[PATCH v4 18/18] selftests/nolibc: allow test -include /path/to/nolibc.h

[Zhangjin Wu]

As the head comment of nolibc-test.c shows, it can be built in 3 ways:

    $(CC) -nostdlib -include /path/to/nolibc.h => NOLIBC already defined
    $(CC) -nostdlib -I/path/to/nolibc/sysroot  => _NOLIBC_* guards are present
    $(CC) with default libc                    => NOLIBC* never defined

Only last two of them are tested currently, let's allow test the first one too.

This may help to find issues about using nolibc.h to build programs. it
derives from this change:

    commit 3a8039e289a3 ("tools/nolibc: Fix build of stdio.h due to header ordering")

Usage:

    // test with sysroot by default
    $ make run-user

    // test without sysroot, using nolibc.h directly
    $ make run-user NOLIBC_SYSROOT=0

Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
 tools/testing/selftests/nolibc/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index b42e67b1a7e2..f42adef87e12 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -126,9 +126,15 @@ sysroot/$(ARCH)/include:
 	$(Q)$(MAKE) -C ../../../include/nolibc ARCH=$(ARCH) OUTPUT=$(CURDIR)/sysroot/ headers_standalone
 	$(Q)mv sysroot/sysroot sysroot/$(ARCH)
 
+ifneq ($(NOLIBC_SYSROOT),0)
 nolibc-test: nolibc-test.c sysroot/$(ARCH)/include
 	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
 	  -nostdlib -static -Isysroot/$(ARCH)/include $< -lgcc
+else
+nolibc-test: nolibc-test.c
+	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
+	  -nostdlib -static -include ../../../include/nolibc/nolibc.h $< -lgcc
+endif
 
 libc-test: nolibc-test.c
 	$(QUIET_CC)$(CC) -o $@ $<
-- 
2.25.1