[Bug gdb/25663] New: dwarf2_name caching bug

["vcollod at nvidia dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=25663

            Bug ID: 25663
           Summary: dwarf2_name caching bug
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: vcollod at nvidia dot com
  Target Milestone: ---

Hello!

While working on cuda-gdb, I noticed dwarf2_name does not behave as described.

It's supposed to return the name of a dwarf DIE, as described by the following
comment:

/* Get name of a die, return NULL if not found. Anonymous namespaces are
converted to their magic string. */

It does some processing, stores the results into a cache, then strips the C++
namespaces of the name. The last step should probably be done before storing
the result into the cache.

The following code sample should help reproduce the issue.

I did not fix it myself as I am concerned some code relies on this odd
behavior.

cat > dwarf2_name_repro.gdb <<EOF
b dwarf2_name
run
while 1
      fin
      printf "logged dwarf2_name(%p) = %s\n", (size_t)die, $
      continue
end
EOF

cat > dwarf2_name_repro.cc <<EOF
namespace TestSpace {
        typedef struct {
                int a;
        } type;
}

int main() {
        TestSpace::type test{42};
        return test.a;
}
EOF

make CFLAGS='-O0 -g' dwarf2_name_repro

gdb -q -batch -x dwarf2_name_repro.gdb -arg PATH_TO_GDB_WITH_DEBUG_INFO -ex
'quit' ./dwarf2_name_repro | grep logged | grep type

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