Linking in C++ compilers (including g++) causes references to be created
with their arguments. Due to this, trace library headers included into
C++ code base will cause their objects to built with symbols with
arguments. Apparently this is to support operator overloading in C++.
This causes linker errors. For example, here's what I get when I try to
link libtracecmd with a main.o built from a C++ main.cc source file.
main.cc:(.text+0x90):
undefined reference to `tracecmd_get_tep(tracecmd_input*)'
undefined reference to `tracecmd_free_record(tep_record*)'
undefined reference to `tracecmd_read_data(tracecmd_input*, int)'
The standard fix for this is to wrap the C project's header in
extern "C".
With this patch, I am able to link libtracecmd into a C++
code base.
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
include/trace-cmd/trace-cmd.h | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 4963f45..b050233 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -9,6 +9,10 @@
#include "event-parse.h"
#include "tracefs.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+
struct tracecmd_input;
enum tracecmd_open_flags {
@@ -78,5 +82,8 @@ struct tracecmd_filter *tracecmd_filter_add(struct tracecmd_input *handle,
const char *filter_str, bool neg);
enum tracecmd_filters tracecmd_filter_match(struct tracecmd_filter *filter,
struct tep_record *record);
+#ifdef __cplusplus
+}
+#endif
#endif /* _TRACE_CMD_H */
--
2.25.1
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