From 97d3b04c9b4ac50f9110001a772d59590a6f6274 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 10 Oct 2014 14:20:20 +0000
Subject: ruby/ruby.h: fix for older gcc

* configure.in (__builtin_choose_expr_constant_p): in gcc 4.8 or
  earlier, __builtin_choose_expr() does not consider
  __builtin_constant_p(variable) a constant expression.

* include/ruby/ruby.h (RUBY_SAFE_LEVEL_CHECK): fix for older gcc.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47867 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 configure.in        |  3 ++-
 include/ruby/ruby.h | 19 ++++++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/configure.in b/configure.in
index f4651324fe..efb14e7611 100644
--- a/configure.in
+++ b/configure.in
@@ -2110,7 +2110,7 @@ main(int argc, char **argv)
 AC_DEFUN([RUBY_CHECK_BUILTIN_FUNC], [dnl
 AC_CACHE_CHECK([for $1], AS_TR_SH(rb_cv_builtin_$1),
   [AC_LINK_IFELSE(
-    [AC_LANG_PROGRAM([], [$2;])],
+    [AC_LANG_PROGRAM([int foo;], [$2;])],
     [AS_TR_SH(rb_cv_builtin_$1)=yes],
     [AS_TR_SH(rb_cv_builtin_$1)=no])])
 if test "${AS_TR_SH(rb_cv_builtin_$1)}" != no; then
@@ -2123,6 +2123,7 @@ RUBY_CHECK_BUILTIN_FUNC(__builtin_clz, [__builtin_clz(0)])
 RUBY_CHECK_BUILTIN_FUNC(__builtin_clzl, [__builtin_clzl(0)])
 RUBY_CHECK_BUILTIN_FUNC(__builtin_clzll, [__builtin_clzll(0)])
 RUBY_CHECK_BUILTIN_FUNC(__builtin_choose_expr, [__builtin_choose_expr(0, 0, 0)])
+RUBY_CHECK_BUILTIN_FUNC(__builtin_choose_expr_constant_p, [__builtin_choose_expr(__builtin_constant_p(foo), 0, 0)])
 RUBY_CHECK_BUILTIN_FUNC(__builtin_types_compatible_p, [__builtin_types_compatible_p(int, int)])
 
 if test "$ac_cv_func_qsort_r" != no; then
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index dbea8e4c67..539c1b3f63 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -564,11 +564,24 @@ int ruby_safe_level_4_warning(void) __attribute__((warning("$SAFE=4 is obsolete"
 # ifdef RUBY_EXPORT
 #   define ruby_safe_level_4_warning() ruby_safe_level_4_error()
 # endif
-#define RUBY_SAFE_LEVEL_INVALID_P(level) \
+#if defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P)
+# define RUBY_SAFE_LEVEL_INVALID_P(level) \
+    __extension__(\
+	__builtin_choose_expr(\
+	    __builtin_constant_p(level), \
+	    ((level) < 0 || RUBY_SAFE_LEVEL_MAX < (level)), 0))
+# define RUBY_SAFE_LEVEL_CHECK(level, type) \
+    __extension__(__builtin_choose_expr(RUBY_SAFE_LEVEL_INVALID_P(level), ruby_safe_level_4_##type(), (level)))
+#else
+/* in gcc 4.8 or earlier, __builtin_choose_expr() does not consider
+ * __builtin_constant_p(variable) a constant expression.
+ */
+# define RUBY_SAFE_LEVEL_INVALID_P(level) \
     __extension__(__builtin_constant_p(level) && \
 		  ((level) < 0 || RUBY_SAFE_LEVEL_MAX < (level)))
-#define RUBY_SAFE_LEVEL_CHECK(level, type) \
-    __extension__(__builtin_choose_expr(RUBY_SAFE_LEVEL_INVALID_P(level), ruby_safe_level_4_##type(), (level)))
+# define RUBY_SAFE_LEVEL_CHECK(level, type) \
+    (RUBY_SAFE_LEVEL_INVALID_P(level) ? ruby_safe_level_4_##type() : (level))
+#endif
 #define rb_secure(level) rb_secure(RUBY_SAFE_LEVEL_CHECK(level, warning))
 #define rb_set_safe_level(level) rb_set_safe_level(RUBY_SAFE_LEVEL_CHECK(level, error))
 #endif
-- 
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