svn commit: r359681 - in head: . share/mk

[Brooks Davis]

Author: brooks
Date: Mon Apr  6 23:38:46 2020
New Revision: 359681
URL: https://svnweb.freebsd.org/changeset/base/359681

Log:
  Fix compilation with upstream clang builtin headers.
  
  By using -nobuiltininc and adding the clang builtin headers resource dir
  to the end of the compiler header search path, we can still find headers
  such as immintrin.h but find the FreeBSD version of stddef.h/stdarg.h/..
  first.
  
  This is a workaround until we are able to settle on and complete a plan
  to harmonize guard macros with LLVM.  We've mostly worked out this on
  FreeBSD systems by removing select headers from the installed set of
  devel/llvm*, but that isn't a good solution for cross build.
  
  Submitted by:	arichardson
  Obtained from:	CheriBSD
  Sponsored by:	DARPA, AFRL
  Differential Revision:	https://reviews.freebsd.org/D17002

Modified:
  head/Makefile.inc1
  head/share/mk/bsd.compiler.mk
  head/share/mk/bsd.sys.mk

Modified: head/Makefile.inc1
==============================================================================
--- head/Makefile.inc1	Mon Apr  6 23:28:24 2020	(r359680)
+++ head/Makefile.inc1	Mon Apr  6 23:38:46 2020	(r359681)
@@ -337,6 +337,7 @@ _TOOLCHAIN_METADATA_VARS=	COMPILER_VERSION \
 				COMPILER_TYPE \
 				COMPILER_FEATURES \
 				COMPILER_FREEBSD_VERSION \
+				COMPILER_RESOURCE_DIR \
 				LINKER_VERSION \
 				LINKER_FEATURES \
 				LINKER_TYPE \

Modified: head/share/mk/bsd.compiler.mk
==============================================================================
--- head/share/mk/bsd.compiler.mk	Mon Apr  6 23:28:24 2020	(r359680)
+++ head/share/mk/bsd.compiler.mk	Mon Apr  6 23:38:46 2020	(r359681)
@@ -143,7 +143,7 @@ _cc_vars+=XCC X_
 # The value is only used/exported for the same environment that impacts
 # CC and COMPILER_* settings here.
 _exported_vars=	${X_}COMPILER_TYPE ${X_}COMPILER_VERSION \
-		${X_}COMPILER_FREEBSD_VERSION
+		${X_}COMPILER_FREEBSD_VERSION ${X_}COMPILER_RESOURCE_DIR
 ${X_}_cc_hash=	${${cc}}${MACHINE}${PATH}
 ${X_}_cc_hash:=	${${X_}_cc_hash:hash}
 # Only import if none of the vars are set somehow else.
@@ -201,6 +201,10 @@ ${X_}COMPILER_FREEBSD_VERSION=	unknown
 .endif
 .endif
 
+.if !defined(${X_}COMPILER_RESOURCE_DIR)
+${X_}COMPILER_RESOURCE_DIR!=	${${cc}:N${CCACHE_BIN}} -print-resource-dir 2>/dev/null || echo unknown
+.endif
+
 ${X_}COMPILER_FEATURES=
 .if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 30300) || \
 	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 40800)
@@ -224,6 +228,7 @@ X_COMPILER_TYPE=	${COMPILER_TYPE}
 X_COMPILER_VERSION=	${COMPILER_VERSION}
 X_COMPILER_FREEBSD_VERSION=	${COMPILER_FREEBSD_VERSION}
 X_COMPILER_FEATURES=	${COMPILER_FEATURES}
+X_COMPILER_RESOURCE_DIR=	${COMPILER_RESOURCE_DIR}
 .endif	# ${cc} == "CC" || (${cc} == "XCC" && ${XCC} != ${CC})
 
 # Export the values so sub-makes don't have to look them up again, using the

Modified: head/share/mk/bsd.sys.mk
==============================================================================
--- head/share/mk/bsd.sys.mk	Mon Apr  6 23:28:24 2020	(r359680)
+++ head/share/mk/bsd.sys.mk	Mon Apr  6 23:38:46 2020	(r359681)
@@ -206,6 +206,21 @@ CWARNFLAGS+=	-Wno-unknown-pragmas
 # This warning is utter nonsense
 CFLAGS+=	-Wno-format-zero-length
 
+.if ${COMPILER_TYPE} == "clang"
+# The headers provided by clang are incompatible with the FreeBSD headers.
+# If the version of clang is not one that has been patched to omit the
+# incompatible headers, we need to compile with -nobuiltininc and add the
+# resource dir to the end of the search paths. This ensures that headers such as
+# immintrin.h are still found but stddef.h, etc. are picked up from FreeBSD.
+#
+# XXX: This is a hack to support complete external installs of clang while
+# we work to synchronize our decleration guards with those in the clang tree.
+.if ${MK_CLANG_BOOTSTRAP} == "no" && ${COMPILER_RESOURCE_DIR} != "unknown" && \
+    !defined(BOOTSTRAPPING)
+CFLAGS+=-nobuiltininc -idirafter ${COMPILER_RESOURCE_DIR}/include
+.endif
+.endif
+
 CLANG_OPT_SMALL= -mstack-alignment=8 -mllvm -inline-threshold=3\
 		 -mllvm -simplifycfg-dup-ret
 .if ${COMPILER_VERSION} >= 30500 && ${COMPILER_VERSION} < 30700