options.texi (EnabledBy): Document that the argument must be a Common option.

gcc/ChangeLog:

2015-08-09  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	* doc/options.texi (EnabledBy): Document that the argument must be
	a Common option.
	* doc/invoke.texi (Wnull-dereference): Move after Wnonnull.
	Not enabled by -Wall.
	* optc-gen.awk: Give nicer error messages. Detect if the argument
	of EnabledBy is not a Common option.
	* common.opt (Wnull-dereference): Not enabled by -Wall.
	* opt-functions.awk (lang_enabled_by): Nicer error messages.

gcc/c-family/ChangeLog:

2015-08-09  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	* c.opt (Wchkp): Use LangEnabledBy instead of EnabledBy.

From-SVN: r226751

gcc/ChangeLog

+2015-08-09  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	* doc/options.texi (EnabledBy): Document that the argument must be
+	a Common option.
+	* doc/invoke.texi (Wnull-dereference): Move after Wnonnull.
+	Not enabled by -Wall.
+	* optc-gen.awk: Give nicer error messages. Detect if the argument
+	of EnabledBy is not a Common option.
+	* common.opt (Wnull-dereference): Not enabled by -Wall.
+	* opt-functions.awk (lang_enabled_by): Nicer error messages.
+
 2015-08-09  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/driver-i386.c (host_detect_local_cpu): Treat

gcc/c-family/ChangeLog

+2015-08-09  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	* c.opt (Wchkp): Use LangEnabledBy instead of EnabledBy.
+
 2015-08-06  Andrew Sutton  <andrew.n.sutton@gmail.com>
 	    Braden Obrzut  <admin@maniacsvault.net>
 	    Jason Merrill  <jason@redhat.com>

gcc/c-family/c.opt

@@ -335,7 +335,7 @@ C ObjC C++ ObjC++ Var(warn_char_subscripts) Warning LangEnabledBy(C ObjC C++ Obj
 Warn about subscripts whose type is \"char\"
 
 Wchkp
-C ObjC C++ ObjC++ Var(warn_chkp) Warning EnabledBy(Wall)
+C ObjC C++ ObjC++ Var(warn_chkp) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 Warn about memory access errors found by Pointer Bounds Checker
 
 Wclobbered

gcc/common.opt

@@ -593,7 +593,7 @@ Common RejectNegative Joined UInteger Warning
 -Wlarger-than=<number>	Warn if an object is larger than <number> bytes
 
 Wnull-dereference
-Common Var(warn_null_dereference) Warning EnabledBy(Wall)
+Common Var(warn_null_dereference) Warning
 Warn if dereferencing a NULL pointer may lead to erroneous or undefined behavior
 
 Wunsafe-loop-optimizations

gcc/doc/invoke.texi

@@ -3722,6 +3722,15 @@ requiring a non-null value by the @code{nonnull} function attribute.
 @option{-Wnonnull} is included in @option{-Wall} and @option{-Wformat}.  It
 can be disabled with the @option{-Wno-nonnull} option.
 
+@item -Wnull-dereference
+@opindex Wnull-dereference
+@opindex Wno-null-dereference
+Warn if the compiler detects paths that trigger erroneous or
+undefined behavior due to dereferencing a null pointer.  This option
+is only active when @option{-fdelete-null-pointer-checks} is active,
+which is enabled by optimizations in most targets.  The precision of
+the warnings depends on the optimization options used.
+
 @item -Winit-self @r{(C, C++, Objective-C and Objective-C++ only)}
 @opindex Winit-self
 @opindex Wno-init-self
@@ -4158,16 +4167,6 @@ In order to get a warning about an unused function parameter, you must
 either specify @option{-Wextra -Wunused} (note that @option{-Wall} implies
 @option{-Wunused}), or separately specify @option{-Wunused-parameter}.
 
-@item -Wnull-dereference
-@opindex Wnull-dereference
-@opindex Wno-null-dereference
-Warn if the compiler detects paths that trigger erroneous or
-undefined behavior due to dereferencing a null pointer.  This option
-is only active when @option{-fdelete-null-pointer-checks} is active,
-which is enabled by optimizations in most targets.  The precision of
-the warnings depends on the optimization options used.  This option is
-enabled by @option{-Wall}.
-
 @item -Wuninitialized
 @opindex Wuninitialized
 @opindex Wno-uninitialized

gcc/doc/options.texi

@@ -464,7 +464,9 @@ value of @option{-fmath-errno} for languages that do not use
 If not explicitly set, the option is set to the value of
 @option{-@var{opt}}; multiple options can be given, separated by
 @code{||}.  The third form using @code{&&} specifies that the option is
-only set if both @var{opt} and @var{opt2} are set.
+only set if both @var{opt} and @var{opt2} are set. The options @var{opt}
+and @var{opt2} must have the @code{Common} property; otherwise, use
+@code{LangEnabledBy}.
 
 @item LangEnabledBy(@var{language}, @var{opt})
 @itemx LangEnabledBy(@var{language}, @var{opt}, @var{posarg}, @var{negarg})

gcc/opt-functions.awk

@@ -324,7 +324,7 @@ function lang_enabled_by(enabledby_langs, enabledby_name, enabledby_posarg, enab
     } else if (enabledby_posarg == "" && enabledby_negarg == "") {
         with_args = ""
     } else {
-        print "#error LangEnabledBy("enabledby_langs","enabledby_name", " \
+        print "#error " opts[i] " LangEnabledBy("enabledby_langs","enabledby_name", " \
             enabledby_posarg", " enabledby_negargs                  \
             ") with three arguments, it should have either 2 or 4"
     }
@@ -333,8 +333,8 @@ function lang_enabled_by(enabledby_langs, enabledby_name, enabledby_posarg, enab
     for (k = 1; k <= n_enabledby_array; k++) {
         enabledby_index = opt_numbers[enabledby_array[k]];
         if (enabledby_index == "") {
-             print "#error LangEnabledBy("enabledby_langs","enabledby_name", " \
-                 enabledby_posarg", " enabledby_negargs") has invalid ENABLEDBY_NAME"
+             print "#error " opts[i] " LangEnabledBy("enabledby_langs","enabledby_name", " \
+                 enabledby_posarg", " enabledby_negargs"), unknown option '" enabledby_name "'"
         } else {
             for (j = 1; j <= n_enabledby_arg_langs; j++) {
                  lang_name = lang_sanitized_name(enabledby_arg_langs[j]);

gcc/optc-gen.awk

@@ -30,7 +30,21 @@
 # Dump that array of options into a C file.
 END {
 
-# Record first EnabledBy and LangEnabledBy uses.
+
+# Combine the flags of identical switches.  Switches
+# appear many times if they are handled by many front
+# ends, for example.
+for (i = 0; i < n_opts; i++) {
+    merged_flags[i] = flags[i]
+}
+for (i = 0; i < n_opts; i++) {
+    while(i + 1 != n_opts && opts[i] == opts[i + 1] ) {
+	merged_flags[i + 1] = merged_flags[i] " " merged_flags[i + 1];
+	i++;
+    }
+}
+
+# Record EnabledBy and LangEnabledBy uses.
 n_enabledby = 0;
 for (i = 0; i < n_langs; i++) {
     n_enabledby_lang[i] = 0;
@@ -48,15 +62,19 @@ for (i = 0; i < n_opts; i++) {
         }
         n_enabledby_names = split(enabledby_arg, enabledby_names, split_sep);
         if (logical_and != 0 && n_enabledby_names > 2) {
-            print "#error EnabledBy (Wfoo && Wbar && Wbaz) not currently supported"
+            print "#error " opts[i] " EnabledBy(Wfoo && Wbar && Wbaz) currently not supported"
         }
         for (j = 1; j <= n_enabledby_names; j++) {
             enabledby_name = enabledby_names[j];
             enabledby_index = opt_numbers[enabledby_name];
             if (enabledby_index == "") {
-                print "#error Enabledby: " enabledby_name 
-            } else {
-                condition = "";
+                print "#error " opts[i] " Enabledby(" enabledby_name "), unknown option '" enabledby_name "'"
+            } else if (!flag_set_p("Common", merged_flags[enabledby_index])) {
+		print "#error " opts[i] " Enabledby(" enabledby_name "), '" \
+		    enabledby_name "' must have flag 'Common'"		\
+		    " to use Enabledby(), otherwise use LangEnabledBy()"
+	    } else {
+		condition = "";
                 if (logical_and != 0) {
                     opt_var_name_1 = search_var_name(enabledby_names[1], opt_numbers, opts, flags, n_opts);
                     opt_var_name_2 = search_var_name(enabledby_names[2], opt_numbers, opts, flags, n_opts);