binutils-gdb/gold/testsuite/weak_as_needed_a.c

extern void bar(void) __attribute__ (( weak ));
extern void t4(void);

void foo(void);

void foo(void)
{
  bar();
  t4();
}
Fix treatment of symbol versions with unused as-needed libraries. When we have a weak reference to a symbol defined in an as-needed library, and that library ends up not-needed, gold simply clears the version information in the symbol table, even if the symbol could have been resolved by a needed library later in the link order. This results in a loss of version information, which can cause the program to bind to the wrong version at run time. This patch lets a dynamic definition override an earlier one if the earlier one is from a not-needed library, so that we can retain the version information from the binding to the needed library. In order to do that, the tracking of needed/not-needed had to be moved up to symbol resolution time, instead of during Symbol_table::set_dynsym_indexes(). In cases where we still end up discarding version information, I've added a warning. For the original problem report and discussion, see: https://stackoverflow.com/questions/50751421/undefined-behavior-in-shared-lib-using-libpthread-but-not-having-it-in-elf-as-d gold/ * resolve.cc (Symbol_table::resolve): Rename tobinding to orig_tobinding. Call set_is_needed() for objects that resolve non-weak references. (Symbol_table::should_override): Allow a dynamic definition to override an earlier one in a not-needed library. * symtab.cc (Symbol_table::set_dynsym_indexes): Remove separate processing for as-needed symbols. Add warning when discarding version informatin. * testsuite/Makefile.am (weak_as_needed): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/weak_as_needed.sh: New test script. * testsuite/weak_as_needed_a.c: New source file. * testsuite/weak_as_needed_b.c: New source file. * testsuite/weak_as_needed_b.script: New version script. * testsuite/weak_as_needed_c.c: New source file. * testsuite/weak_as_needed_c.script: New version script. 2018-06-21 22:51:16 +02:00			`extern void bar(void) __attribute__ (( weak ));`
			`extern void t4(void);`

			`void foo(void);`

			`void foo(void)`
			`{`
			`bar();`
			`t4();`
			`}`