UNDEF := $(BINDIR)newlib/syscalls.o $(UNDEF)

# Search for Newlib include directories

# Since Clang is not installed as a separate instance for each crossdev target
# we need to tell it where to look for platform specific includes (Newlib
# headers instead of Linux/Glibc headers.)
# On GCC this is done when building the cross compiler toolchain so we do not
# actually need to specify the include paths for system includes.
# Ubuntu gcc-arm-embedded toolchain (https://launchpad.net/gcc-arm-embedded)
# places newlib headers in several places, but the primary source seem to be
# /etc/alternatives/gcc-arm-none-eabi-include
# Gentoo Linux crossdev place the newlib headers in /usr/arm-none-eabi/include
# Arch Linux also place the newlib headers in /usr/arm-none-eabi/include
# Ubuntu seem to put a copy of the newlib headers in the same place as
# Gentoo crossdev, but we prefer to look at /etc/alternatives first.
# On OSX, newlib includes are possibly located in
# /usr/local/opt/arm-none-eabi*/arm-none-eabi/include
NEWLIB_INCLUDE_PATTERNS ?= \
  /etc/alternatives/gcc-$(TARGET_TRIPLE)-include \
  /usr/$(TARGET_TRIPLE)/include \
  /usr/local/opt/$(TARGET_TRIPLE)*/$(TARGET_TRIPLE)/include \
  #
# Use the wildcard Makefile function to search for existing directories matching
# the patterns above. We use the -isystem gcc/clang argument to add the include
# directories as system include directories, which means they will not be
# searched until after all the project specific include directories (-I/path)
NEWLIB_INCLUDES ?= \
    $(foreach dir, \
        $(foreach pat, $(NEWLIB_INCLUDE_PATTERNS), $(wildcard $(pat))), \
        -isystem $(dir))

export INCLUDES += $(NEWLIB_INCLUDES)