From 8321286846970af562a2ff6b7272f1cd0860d6c1 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 5 Jul 2016 15:01:33 -0700
Subject: Make copies of cstdlib/cmath and use them [BZ #20314]

If C++ headers <cstdlib> or <cmath> are used, GCC 6 will include
/usr/include/stdlib.h or /usr/include/math.h from "#include_next"
(instead of stdlib/stdlib.h or math/math.h in the glibc source
directory), and this turns up as a make dependency.  An implicit
rule will kick in and make will try to install stdlib/stdlib.h or
math/math.h as /usr/include/stdlib.h or /usr/include/math.h because
the target is out of date.  We make a copy of <cstdlib> and <cmath>
in the glibc build directory so that stdlib/stdlib.h and math/math.h
will be used instead of /usr/include/stdlib.h and /usr/include/math.h.

	[BZ #20314]
	* Makeconfig (CXXFLAGS): Prepend -I$(common-objpfx).
	* Makerules (before-compile): Add $(common-objpfx)cstdlib and
	$(common-objpfx)cmath.
	($(common-objpfx)cstdlib): New target.
	($(common-objpfx)cmath): Likewise.
---
 ChangeLog  |  9 +++++++++
 Makeconfig |  3 ++-
 Makerules  | 24 ++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index fc313b4307..8b1fa85fd7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2016-07-05  H.J. Lu  <hongjiu.lu@intel.com>
+
+	[BZ #20314]
+	* Makeconfig (CXXFLAGS): Prepend -I$(common-objpfx).
+	* Makerules (before-compile): Add $(common-objpfx)cstdlib and
+	$(common-objpfx)cmath.
+	($(common-objpfx)cstdlib): New target.
+	($(common-objpfx)cmath): Likewise.
+
 2016-07-05  Chris Metcalf  <cmetcalf@mellanox.com>
 
 	* malloc/tst-malloc-thread-fail.c (TIMEOUT): Bump up to 30s.
diff --git a/Makeconfig b/Makeconfig
index 901e253453..03fd89c13e 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -889,7 +889,8 @@ override CFLAGS	= -std=gnu11 -fgnu89-inline $(config-extra-cflags) \
 		  $(CFLAGS-$(@F)) $(tls-model) \
 		  $(foreach lib,$(libof-$(basename $(@F))) \
 				$(libof-$(<F)) $(libof-$(@F)),$(CFLAGS-$(lib)))
-override CXXFLAGS = $(c++-sysincludes) \
+# Use our copies of cstdlib and cmath.
+override CXXFLAGS = -I$(common-objpfx) $(c++-sysincludes) \
 		    $(filter-out %frame-pointer,$(+cflags)) $(sysdep-CFLAGS) \
 		    $(CFLAGS-$(suffix $@)) $(CFLAGS-$(<F)) $(CFLAGS-$(@F))
 
diff --git a/Makerules b/Makerules
index f1ecd40393..7e4077ee50 100644
--- a/Makerules
+++ b/Makerules
@@ -109,6 +109,30 @@ endif # avoid-generated
 endif # $(build-shared) = yes
 
 ifndef avoid-generated
+ifneq (,$(CXX))
+# If C++ headers <cstdlib> or <cmath> are used, GCC 6 will include
+# /usr/include/stdlib.h or /usr/include/math.h from "#include_next"
+# (instead of stdlib/stdlib.h or math/math.h in the glibc source
+# directory), and this turns up as a make dependency.  An implicit
+# rule will kick in and make will try to install stdlib/stdlib.h or
+# math/math.h as /usr/include/stdlib.h or /usr/include/math.h because
+# the target is out of date.  We make a copy of <cstdlib> and <cmath>
+# in the glibc build directory so that stdlib/stdlib.h and math/math.h
+# will be used instead of /usr/include/stdlib.h and /usr/include/math.h.
+before-compile := $(common-objpfx)cstdlib $(common-objpfx)cmath \
+	          $(before-compile)
+cstdlib=$(shell echo "\#include <cstdlib>" | $(CXX) -M -MP -x c++ - \
+		| sed -n "/cstdlib:/{s/:$$//;p}")
+$(common-objpfx)cstdlib: $(cstdlib)
+	$(INSTALL_DATA) $< $@T
+	$(move-if-change) $@T $@
+cmath=$(shell echo "\#include <cmath>" | $(CXX) -M -MP -x c++ - \
+		| sed -n "/cmath:/{s/:$$//;p}")
+$(common-objpfx)cmath: $(cmath)
+	$(INSTALL_DATA) $< $@T
+	$(move-if-change) $@T $@
+endif
+
 before-compile := $(common-objpfx)libc-abis.h $(before-compile)
 $(common-objpfx)libc-abis.h: $(common-objpfx)libc-abis.stamp; @:
 $(common-objpfx)libc-abis.stamp: $(..)scripts/gen-libc-abis \
-- 
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