Joseph S. Myers - Re: [PATCH] Add -Womitted-conditional-op warning (original) (raw)

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• From: "Joseph S. Myers"
• To: Andi Kleen
• Cc: gcc-patches at gcc dot gnu dot org
• Date: Fri, 2 Feb 2007 17:57:27 +0000 (UTC)
• Subject: Re: [PATCH] Add -Womitted-conditional-op warning
• References: <200702021802.59563.ak@suse.de>

On Fri, 2 Feb 2007, Andi Kleen wrote:

I implemented a warning for this case. I guess it's relatively obscure, but will not hurt. The warning is enabled by default, but can be disabled with -Wno-omitted-conditional-op.

This extension seems like one that could be used in macros in system headers and so maybe the warning should be disabled by extension (for C, see disable_extension_diagnostics / restore_extension_diagnostics).
Or do you think that the particular cases you warn for are never going to arise from macros (given those could be replaced by ... ? 1 : ...)?

+@item -Wno-omitted-conditional-op +@opindex Wno-omitted-conditional-op +Don't warn for dangerous uses of the +?: with omitted middle operand GNU extension. When the condition +in the ?: operator is a computed boolean the omitted value will +be always 1. Often the user expects it to be a value computed +inside the conditional expression instead. Gcc by default warns +for this, but this option disables it.

Two spaces after "." at end of sentence in Texinfo. "GCC" not "Gcc". Use @code or @samp around "?:". Include a cross-reference to the section of the manual documenting this extension.

-- Joseph S. Myers joseph@codesourcery.com

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