[Bug ada/107475] New: [10/11/12/13 Regression] libgnat fails to link libgnat.so on systems with older glibc on x86_64-linux-gnux32

["doko at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107475

            Bug ID: 107475
           Summary: [10/11/12/13 Regression] libgnat fails to link
                    libgnat.so on systems with older glibc on
                    x86_64-linux-gnux32
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at gcc dot gnu.org
  Target Milestone: ---

This was introduced with the fix and backports of PR103530 on
x86_64-linux-gnux32 with older glibc versions (checked with 2.31), where dladdr
is still in the libdl.so library, and not included in libc.so as in newer glibc
versions.


[...]
/usr/x86_64-linux-gnux32/bin/ld: s-trasym.o: in function
`system__traceback__symbolic__module_na
me__getXnn':
collect2: error: ld returned 1 exit status
make[8]: *** [gcc-interface/Makefile:677: gnatlib-shared-default] Error 1

https://gcc.gnu.org/git/?p=gcc.git;a=patch;h=9d6c63ba490ec92245f04b5cbafc56abd28e8d22

-- a/gcc/ada/Makefile.rtl
+++ b/gcc/ada/Makefile.rtl
@@ -2650,13 +2650,18 @@ ifeq ($(strip $(filter-out %x32 linux%,$(target_cpu)
$(target_os))),)
   s-tasinf.adb<libgnarl/s-tasinf__linux.adb \
   s-tpopsp.adb<libgnarl/s-tpopsp__tls.adb \
   s-taspri.ads<libgnarl/s-taspri__posix.ads \
+  $(TRASYM_DWARF_UNIX_PAIRS) \
+  s-tsmona.adb<libgnat/s-tsmona__linux.adb \
   $(ATOMICS_TARGET_PAIRS) \
   $(X86_64_TARGET_PAIRS) \
+  $(GNATRTL_128BIT_PAIRS) \
   system.ads<libgnat/system-linux-x86.ads

The addition of s-tsmona.adb<libgnat/s-tsmona__linux.adb pulls in the reference
to dladdr, however not setting MISCLIB to -ldl as on other architectures

Proposed patch:

--- a/gcc/ada/Makefile.rtl
+++ b/gcc/ada/Makefile.rtl
@@ -2584,6 +2584,7 @@ ifeq ($(strip $(filter-out %x32 linux%,$(target_cpu)
$(target_os))),)
   EXTRA_GNATRTL_TASKING_OBJS=s-linux.o a-exetim.o
   EH_MECHANISM=-gcc
   THREADSLIB=-lpthread -lrt
+  MISCLIB = -ldl
   GNATLIB_SHARED=gnatlib-shared-dual
   GMEM_LIB = gmemlib
   LIBRARY_VERSION := $(LIB_VERSION)