[Python-checkins] cpython (merge 3.5 -> default): Issue #24324: merge from 3.5

[ned.deily]

https://hg.python.org/cpython/rev/8fecf6e17616
changeset:   100448:8fecf6e17616
parent:      100445:0d77a17567a4
parent:      100447:61f8f7610a88
user:        Ned Deily <nad at python.org>
date:        Tue Mar 08 00:40:12 2016 -0500
summary:
  Issue #24324: merge from 3.5

files:
  Misc/NEWS    |   4 ++++
  aclocal.m4   |   4 ++--
  configure    |  23 ++++++++++++++++-------
  configure.ac |  13 +++++++++++--
  4 files changed, 33 insertions(+), 11 deletions(-)


diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -811,6 +811,10 @@
 
 - Issue #25136: Support Apple Xcode 7's new textual SDK stub libraries.
 
+- Issue #24324: Do not enable unreachable code warnings when using
+  gcc as the option does not work correctly in older versions of gcc
+  and has been silently removed as of gcc-4.5.
+
 Windows
 -------
 
diff --git a/aclocal.m4 b/aclocal.m4
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1,6 +1,6 @@
-# generated automatically by aclocal 1.14.1 -*- Autoconf -*-
+# generated automatically by aclocal 1.15 -*- Autoconf -*-
 
-# Copyright (C) 1996-2013 Free Software Foundation, Inc.
+# Copyright (C) 1996-2014 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
diff --git a/configure b/configure
--- a/configure
+++ b/configure
@@ -6963,16 +6963,25 @@
 
      CFLAGS="$save_CFLAGS"
      CC="$ac_save_cc"
+
+    # Don't enable unreachable code warning in debug mode, since it usually
+    # results in non-standard code paths.
+    # Issue #24324: Unfortunately, the unreachable code warning does not work
+    # correctly on gcc and has been silently removed from the compiler.
+    # It is supported on clang but on OS X systems gcc may be an alias
+    # for clang.  Try to determine if the compiler is not really gcc and,
+    # if so, only then enable the warning.
+    if test $ac_cv_enable_unreachable_code_warning = yes && \
+        test "$Py_DEBUG" != "true" && \
+        test -z "`$CC --version 2>/dev/null | grep 'Free Software Foundation'`"
+    then
+      BASECFLAGS="$BASECFLAGS -Wunreachable-code"
+    else
+      ac_cv_enable_unreachable_code_warning=no
+    fi
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_enable_unreachable_code_warning" >&5
 $as_echo "$ac_cv_enable_unreachable_code_warning" >&6; }
 
-    # Don't enable unreachable code warning in debug mode, since it usually
-    # results in non-standard code paths.
-    if test $ac_cv_enable_unreachable_code_warning = yes && test "$Py_DEBUG" != "true"
-    then
-      BASECFLAGS="$BASECFLAGS -Wunreachable-code"
-    fi
-
     # if using gcc on alpha, use -mieee to get (near) full IEEE 754
     # support.  Without this, treatment of subnormals doesn't follow
     # the standard.
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -1483,14 +1483,23 @@
 	 ]))
      CFLAGS="$save_CFLAGS"
      CC="$ac_save_cc"
-    AC_MSG_RESULT($ac_cv_enable_unreachable_code_warning)
 
     # Don't enable unreachable code warning in debug mode, since it usually
     # results in non-standard code paths.
-    if test $ac_cv_enable_unreachable_code_warning = yes && test "$Py_DEBUG" != "true"
+    # Issue #24324: Unfortunately, the unreachable code warning does not work
+    # correctly on gcc and has been silently removed from the compiler.
+    # It is supported on clang but on OS X systems gcc may be an alias
+    # for clang.  Try to determine if the compiler is not really gcc and,
+    # if so, only then enable the warning.
+    if test $ac_cv_enable_unreachable_code_warning = yes && \
+        test "$Py_DEBUG" != "true" && \
+        test -z "`$CC --version 2>/dev/null | grep 'Free Software Foundation'`"
     then
       BASECFLAGS="$BASECFLAGS -Wunreachable-code"
+    else
+      ac_cv_enable_unreachable_code_warning=no
     fi
+    AC_MSG_RESULT($ac_cv_enable_unreachable_code_warning)
 
     # if using gcc on alpha, use -mieee to get (near) full IEEE 754
     # support.  Without this, treatment of subnormals doesn't follow

-- 
Repository URL: https://hg.python.org/cpython