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From: David Malcolm
To: Joseph Myers ,
gcc-patches@gcc.gnu.org
Cc: David Malcolm
Subject: [PATCH] wwwdocs: gcc-15: start adding notes on C23
Date: Mon, 9 Dec 2024 14:44:42 -0500
Message-ID: <20241209194442.3154998-1-dmalcolm@redhat.com>
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How does this look?
Thanks
Dave
---
htdocs/gcc-15/changes.html | 12 ++++++++++++
htdocs/gcc-15/porting_to.html | 34 +++++++++++++++++++++++++++++++++-
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/htdocs/gcc-15/changes.html b/htdocs/gcc-15/changes.html
index 23866bde..94731f55 100644
--- a/htdocs/gcc-15/changes.html
+++ b/htdocs/gcc-15/changes.html
@@ -96,6 +96,18 @@ a work-in-progress.
musttail
statement attribute was added to enforce tail calls.
+C
+
+ - GCC 15 changes the default language version for C compilation from
+ -std=gnu17
+ to
+ -std=gnu23.
+ If your code relies on older versions of the C standard, you will need to
+ either add
+ -std=
+ to your build flags, or port your code; see the porting notes.
+
+
C++
diff --git a/htdocs/gcc-15/porting_to.html b/htdocs/gcc-15/porting_to.html
index 702cf507..2c9dce68 100644
--- a/htdocs/gcc-15/porting_to.html
+++ b/htdocs/gcc-15/porting_to.html
@@ -27,7 +27,39 @@ and provide solutions. Let us know if you have suggestions for improvements!
Note: GCC 15 has not been released yet, so this document is
a work-in-progress.
-
+C language issues
+
+C23 by default
+
+
+GCC 15 changes the default language version for C compilation from
+-std=gnu17
+to
+-std=gnu23.
+
+If your code relies on older versions of the C standard, you will need to
+either add -std=
+to your build flags, or port your code.
+
+C23 brings the following changes:
+
+Function prototypes with empty params change from implicit int
to void
+
+ In C23 ()
in a function declaration means the same as (void)
, whereas previously it implicitly declared the function to take an int
parameter.
+
+Hence
+
+extern int foo();
+
+now means
+
+extern int foo(void);
+
+rather than
+
+extern int foo(int);
+
+
Code relying on an implicit int
param declaration can be fixed for C23 by adding an explicit int
to the function prototype, or you can use -std= to select an earlier version of the C standard.
C++ language issues