[RFC PATCH] libxfs: compile with a C++ compiler

Darrick J. Wong
2024-08-27T23:45:34Z

From: Darrick J. Wong <djwong@kernel.org>

Apparently C++ compilers don't like the implicit void* casts that go on
in the system headers. Compile a dummy program with the C++ compiler to
make sure this works, so Darrick has /some/ chance of figuring these
things out before the users do.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
configure.ac | 1 +
include/builddefs.in | 7 +++++++
libxfs/Makefile | 8 +++++++-
libxfs/dummy.cpp | 15 +++++++++++++++
4 files changed, 30 insertions(+), 1 deletion(-)
create mode 100644 libxfs/dummy.cpp

diff --git a/configure.ac b/configure.ac
index 0ffe2e5dfc53..04544f85395b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,6 +9,7 @@ AC_PROG_INSTALL
LT_INIT

AC_PROG_CC
+AC_PROG_CXX
AC_ARG_VAR(BUILD_CC, [C compiler for build tools])
if test "${BUILD_CC+set}" != "set"; then
if test $cross_compiling = no; then
diff --git a/include/builddefs.in b/include/builddefs.in
index 44f95234d21b..0f312b8b88fe 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -14,6 +14,7 @@ MALLOCLIB = @malloc_lib@
LOADERFLAGS = @LDFLAGS@
LTLDFLAGS = @LDFLAGS@
CFLAGS = @CFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wno-address-of-packed-member
+CXXFLAGS = @CXXFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wno-address-of-packed-member
BUILD_CFLAGS = @BUILD_CFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64

# make sure we don't pick up whacky LDFLAGS from the make environment and
@@ -234,9 +235,15 @@ ifeq ($(ENABLE_GETTEXT),yes)
GCFLAGS += -DENABLE_GETTEXT
endif

+# Override these if C++ needs other options
+SANITIZER_CXXFLAGS = $(SANITIZER_CFLAGS)
+GCXXFLAGS = $(GCFLAGS)
+PCXXFLAGS = $(PCFLAGS)
+
BUILD_CFLAGS += $(GCFLAGS) $(PCFLAGS)
# First, Sanitizer, Global, Platform, Local CFLAGS
CFLAGS += $(FCFLAGS) $(SANITIZER_CFLAGS) $(OPTIMIZER) $(GCFLAGS) $(PCFLAGS) $(LCFLAGS)
+CXXFLAGS += $(FCXXFLAGS) $(SANITIZER_CXXFLAGS) $(OPTIMIZER) $(GCXXFLAGS) $(PCXXFLAGS) $(LCXXFLAGS)

include $(TOPDIR)/include/buildmacros

diff --git a/libxfs/Makefile b/libxfs/Makefile
index 1185a5e6cb26..bb851ab74204 100644
--- a/libxfs/Makefile
+++ b/libxfs/Makefile
@@ -125,6 +125,8 @@ CFILES = buf_mem.c \
xfs_trans_space.c \
xfs_types.c

+LDIRT += dummy.o
+
#
# Tracing flags:
# -DMEM_DEBUG all zone memory use
@@ -144,7 +146,11 @@ LTLIBS = $(LIBPTHREAD) $(LIBRT)
# don't try linking xfs_repair with a debug libxfs.
DEBUG = -DNDEBUG

-default: ltdepend $(LTLIBRARY)
+default: ltdepend $(LTLIBRARY) dummy.o
+
+dummy.o: dummy.cpp
+ @echo " [CXX] $@"
+ $(Q)$(CC) $(CXXFLAGS) -c $<

# set up include/xfs header directory
include $(BUILDRULES)
diff --git a/libxfs/dummy.cpp b/libxfs/dummy.cpp
new file mode 100644
index 000000000000..a872c00ad84b
--- /dev/null
+++ b/libxfs/dummy.cpp
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "include/xfs.h"
+#include "include/handle.h"
+#include "include/jdm.h"
+
+/* Dummy program to test C++ compilation of user-exported xfs headers */
+
+int main(int argc, char *argv[])
+{
+ return 0;
+}