build-sys: turn some warnings into errors

Make the build sys error out on missing function prototypes, missing
variable declarations, implicit function declarations or forgotten return
statements.

None of these conditions are acceptable, and by making them hard errors, the
build bots can detect them earlier.

diff --git a/configure.ac b/configure.ac
index 571907593471ca66e92ec20ffc0b947e055d2170..b767175fa10cec1efc0231e108899d83411da87f 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -159,10 +159,12 @@ CC_CHECK_FLAGS_APPEND([with_cflags], [CFLAGS], [\
         -Wdeclaration-after-statement \
         -Wfloat-equal \
         -Wsuggest-attribute=noreturn \
-        -Wmissing-prototypes \
+        -Werror=missing-prototypes \
+        -Werror=implicit-function-declaration \
+        -Werror=missing-declarations \
+        -Werror=return-type \
         -Wstrict-prototypes \
         -Wredundant-decls \
-        -Wmissing-declarations \
         -Wmissing-noreturn \
         -Wshadow \
         -Wendif-labels \