common.opt: Add -Wattribute-warning.

         * common.opt: Add -Wattribute-warning.
         * doc/invoke.texi: Add documentation for -Wno-attribute-warning.
         * expr.c (expand_expr_real_1): Add new attribute to warning_at
         call to allow user configure behavior of "warning" attribute.

         * gcc.dg/Wno-attribute-warning.c: New test.

From-SVN: r265891

gcc/ChangeLog

+2018-11-17  Nikolai Merinov <n.merinov@inango-systems.com>
+
+         * common.opt: Add -Wattribute-warning.
+         * doc/invoke.texi: Add documentation for -Wno-attribute-warning.
+         * expr.c (expand_expr_real_1): Add new attribute to warning_at
+         call to allow user configure behavior of "warning" attribute.
+
 2018-11-07  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* target.def: Put @: after every vs., e.g., and i.e. where it is

gcc/common.opt

@@ -571,6 +571,10 @@ Wcpp
 Common Var(warn_cpp) Init(1) Warning
 Warn when a #warning directive is encountered.
 
+Wattribute-warning
+Common Var(warn_attribute_warning) Init(1) Warning
+Warn about uses of __attribute__((warning)) declarations.
+
 Wdeprecated-declarations
 Common Var(warn_deprecated_decl) Init(1) Warning
 Warn about uses of __attribute__((deprecated)) declarations.

gcc/doc/invoke.texi

@@ -292,6 +292,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wclobbered  -Wcomment  -Wconditionally-supported @gol
 -Wconversion  -Wcoverage-mismatch  -Wno-cpp  -Wdangling-else  -Wdate-time @gol
 -Wdelete-incomplete @gol
+-Wno-attribute-warning @gol
 -Wno-deprecated  -Wno-deprecated-declarations  -Wno-designated-init @gol
 -Wdisabled-optimization @gol
 -Wno-discarded-qualifiers  -Wno-discarded-array-qualifiers @gol
@@ -6978,6 +6979,15 @@ confused with the digit 0, and so is not the default, but may be
 useful as a local coding convention if the programming environment 
 cannot be fixed to display these characters distinctly.
 
+@item -Wno-attribute-warning
+@opindex Wno-attribute-warning
+@opindex Wattribute-warning
+Do not warn about usage of functions (@pxref{Function Attributes})
+declared with @code{warning} attribute.  By default, this warning is
+enabled.  @option{-Wno-attribute-warning} can be used to disable the
+warning or @option{-Wno-error=attribute-warning} can be used to
+disable the error when compiled with @option{-Werror} flag.
+
 @item -Wno-deprecated
 @opindex Wno-deprecated
 @opindex Wdeprecated

gcc/expr.c

@@ -10930,7 +10930,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 					 DECL_ATTRIBUTES (fndecl))) != NULL)
 	  {
 	    const char *ident = lang_hooks.decl_printable_name (fndecl, 1);
-	    warning_at (tree_nonartificial_location (exp), 0,
+	    warning_at (tree_nonartificial_location (exp),
+			OPT_Wattribute_warning,
 			"%Kcall to %qs declared with attribute warning: %s",
 			exp, identifier_to_locale (ident),
 			TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr))));

gcc/testsuite/ChangeLog

+2018-11-17  Nikolai Merinov <n.merinov@inango-systems.com>
+
+         * gcc.dg/Wno-attribute-warning.c: New test.
+
 2018-11-07  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/87904

gcc/testsuite/gcc.dg/Wno-attribute-warning.c

+/* { dg-do compile } */
+/* { dg-options "-Werror -Wno-error=attribute-warning" } */
+
+int f1(void) __attribute__ ((warning("Please avoid f1")));
+int func1(void)
+{
+  return f1(); /* { dg-warning "'f1' declared with attribute warning: Please avoid f1" } */
+}