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-rw-r--r--Makeconfig3
-rw-r--r--Makerules24
2 files changed, 26 insertions, 1 deletions
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..0960412ed5 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+# the target is out of date.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 $(before-compile)
+cstdlib=$(shell echo "\#include <cstdlib>" | $(CXX) -M -MP -x c++ - \
+ | grep cstdlib: | sed -e "s/:$$//")
+$(common-objpfx)cstdlib: $(cstdlib)
+ $(INSTALL_DATA) $< $@T
+ $(move-if-change) $@T $@
+before-compile := $(common-objpfx)cmath $(before-compile)
+cmath=$(shell echo "\#include <cmath>" | $(CXX) -M -MP -x c++ - \
+ | grep cmath: | sed -e "s/:$$//")
+$(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 \