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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug preprocessor/96952] __builtin_thread_pointer support cannot be probed
Date: Tue, 29 Sep 2020 16:21:21 +0000	[thread overview]
Message-ID: <bug-96952-4-UIVupT1B4M@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-96952-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96952

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Eric Botcazou from comment #4)
> What about detecting the support at configure time and defining a macro
> during the compilation?  Everyone has been doing this for more that 3
> decades...

Sorry, but it doesn't work. How do you suggest libstdc++ should use
configure-time checks to find out what features are present in the compiler
including the libstdc++ headers later? I don't know what that compiler is at
configure time.

For example, installed libstdc++ headers might get included by the GCC release
that they belong to, or by unknown releases of Clang or ICC with different
feature sets and levels of standard conformance. Checking anything at configure
time is useless for code in headers.

  parent reply	other threads:[~2020-09-29 16:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-07 11:25 [Bug preprocessor/96952] New: " sorear at fastmail dot com
2020-09-07 11:32 ` [Bug preprocessor/96952] " fw at gcc dot gnu.org
2020-09-07 12:10 ` jakub at gcc dot gnu.org
2020-09-07 16:09 ` bugdal at aerifal dot cx
2020-09-29  7:19 ` ebotcazou at gcc dot gnu.org
2020-09-29 14:43 ` bugdal at aerifal dot cx
2020-09-29 15:24 ` ebotcazou at gcc dot gnu.org
2020-09-29 16:21 ` redi at gcc dot gnu.org [this message]
2020-09-29 19:06 ` ebotcazou at gcc dot gnu.org
2020-09-29 19:36 ` redi at gcc dot gnu.org
2023-08-15  0:58 ` [Bug c/96952] " hpa at zytor dot com

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