From: Gerald Pfeifer <gerald@pfeifer.com>
To: David Malcolm <dmalcolm@redhat.com>, Martin Sebor <msebor@gmail.com>
Cc: Marek Polacek <polacek@redhat.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Joseph Myers <joseph@codesourcery.com>,
Martin Sebor <msebor@redhat.com>,
Jason Merrill <jason@redhat.com>
Subject: Re: C/C++ PATCH to implement -Wmultistatement-macros (PR c/80116)
Date: Fri, 09 Jun 2017 22:03:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.21.1706092358030.5843@anthias.pfeifer.com> (raw)
In-Reply-To: <322f3053-7021-980f-c918-6c4666d82f32@gmail.com>
On Thu, 8 Jun 2017, David Malcolm wrote:
> How about:
>
> "Warn about unsafe multiple statement macros that appear to be guarded
> by a clause such as if, else, while, or for, in which only the first
> statement is actually guarded after the macro is expanded."
>
> or somesuch?
Yes, I like this.
On Thu, 8 Jun 2017, Martin Sebor wrote:
> I don't have strong feelings about the current wording but if it
> should be tweaked for accuracy I would suggest to use the formal
> term "controlling expression", similarly to -Wswitch-unreachable.
That sounds good to me.
Some comments on the original patch:
+Warn about macros expanding to multiple statements in a body of a conditional,
+such as @code{if}, @code{else}, @code{for}, or @code{while}.
"in the body of a $WHATEVER_WE_SHALL_CALL_IT"
+The can usually be fixed by wrapping the macro in a do-while loop:
Is there a particular reason for not using an if(1) { } statement?
Ah, of course, a following else statement would be impacted by that.
Do we want to note that in the documentation?
+This warning is enabled by @option{-Wall} in C and C++.
"for C and C++" instead of "in"?
I'm curious to see how many issues this is going to find in real-world
code out there!
Gerald
next prev parent reply other threads:[~2017-06-09 22:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-08 16:49 Marek Polacek
2017-06-08 17:24 ` David Malcolm
2017-06-08 18:10 ` Martin Sebor
2017-06-09 22:03 ` Gerald Pfeifer [this message]
2017-06-13 13:46 ` Marek Polacek
2017-07-17 8:15 ` Gerald Pfeifer
2017-07-17 9:26 ` Marek Polacek
2017-06-13 10:05 ` Marek Polacek
2017-06-13 15:29 ` Joseph Myers
2017-06-19 10:01 ` Marek Polacek
2017-06-26 9:40 ` Marek Polacek
2017-06-26 13:13 ` David Malcolm
2017-06-10 0:47 ` Jason Merrill
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