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[patch] Document handling of unrecognized -Wno- options
- From: Diego Novillo <dnovillo at google dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: gerald at pfeifer dot com, joseph at codesourcery dot com
- Date: Thu, 15 Apr 2010 12:50:12 -0400
- Subject: [patch] Document handling of unrecognized -Wno- options
This came up in an internal thread today. I've added the
following clarification.
OK for trunk and active branches?
Thanks. Diego.
* doc/invoke.texi: Explain how are unrecognized -Wno- warnings
handled.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ad8eff8..8b68315 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2807,6 +2807,15 @@ two forms, whichever is not the default. For further,
language-specific options also refer to @ref{C++ Dialect Options} and
@ref{Objective-C and Objective-C++ Dialect Options}.
+When an unrecognized warning label is requested (e.g.,
+@option{-Wunknown-warning}), GCC will emit a diagnostic stating
+that the option is not recognized. However, if the @samp{-Wno-} form
+is used, the behavior is slightly different: No diagnostic will be
+produced for @option{-Wno-unknown-warning} unless other diagnostics
+are being produced. This allows the use of new @option{-Wno-} options
+with old compilers, but if something goes wrong, the compiler will
+warn that an unrecognized option was used.
+
@table @gcctabopt
@item -pedantic
@opindex pedantic