Re: [patch] Clarify interaction of -Wnarrowing with -std

[Gerald Pfeifer <gerald at pfeifer dot com>]

Hi Jonathan,

On Tue, 23 Feb 2016, Jonathan Wakely wrote:
> On 19/02/16 13:17 -0700, Sandra Loosemore wrote:
> > I suppose the patch is OK as it stands, but I was going to suggest
> > restructuring it so that it talks about the default behavior first and what
> > it does with non-default -std= options after that, instead of vice-versa.
> > Unfortunately I am backlogged on other things right now and it might take me
> > a day or two before I have time to come up with some alternate wording.  If
> > we are in a rush, go ahead and commit the existing patch meanwhile, I guess.
> Is this better?

I believe your follow-up patch did not get committed, nor did I
see any response from anyone.

To me it looks fine.  Did you hold of intentionally, or did this
get lost for lack of responses?

Sandra, what do you think?

Gerald

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 490df93..8d56efa 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2753,10 +2753,17 @@ During the link-time optimization warn about type mismatches in
 global declarations from different compilation units.
 Requires @option{-flto} to be enabled.  Enabled by default.
 
-@item -Wnarrowing @r{(C++ and Objective-C++ only)}
+@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
 @opindex Wnarrowing
 @opindex Wno-narrowing
-With @option{-std=gnu++98} or @option{-std=c++98}, warn when a narrowing
+For C++11 and later standards, narrowing conversions are diagnosed by default,
+as required by the standard.  A narrowing conversion from a constant produces
+an error, and a narrowing conversion from a non-constant produces a warning,
+but @option{-Wno-narrowing} suppresses the diagnostic.
+Note that this does not affect the meaning of well-formed code;
+narrowing conversions are still considered ill-formed in SFINAE contexts.
+
+With @option{-Wnarrowing} in C++98, warn when a narrowing
 conversion prohibited by C++11 occurs within
 @samp{@{ @}}, e.g.
 
@@ -2766,14 +2773,6 @@ int i = @{ 2.2 @}; // error: narrowing from double to int
 
 This flag is included in @option{-Wall} and @option{-Wc++11-compat}.
 
-When a later standard is in effect, e.g. when using @option{-std=c++11},
-narrowing conversions are diagnosed by default, as required by the standard.
-A narrowing conversion from a constant produces an error,
-and a narrowing conversion from a non-constant produces a warning,
-but @option{-Wno-narrowing} suppresses the diagnostic.
-Note that this does not affect the meaning of well-formed code;
-narrowing conversions are still considered ill-formed in SFINAE contexts.
-
 @item -Wnoexcept @r{(C++ and Objective-C++ only)}
 @opindex Wnoexcept
 @opindex Wno-noexcept