reflect: ensure uniqueness of type descriptors on AIX.

On AIX, duplication of type descriptors can occur if one is
declared in the libgo and one in the Go program being compiled.
The AIX linker isn't able to merge them together as Linux one does.
One solution is to always load libgo first but that needs a huge mechanism in
gcc core. Thus, this patch ensures that the duplication isn't visible
for the end user.

In reflect and internal/reflectlite, the comparison of rtypes is made on their
name and not only on their addresses.

In reflect, toType() function is using a canonicalization map to force rtypes
having the same rtype.String() to return the same Type. This can't be made in
internal/reflectlite as it needs sync package. But, for now, it doesn't matter
as internal/reflectlite is not widely used.

Fixes golang/go#39276

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/260158

1 files changed, 4 insertions, 0 deletions

diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 18b1a06be41..59a7083f614 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -1114,6 +1114,10 @@ runtime_internal_sys_lo_check_GOCFLAGS = -fgo-compiling-runtime
 # Also use -fno-inline to get better results from the memory profiler.
 runtime_pprof_check_GOCFLAGS = -static-libgo -fno-inline
 
+# reflect tests must be done with -static-libgo. Otherwize,
+# there will be a duplication of the canonicalization map.
+@LIBGO_IS_AIX_TRUE@reflect_check_GOCFLAGS = -static-libgo -Wl,-bbigtoc
+
 # Use -static for the syscall tests if possible, because otherwise when
 # running as root the re-execs ignore LD_LIBRARY_PATH.
 @HAVE_STATIC_LINK_TRUE@syscall_check_GOCFLAGS = -static