2 = 0; //GX effect. Do not take shield off..
+			} else {
 				if (sd && !(flag&SCFLAG_LOADED)) {
 					int i;
 					if(sd->bonus.unstripable_equip&EQP_SHIELD)
@@ -7506,8 +7507,10 @@ int status_change_start(struct block_list *src, struct block_list *bl, enum sc_t
 						return 0;
 					pc->unequipitem(sd, i, PCUNEQUIPITEM_RECALC|PCUNEQUIPITEM_FORCE);
 				}
-				if (tick == 1) return 1; //Minimal duration: Only strip without causing the SC
-				break;
+			}
+			if (tick == 1)
+				return 1; //Minimal duration: Only strip without causing the SC
+			break;
 		case SC_NOEQUIPARMOR:
 			if (sd && !(flag&SCFLAG_LOADED)) {
 				int i;