Use autoconf, not gcc version, to decide which warnings we have

This gives more accurate results under Clang, which can only help us
detect more warnings in more places.

Fixes bug 19216; bugfix on 0.2.0.1-alpha

1 files changed, 57 insertions, 118 deletions

diff --git a/configure.ac b/configure.ac
index abed17f096..f80cb47dac 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1656,59 +1656,12 @@ esac
 
 # Add some more warnings which we use in development but not in the
 # released versions.  (Some relevant gcc versions can't handle these.)
+#
+# Note that we have to do this near the end  of the autoconf process, or
+# else we may run into problems when these warnings hit on the testing C
+# programs that autoconf wants to build.
 if test "x$enable_gcc_warnings_advisory" != "xno"; then
 
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4)
-#error
-#endif])], have_gcc4=yes, have_gcc4=no)
-
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 2)
-#error
-#endif])], have_gcc42=yes, have_gcc42=no)
-
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 3)
-#error
-#endif])], have_gcc43=yes, have_gcc43=no)
-
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
-#error
-#endif])], have_gcc46=yes, have_gcc46=no)
-
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
-#error
-#endif])], have_gcc47=yes, have_gcc47=no)
-
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
-#error
-#endif])], have_gcc48=yes, have_gcc48=no)
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 9)
-#error
-#endif])], have_gcc49=yes, have_gcc49=no)
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 5)
-#error
-#endif])], have_gcc5=yes, have_gcc5=no)
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
-#if !defined(__GNUC__) || (__GNUC__ < 6)
-#error
-#endif])], have_gcc6=yes, have_gcc6=no)
-
-  save_CFLAGS="$CFLAGS"
-  CFLAGS="$CFLAGS -Wshorten-64-to-32"
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [])], have_shorten64_flag=yes,
-                    have_shorten64_flag=no)
-  CFLAGS="$save_CFLAGS"
-
   case "$host" in
     *-*-openbsd* | *-*-bitrig*)
       # Some OpenBSD versions (like 4.8) have -Wsystem-headers by default.
@@ -1718,79 +1671,67 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
       CFLAGS="$CFLAGS -Wno-system-headers" ;;
   esac
 
+
   CFLAGS="$CFLAGS -W -Wfloat-equal -Wundef -Wpointer-arith"
   CFLAGS="$CFLAGS -Wstrict-prototypes -Wmissing-prototypes -Wwrite-strings"
   CFLAGS="$CFLAGS -Wredundant-decls -Wchar-subscripts -Wcomment -Wformat=2"
-  CFLAGS="$CFLAGS -Wwrite-strings -Wmissing-declarations -Wredundant-decls"
+  CFLAGS="$CFLAGS -Wwrite-strings -Wmissing-declarations"
   CFLAGS="$CFLAGS -Wnested-externs -Wbad-function-cast -Wswitch-enum"
   CFLAGS="$CFLAGS -Waggregate-return -Wpacked -Wunused"
   CFLAGS="$CFLAGS -Wunused-parameter"
 
-  if test "x$have_gcc4" = "xyes"; then
-    # These warnings break gcc 3.3.5 and work on gcc 4.0.2
-    CFLAGS="$CFLAGS -Winit-self -Wmissing-field-initializers -Wold-style-definition"
-  fi
-
-  if test "x$have_gcc42" = "xyes"; then
-    # These warnings break gcc 4.0.2 and work on gcc 4.2
-    # XXXX020 See if any of these work with earlier versions.
-    CFLAGS="$CFLAGS -Waddress -Wmissing-noreturn"
-  fi
-
-  if test "x$have_gcc42" = "xyes" && test "x$have_gcc5" != "xyes"; then
-    CFLAGS="$CFLAGS -Wstrict-overflow=1"
-    # We used to use -Wstrict-overflow=5, but that breaks us heavily under 4.3.
-    # Save it for GCC 5 where they improved the testing.
-  fi
-
-  if test "x$have_gcc42" = "xyes" && test "x$have_clang" = "xno"; then
-    # These warnings break gcc 4.0.2 and clang, but work on gcc 4.2
-    CFLAGS="$CFLAGS -Wnormalized=id -Woverride-init"
-  fi
-
-  if test "x$have_gcc43" = "xyes"; then
-    # These warnings break gcc 4.2 and work on gcc 4.3
-    # XXXX020 See if any of these work with earlier versions.
-    CFLAGS="$CFLAGS -Wextra -Warray-bounds"
-  fi
-
-  if test "x$have_gcc46" = "xyes"; then
-    # This warning was added in gcc 4.3, but it appears to generate
-    # spurious warnings in gcc 4.4.  I don't know if it works in 4.5.
-    CFLAGS="$CFLAGS -Wlogical-op"
-    # and these should be just fine in gcc 4.6
-    CFLAGS="$CFLAGS -Wmissing-format-attribute -Wsuggest-attribute=noreturn -Wsync-nand -Wtrampolines -Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros"
-    CFLAGS="$CFLAGS -Wdouble-promotion"
-    CFLAGS="$CFLAGS -Woverlength-strings"
+  # GCC4.3 users once report trouble with -Wstrict-overflow=5.  GCC5 users
+  # have it work better.
+  # CFLAGS="$CFLAGS -Wstrict-overflow=1"
+
+  # This warning was added in gcc 4.3, but it appears to generate
+  # spurious warnings in gcc 4.4.  I don't know if it works in 4.5.
+  #CFLAGS="$CFLAGS -Wlogical-op"
+
+  m4_foreach_w([warning_flag], [
+     -Waddress
+     -Warray-bounds
+     -Wc99-c11-compat
+     -Wdate-time
+     -Wdouble-promotion
+     -Wduplicated-cond
+     -Wextra
+     -Wfloat-conversion
+     -Wignored-attributes
+     -Winit-self
+     -Wlogical-op
+     -Wmissing-field-initializers
+     -Wmissing-format-attribute
+     -Wmissing-noreturn
+     -Wnormalized=id
+     -Wnull-dereference
+     -Wold-style-definition
+     -Woverlength-strings
+     -Woverride-init
+     -Wshift-count-negative
+     -Wshift-count-overflow
+     -Wshift-negative-value
+     -Wshift-overflow=2
+     -Wshorten-64-to-32
+     -Wsizeof-array-argument
+     -Wstrict-overflow=2
+     -Wsuggest-attribute=format
+     -Wsuggest-attribute=noreturn
+     -Wswitch-bool
+     -Wsync-nand
+     -Wtrampolines
+     -Wunused-but-set-parameter
+     -Wunused-but-set-variable
+     -Wunused-const-variable=2
+     -Wunused-local-typedefs
+     -Wvariadic-macros
+  ], [ TOR_CHECK_CFLAGS([warning_flag]) ])
+
+  if test "$tor_cv_cflags__Wnull_dereference" = "yes"; then
+    AC_DEFINE([HAVE_CFLAG_WNULL_DEREFERENCE], 1, [True if we have -Wnull-dereference])
   fi
-
-  if test "x$have_gcc47" = "xyes"; then
-     CFLAGS="$CFLAGS -Wunused-local-typedefs"
-  fi
-
-  if test "x$have_gcc48" = "xyes"; then
-     CFLAGS="$CFLAGS -Wsuggest-attribute=format"
-  fi
-
-  if test "x$have_gcc49" = "xyes"; then
-     CFLAGS="$CFLAGS -Wdate-time"
-     CFLAGS="$CFLAGS -Wfloat-conversion"
-  fi
-
-  if test "x$have_gcc5" = "xyes"; then
-     CFLAGS="$CFLAGS -Wc99-c11-compat -Wshift-count-negative -Wshift-count-overflow -Wsizeof-array-argument -Wswitch-bool"
-    CFLAGS="$CFLAGS -Wstrict-overflow=2"
-  fi
-
- if test "x$have_gcc6" = "xyes"; then
-     CFLAGS="$CFLAGS -Wignored-attributes -Wshift-negative-value -Wshift-overflow=2"
-     CFLAGS="$CFLAGS -Wnull-dereference"
-     CFLAGS="$CFLAGS -Wduplicated-cond"
-     CFLAGS="$CFLAGS -Wunused-const-variable=2"
-  fi
-
-  if test "x$have_shorten64_flag" = "xyes"; then
-    CFLAGS="$CFLAGS -Wshorten-64-to-32"
+  if test "$tor_cv_cflags__Woverlength_strings" = "yes"; then
+    AC_DEFINE([HAVE_CFLAG_WOVERLENGTH_STRINGS], 1, [True if we have -Woverlength-strings])
   fi
 
   if test "x$enable_fatal_warnings" = "xyes"; then
@@ -1799,8 +1740,6 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
     CFLAGS="$CFLAGS -Werror"
   fi
 
-##This will break the world on some 64-bit architectures
-# CFLAGS="$CFLAGS -Winline"
 fi
 
 if test "$enable_coverage" = "yes" && test "$have_clang" = "no"; then