[RFC 01/19] kbuild: Fixes to rules for host-cshlib and host-cxxshlib

Knut Omang
2019-08-13T06:13:22Z

C++ libraries interfacing to C APIs might sometimes need some glue
logic more easily written in C.
Allow a C++ library to also contain 0 or more C objects.

Also fix rules for both C and C++ shared libraries:
- C++ shared libraries depended on .c instead of .cc files
- Rules were referenced as -objs instead of the intended
-cobjs and -cxxobjs following the pattern from hostprogs*.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
---
scripts/Makefile.host | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index b6a54bd..4e9bb21 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -46,8 +46,10 @@ host-cxxmulti := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))

# Object (.o) files used by the shared libaries
-host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
-host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
+# Note: C++ libraries may contain both C and C++ objects, compiled differently:
+host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-cshobjs))))
+host-cshobjs += $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-cshobjs))))
+host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-cxxshobjs))))

host-csingle := $(addprefix $(obj)/,$(host-csingle))
host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
@@ -130,14 +132,10 @@ quiet_cmd_host-cshobjs = HOSTCC -fPIC $@
$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
$(call if_changed_dep,host-cshobjs)

-# Compile .c file, create position independent .o file
-# Note that plugin capable gcc versions can be either C or C++ based
-# therefore plugin source files have to be compilable in both C and C++ mode.
-# This is why a C++ compiler is invoked on a .c file.
-# host-cxxshobjs -> .o
+# Compile .cc (C++) file, create position independent .o file
quiet_cmd_host-cxxshobjs = HOSTCXX -fPIC $@
cmd_host-cxxshobjs = $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $<
-$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
+$(host-cxxshobjs): $(obj)/%.o: $(src)/%.cc FORCE
$(call if_changed_dep,host-cxxshobjs)

# Link a shared library, based on position independent .o files
@@ -154,7 +152,8 @@ $(call multi_depend, $(host-cshlib), .so, -objs)
# *.o -> .so shared library (host-cxxshlib)
quiet_cmd_host-cxxshlib = HOSTLLD -shared $@
cmd_host-cxxshlib = $(HOSTCXX) $(KBUILD_HOSTLDFLAGS) -shared -o $@ \
- $(addprefix $(obj)/,$($(@F:.so=-objs))) \
+ $(addprefix $(obj)/,$($(@F:.so=-cshobjs))) \
+ $(addprefix $(obj)/,$($(@F:.so=-cxxshobjs))) \
$(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
$(host-cxxshlib): FORCE
$(call if_changed,host-cxxshlib)
--
git-series 0.9.1