Bug 711895 - Tweak the warning options used for GCC builds (3rd attempt). r=waldo,derf,khuey,mhommey.

--HG--
extra : rebase_source : 20540c9b838ee3be6cb0847c1b90fdc3bd44059d

build/autoconf/compiler-opts.m4

@@ -82,3 +82,49 @@ if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -n "$MOZ_DEBUG_FLAGS"; then
 fi
 
 ])
+
+dnl GCC and clang will fail if given an unknown warning option like -Wfoobar. 
+dnl But later versions won't fail if given an unknown negated warning option
+dnl like -Wno-foobar.  So when we are check for support of negated warning 
+dnl options, we actually test the positive form, but add the negated form to 
+dnl the flags variable.
+
+AC_DEFUN([MOZ_C_SUPPORTS_WARNING],
+[
+    AC_CACHE_CHECK(whether the C compiler supports $1$2, $3,
+        [
+            AC_LANG_SAVE
+            AC_LANG_C
+            _SAVE_CFLAGS="$CFLAGS"
+            CFLAGS="$CFLAGS -Werror -W$2"
+            AC_TRY_COMPILE([],
+                           [return(0);],
+                           $3="yes",
+                           $3="no")
+            CFLAGS="$_SAVE_CFLAGS"
+            AC_LANG_RESTORE
+        ])
+    if test "${$3}" = "yes"; then
+        _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} $1$2"
+    fi
+])
+
+AC_DEFUN([MOZ_CXX_SUPPORTS_WARNING],
+[
+    AC_CACHE_CHECK(whether the C++ compiler supports $1$2, $3,
+        [
+            AC_LANG_SAVE
+            AC_LANG_CPLUSPLUS
+            _SAVE_CXXFLAGS="$CXXFLAGS"
+            CXXFLAGS="$CXXFLAGS -Werror -W$2"
+            AC_TRY_COMPILE([],
+                           [return(0);],
+                           $3="yes",
+                           $3="no")
+            CXXFLAGS="$_SAVE_CXXFLAGS"
+            AC_LANG_RESTORE
+        ])
+    if test "${$3}" = "yes"; then
+        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} $1$2"
+    fi
+])

configure.in

@@ -1707,15 +1707,27 @@ if test "$GNU_CC"; then
     _MOZ_RTTI_FLAGS_ON=-frtti
     _MOZ_RTTI_FLAGS_OFF=-fno-rtti
 
-    # Turn on GNU specific features
-    # -Wall - turn on all warnings
-    # -pedantic - make compiler warn about non-ANSI stuff, and
-    #             be a little bit stricter
+    # Turn on GNU-specific warnings:
+    # -Wall - turn on a lot of warnings
+    # -pedantic - this is turned on below
+    # -Wpointer-arith - enabled with -pedantic, but good to have even if not
     # -Wdeclaration-after-statement - MSVC doesn't like these
-    # Warnings slamm took out for now (these were giving more noise than help):
-    # -Wbad-function-cast - warns when casting a function to a new return type
-    # -Wshadow - removed because it generates more noise than help --pete
-    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -W -Wno-unused -Wpointer-arith -Wdeclaration-after-statement"
+    # -Werror=return-type - catches missing returns, zero false positives
+    # -Wtype-limits - catches overflow bugs, few false positives
+    # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
+    #
+    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -Wpointer-arith -Wdeclaration-after-statement"
+    MOZ_C_SUPPORTS_WARNING(-W, error=return-type, ac_c_has_werror_return_type)
+    MOZ_C_SUPPORTS_WARNING(-W, type-limits, ac_c_has_wtype_limits)
+    MOZ_C_SUPPORTS_WARNING(-W, empty-body, ac_c_has_wempty_body)
+    
+    # Turn off the following warnings that -Wall/-pedantic turn on:
+    # -Wno-unused - lots of violations in third-party code
+    # -Wno-overlength-strings - we exceed the minimum maximum length frequently
+    #
+    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wno-unused"
+    MOZ_C_SUPPORTS_WARNING(-Wno-, overlength-strings, ac_c_has_wno_overlength_strings)
+
     if test -z "$INTEL_CC" -a -z "$CLANG_CC"; then
        # Don't use -Wcast-align with ICC or clang
        case "$CPU_ARCH" in
@@ -1731,12 +1743,9 @@ if test "$GNU_CC"; then
     dnl Turn pedantic on but disable the warnings for long long
     _PEDANTIC=1
 
-    if test -z "$INTEL_CC"; then
-      _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -W"
-    fi
-
     _DEFINES_CFLAGS='-include $(DEPTH)/mozilla-config.h -DMOZILLA_CLIENT'
     _USE_CPP_INCLUDE_FLAG=1
+
 elif test "$SOLARIS_SUNPRO_CC"; then
     DSO_CFLAGS=''
     if test "$CPU_ARCH" = "sparc"; then
@@ -1764,8 +1773,32 @@ fi
 if test "$GNU_CXX"; then
     # FIXME: Let us build with strict aliasing. bug 414641.
     CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-strict-aliasing"
-    # Turn on GNU specific features
-    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual -Wsynth -Wno-ctor-dtor-privacy -Wno-non-virtual-dtor"
+
+    # Turn on GNU-specific warnings:
+    # -Wall - turn on a lot of warnings
+    # -pedantic - this is turned on below
+    # -Wpointer-arith - enabled with -pedantic, but good to have even if not
+    # -Woverloaded-virtual - ???
+    # -Werror=return-type - catches missing returns, zero false positives
+    # -Wtype-limits - catches overflow bugs, few false positives
+    # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
+    #
+    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual"
+    MOZ_CXX_SUPPORTS_WARNING(-W, error=return-type, ac_cxx_has_werror_return_type)
+    MOZ_CXX_SUPPORTS_WARNING(-W, type-limits, ac_cxx_has_wtype_limits)
+    MOZ_CXX_SUPPORTS_WARNING(-W, empty-body, ac_cxx_has_wempty_body)
+
+    # Turn off the following warnings that -Wall/-pedantic turn on:
+    # -Wno-ctor-dtor-privacy - ???
+    # -Wno-overlength-strings - we exceed the minimum maximum length frequently 
+    # -Wno-invalid-offsetof - we use offsetof on non-POD types frequently
+    # -Wno-variadic-macros - ???
+    #
+    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-ctor-dtor-privacy"
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, overlength-strings, ac_cxx_has_wno_overlength_strings)
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, invalid-offsetof, ac_cxx_has_wno_invalid_offsetof)
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, variadic-macros, ac_cxx_has_wno_variadic_macros)
+
     if test -z "$INTEL_CXX" -a -z "$CLANG_CXX"; then
        # Don't use -Wcast-align with ICC or clang
        case "$CPU_ARCH" in
@@ -1789,81 +1822,7 @@ if test "$GNU_CXX"; then
     # deleted function syntax.
     if test "$CLANG_CXX"; then
         _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-c++0x-extensions"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-extended-offsetof,
-                   ac_has_wno_extended_offsetof,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-extended-offsetof"
-            AC_TRY_COMPILE([$configure_static_assert_macros
-                            #ifndef __has_warning
-                            #define __has_warning(x) 0
-                            #endif],
-                           [CONFIGURE_STATIC_ASSERT(__has_warning("-Wextended-offsetof"))],
-                           ac_has_wno_extended_offsetof="yes",
-                           ac_has_wno_extended_offsetof="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_extended_offsetof" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-extended-offsetof"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-invalid-offsetof,
-                   ac_has_wno_invalid_offsetof,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-invalid-offsetof"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_wno_invalid_offsetof="yes",
-                           ac_has_wno_invalid_offsetof="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_invalid_offsetof" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-invalid-offsetof"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-variadic-macros,
-                   ac_has_wno_variadic_macros,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-variadic-macros"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_wno_variadic_macros="yes",
-                           ac_has_wno_variadic_macros="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_variadic_macros" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-variadic-macros"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Werror=return-type,
-                   ac_has_werror_return_type,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Werror=return-type"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_werror_return_type="yes",
-                           ac_has_werror_return_type="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_werror_return_type" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Werror=return-type"
+        MOZ_CXX_SUPPORTS_WARNING(-Wno-, extended-offsetof, ac_cxx_has_wno_extended_offsetof)
     fi
 
 else

content/smil/nsSMILAnimationFunction.cpp

@@ -671,7 +671,7 @@ nsSMILAnimationFunction::ScaleSimpleProgress(double aProgress,
     return aProgress;
 
   PRUint32 i = 0;
-  for (; i < numTimes - 2 && aProgress >= mKeyTimes[i+1]; ++i);
+  for (; i < numTimes - 2 && aProgress >= mKeyTimes[i+1]; ++i) { }
 
   if (aCalcMode == CALC_DISCRETE) {
     // discrete calcMode behaviour differs in that each keyTime defines the time

content/smil/nsSMILTimedElement.cpp

@@ -1767,7 +1767,7 @@ nsSMILTimedElement::GetNextGreater(const InstanceTimeList& aList,
 {
   nsSMILInstanceTime* result = nsnull;
   while ((result = GetNextGreaterOrEqual(aList, aBase, aPosition)) &&
-         result->Time() == aBase);
+         result->Time() == aBase) { }
   return result;
 }
 

content/xslt/src/base/txExpandedNameMap.h

@@ -102,8 +102,7 @@ protected:
 
         const txExpandedName key()
         {
-            NS_ASSERTION(mCurrentPos >= 0 &&
-                         mCurrentPos < mMap.mItems.Length(),
+            NS_ASSERTION(mCurrentPos < mMap.mItems.Length(),
                          "invalid position in txExpandedNameMap::iterator");
             return txExpandedName(mMap.mItems[mCurrentPos].mNamespaceID,
                                   mMap.mItems[mCurrentPos].mLocalName);
@@ -112,8 +111,7 @@ protected:
     protected:
         void* itemValue()
         {
-            NS_ASSERTION(mCurrentPos >= 0 &&
-                         mCurrentPos < mMap.mItems.Length(),
+            NS_ASSERTION(mCurrentPos < mMap.mItems.Length(),
                          "invalid position in txExpandedNameMap::iterator");
             return mMap.mItems[mCurrentPos].mValue;
         }

gfx/thebes/gfxFont.h

@@ -2336,19 +2336,19 @@ public:
     }
 
     bool CharIsSpace(PRUint32 aPos) {
-        NS_ASSERTION(0 <= aPos && aPos < mCharacterCount, "aPos out of range");
+        NS_ASSERTION(aPos < mCharacterCount, "aPos out of range");
         return mCharacterGlyphs[aPos].CharIsSpace();
     }
     bool CharIsTab(PRUint32 aPos) {
-        NS_ASSERTION(0 <= aPos && aPos < mCharacterCount, "aPos out of range");
+        NS_ASSERTION(aPos < mCharacterCount, "aPos out of range");
         return mCharacterGlyphs[aPos].CharIsTab();
     }
     bool CharIsNewline(PRUint32 aPos) {
-        NS_ASSERTION(0 <= aPos && aPos < mCharacterCount, "aPos out of range");
+        NS_ASSERTION(aPos < mCharacterCount, "aPos out of range");
         return mCharacterGlyphs[aPos].CharIsNewline();
     }
     bool CharIsLowSurrogate(PRUint32 aPos) {
-        NS_ASSERTION(0 <= aPos && aPos < mCharacterCount, "aPos out of range");
+        NS_ASSERTION(aPos < mCharacterCount, "aPos out of range");
         return mCharacterGlyphs[aPos].CharIsLowSurrogate();
     }
 

gfx/ycbcr/QuellGccWarnings.patch

@@ -0,0 +1,40 @@
+diff --git a/gfx/ycbcr/yuv_convert.cpp b/gfx/ycbcr/yuv_convert.cpp
+--- a/gfx/ycbcr/yuv_convert.cpp
++++ b/gfx/ycbcr/yuv_convert.cpp
+@@ -337,16 +337,17 @@ NS_GFX_(void) ScaleYCbCrToRGB32(const ui
+                                          source_dx_uv >> kFractionBits);
+         }
+       }
+       else {
+         ScaleYUVToRGB32Row_C(y_ptr, u_ptr, v_ptr,
+                              dest_pixel, width, source_dx);
+       }
+ #else
++      (void)source_dx_uv;
+       ScaleYUVToRGB32Row(y_ptr, u_ptr, v_ptr,
+                          dest_pixel, width, source_dx);
+ #endif
+     }
+   }
+   // MMX used for FastConvertYUVToRGB32Row and FilterRows requires emms.
+   if (has_mmx)
+     EMMS();
+diff --git a/gfx/ycbcr/yuv_row.h b/gfx/ycbcr/yuv_row.h
+--- a/gfx/ycbcr/yuv_row.h
++++ b/gfx/ycbcr/yuv_row.h
+@@ -129,14 +129,14 @@ extern SIMD_ALIGNED(int16 kCoefficientsR
+ #if defined(ARCH_CPU_X86) && !defined(ARCH_CPU_X86_64)
+ #if defined(_MSC_VER)
+ #define EMMS() __asm emms
+ #pragma warning(disable: 4799)
+ #else
+ #define EMMS() asm("emms")
+ #endif
+ #else
+-#define EMMS()
++#define EMMS() ((void)0)
+ #endif
+ 
+ }  // extern "C"
+ 
+ #endif  // MEDIA_BASE_YUV_ROW_H_

gfx/ycbcr/README

@@ -25,3 +25,5 @@ convert.patch contains the following changes:
 win64.patch: SSE2 optimization for Microsoft Visual C++ x64 version
 
 TypeFromSize.patch: Bug 656185 - Add a method to detect YUVType from plane sizes.
+
+QuellGccWarnings.patch: Bug 711895 - Avoid some GCC compilation warnings.

gfx/ycbcr/update.sh

@@ -9,3 +9,4 @@ cp $1/media/base/yuv_row_posix.cc yuv_row_c.cpp
 patch -p3 <convert.patch
 patch -p3 <win64.patch
 patch -p3 <TypeFromSize.patch
+patch -p3 <QuellGccWarnings.patch

gfx/ycbcr/yuv_convert.cpp

@@ -342,6 +342,7 @@ NS_GFX_(void) ScaleYCbCrToRGB32(const uint8* y_buf,
                              dest_pixel, width, source_dx);
       }
 #else
+      (void)source_dx_uv;
       ScaleYUVToRGB32Row(y_ptr, u_ptr, v_ptr,
                          dest_pixel, width, source_dx);
 #endif

gfx/ycbcr/yuv_row.h

@@ -134,7 +134,7 @@ extern SIMD_ALIGNED(int16 kCoefficientsRgbY[768][4]);
 #define EMMS() asm("emms")
 #endif
 #else
-#define EMMS()
+#define EMMS() ((void)0)
 #endif
 
 }  // extern "C"

js/jsd/jsd.h

@@ -379,10 +379,6 @@ jsd_GetErrorReporter(JSDContext*        jsdc,
                      JSD_ErrorReporter* reporter,
                      void**             callerdata);
 
-static JSBool
-jsd_DebugErrorHook(JSContext *cx, const char *message,
-                   JSErrorReport *report, void *closure);
-
 /***************************************************************************/
 /* Script functions */
 

js/jsd/jsd_high.c

@@ -276,6 +276,10 @@ jsd_DebuggerPause(JSDContext* jsdc, JSBool forceAllHooksOff)
     JS_SetDebugErrorHook(jsdc->jsrt, NULL, NULL);
 }
 
+static JSBool
+jsd_DebugErrorHook(JSContext *cx, const char *message,
+                   JSErrorReport *report, void *closure);
+
 void
 jsd_DebuggerUnpause(JSDContext* jsdc)
 {

js/src/build/autoconf/compiler-opts.m4

@@ -82,3 +82,49 @@ if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -n "$MOZ_DEBUG_FLAGS"; then
 fi
 
 ])
+
+dnl GCC and clang will fail if given an unknown warning option like -Wfoobar. 
+dnl But later versions won't fail if given an unknown negated warning option
+dnl like -Wno-foobar.  So when we are check for support of negated warning 
+dnl options, we actually test the positive form, but add the negated form to 
+dnl the flags variable.
+
+AC_DEFUN([MOZ_C_SUPPORTS_WARNING],
+[
+    AC_CACHE_CHECK(whether the C compiler supports $1$2, $3,
+        [
+            AC_LANG_SAVE
+            AC_LANG_C
+            _SAVE_CFLAGS="$CFLAGS"
+            CFLAGS="$CFLAGS -Werror -W$2"
+            AC_TRY_COMPILE([],
+                           [return(0);],
+                           $3="yes",
+                           $3="no")
+            CFLAGS="$_SAVE_CFLAGS"
+            AC_LANG_RESTORE
+        ])
+    if test "${$3}" = "yes"; then
+        _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} $1$2"
+    fi
+])
+
+AC_DEFUN([MOZ_CXX_SUPPORTS_WARNING],
+[
+    AC_CACHE_CHECK(whether the C++ compiler supports $1$2, $3,
+        [
+            AC_LANG_SAVE
+            AC_LANG_CPLUSPLUS
+            _SAVE_CXXFLAGS="$CXXFLAGS"
+            CXXFLAGS="$CXXFLAGS -Werror -W$2"
+            AC_TRY_COMPILE([],
+                           [return(0);],
+                           $3="yes",
+                           $3="no")
+            CXXFLAGS="$_SAVE_CXXFLAGS"
+            AC_LANG_RESTORE
+        ])
+    if test "${$3}" = "yes"; then
+        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} $1$2"
+    fi
+])

js/src/configure.in

@@ -1627,14 +1627,27 @@ if test "$GNU_CC"; then
     _MOZ_RTTI_FLAGS_ON=-frtti
     _MOZ_RTTI_FLAGS_OFF=-fno-rtti
 
-    # Turn on GNU specific features
-    # -Wall - turn on all warnings
-    # -pedantic - make compiler warn about non-ANSI stuff, and
-    #             be a little bit stricter
-    # Warnings slamm took out for now (these were giving more noise than help):
-    # -Wbad-function-cast - warns when casting a function to a new return type
-    # -Wshadow - removed because it generates more noise than help --pete
-    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -W -Wno-unused -Wpointer-arith"
+    # Turn on GNU-specific warnings:
+    # -Wall - turn on a lot of warnings
+    # -pedantic - this is turned on below
+    # -Wpointer-arith - enabled with -pedantic, but good to have even if not
+    # -Wdeclaration-after-statement - MSVC doesn't like these
+    # -Werror=return-type - catches missing returns, zero false positives
+    # -Wtype-limits - catches overflow bugs, few false positives
+    # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
+    #
+    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -Wpointer-arith -Wdeclaration-after-statement"
+    MOZ_C_SUPPORTS_WARNING(-W, error=return-type, ac_c_has_werror_return_type)
+    MOZ_C_SUPPORTS_WARNING(-W, type-limits, ac_c_has_wtype_limits)
+    MOZ_C_SUPPORTS_WARNING(-W, empty-body, ac_c_has_wempty_body)
+    
+    # Turn off the following warnings that -Wall/-pedantic turn on:
+    # -Wno-unused - lots of violations in third-party code
+    # -Wno-overlength-strings - we exceed the minimum maximum length frequently
+    #
+    _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wno-unused"
+    MOZ_C_SUPPORTS_WARNING(-Wno-, overlength-strings, ac_c_has_wno_overlength_strings)
+
     if test -z "$INTEL_CC" -a -z "$CLANG_CC"; then
        # Don't use -Wcast-align with ICC or clang
        case "$CPU_ARCH" in
@@ -1650,12 +1663,9 @@ if test "$GNU_CC"; then
     dnl Turn pedantic on but disable the warnings for long long
     _PEDANTIC=1
 
-    if test -z "$INTEL_CC"; then
-      _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -W"
-    fi
-
     _DEFINES_CFLAGS='-include $(DEPTH)/js-confdefs.h -DMOZILLA_CLIENT'
     _USE_CPP_INCLUDE_FLAG=1
+
 elif test "$SOLARIS_SUNPRO_CC"; then
     DSO_CFLAGS=''
     if test "$CPU_ARCH" = "sparc"; then
@@ -1681,8 +1691,31 @@ else
 fi
 
 if test "$GNU_CXX"; then
-    # Turn on GNU specific features
-    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual -Wsynth -Wno-ctor-dtor-privacy -Wno-non-virtual-dtor"
+    # Turn on GNU-specific warnings:
+    # -Wall - turn on a lot of warnings
+    # -pedantic - this is turned on below
+    # -Wpointer-arith - enabled with -pedantic, but good to have even if not
+    # -Woverloaded-virtual - ???
+    # -Werror=return-type - catches missing returns, zero false positives
+    # -Wtype-limits - catches overflow bugs, few false positives
+    # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
+    #
+    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual"
+    MOZ_CXX_SUPPORTS_WARNING(-W, error=return-type, ac_cxx_has_werror_return_type)
+    MOZ_CXX_SUPPORTS_WARNING(-W, type-limits, ac_cxx_has_wtype_limits)
+    MOZ_CXX_SUPPORTS_WARNING(-W, empty-body, ac_cxx_has_wempty_body)
+
+    # Turn off the following warnings that -Wall/-pedantic turn on:
+    # -Wno-ctor-dtor-privacy - ???
+    # -Wno-overlength-strings - we exceed the minimum maximum length frequently
+    # -Wno-invalid-offsetof - we use offsetof on non-POD types frequently
+    # -Wno-variadic-macros - ???
+    #
+    _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-ctor-dtor-privacy"
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, overlength-strings, ac_cxx_has_wno_overlength_strings)
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, invalid-offsetof, ac_cxx_has_wno_invalid_offsetof)
+    MOZ_CXX_SUPPORTS_WARNING(-Wno-, variadic-macros, ac_cxx_has_wno_variadic_macros)
+
     if test -z "$INTEL_CXX" -a -z "$CLANG_CXX"; then
        # Don't use -Wcast-align with ICC or clang
        case "$CPU_ARCH" in
@@ -1706,81 +1739,7 @@ if test "$GNU_CXX"; then
     # deleted function syntax.
     if test "$CLANG_CXX"; then
         _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-c++0x-extensions"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-extended-offsetof,
-                   ac_has_wno_extended_offsetof,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-extended-offsetof"
-            AC_TRY_COMPILE([$configure_static_assert_macros
-                            #ifndef __has_warning
-                            #define __has_warning(x) 0
-                            #endif],
-                           [CONFIGURE_STATIC_ASSERT(__has_warning("-Wextended-offsetof"))],
-                           ac_has_wno_extended_offsetof="yes",
-                           ac_has_wno_extended_offsetof="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_extended_offsetof" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-extended-offsetof"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-invalid-offsetof,
-                   ac_has_wno_invalid_offsetof,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-invalid-offsetof"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_wno_invalid_offsetof="yes",
-                           ac_has_wno_invalid_offsetof="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_invalid_offsetof" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-invalid-offsetof"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Wno-variadic-macros,
-                   ac_has_wno_variadic_macros,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Wno-variadic-macros"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_wno_variadic_macros="yes",
-                           ac_has_wno_variadic_macros="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_wno_variadic_macros" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wno-variadic-macros"
-    fi
-
-    AC_CACHE_CHECK(whether the compiler supports -Werror=return-type,
-                   ac_has_werror_return_type,
-        [
-            AC_LANG_SAVE
-            AC_LANG_CPLUSPLUS
-            _SAVE_CXXFLAGS="$CXXFLAGS"
-            CXXFLAGS="$CXXFLAGS -Werror=return-type"
-            AC_TRY_COMPILE([],
-                           [return(0);],
-                           ac_has_werror_return_type="yes",
-                           ac_has_werror_return_type="no")
-            CXXFLAGS="$_SAVE_CXXFLAGS"
-            AC_LANG_RESTORE
-        ])
-    if test "$ac_has_werror_return_type" = "yes"; then
-        _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Werror=return-type"
+        MOZ_CXX_SUPPORTS_WARNING(-Wno-, extended-offsetof, ac_cxx_has_wno_extended_offsetof)
     fi
 
 else

js/src/jsarray.cpp

@@ -404,11 +404,24 @@ DoGetElement(JSContext *cx, JSObject *obj, uint32_t index, JSBool *hole, Value *
     return true;
 }
 
+template<typename IndexType>
+static void
+AssertGreaterThanZero(IndexType index)
+{
+    JS_ASSERT(index >= 0);
+}
+
+template<>
+void
+AssertGreaterThanZero(uint32_t index)
+{
+}
+
 template<typename IndexType>
 static JSBool
 GetElement(JSContext *cx, JSObject *obj, IndexType index, JSBool *hole, Value *vp)
 {
-    JS_ASSERT(index >= 0);
+    AssertGreaterThanZero(index);
     if (obj->isDenseArray() && index < obj->getDenseArrayInitializedLength() &&
         !(*vp = obj->getDenseArrayElement(uint32_t(index))).isMagic(JS_ARRAY_HOLE)) {
         *hole = JS_FALSE;

js/src/jsgc.cpp

@@ -1367,7 +1367,7 @@ void
 JSCompartment::reduceGCTriggerBytes(size_t amount)
 {
     JS_ASSERT(amount > 0);
-    JS_ASSERT(gcTriggerBytes - amount >= 0);
+    JS_ASSERT(gcTriggerBytes >= amount);
     if (gcTriggerBytes - amount < GC_ALLOCATION_THRESHOLD * GC_HEAP_GROWTH_FACTOR)
         return;
     gcTriggerBytes -= amount;

js/src/jstypedarray.cpp

@@ -1775,9 +1775,7 @@ class TypedArrayTemplate
     {
         JS_ASSERT(tarray);
 
-        JS_ASSERT(0 <= begin);
         JS_ASSERT(begin <= getLength(tarray));
-        JS_ASSERT(0 <= end);
         JS_ASSERT(end <= getLength(tarray));
 
         JSObject *bufobj = getBuffer(tarray);

layout/generic/nsHTMLReflowMetrics.h

@@ -71,11 +71,11 @@ private:
   nsRect mRects[2];
 public:
   nsRect& Overflow(size_t aIndex) {
-    NS_ASSERTION(0 <= aIndex && aIndex < 2, "index out of range");
+    NS_ASSERTION(aIndex < 2, "index out of range");
     return mRects[aIndex];
   }
   const nsRect& Overflow(size_t aIndex) const {
-    NS_ASSERTION(0 <= aIndex && aIndex < 2, "index out of range");
+    NS_ASSERTION(aIndex < 2, "index out of range");
     return mRects[aIndex];
   }
 

other-licenses/android/linker.c

@@ -1925,6 +1925,7 @@ static unsigned int plt_reloc(soinfo *si, unsigned int num)
       return *(unsigned int *)(si->base + si->plt_rela[num].r_offset);
     }
 #endif
+    return 0;   // NOT REACHED
 }
 
 /* As this function is only referenced from assembly, we need to tell the