[RFA] fix Ada SYMBOL_PRINT_NAME problem

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

The debugger sometimes prints weird names for certain Ada entities.
This shows up inside multiple-choice menus printed when an expression
is ambiguous. For instance, given the following two variables declared
with the same name but in a different (global) scope:

   package First is
      I : Integer := 1;
   end First;

   package Second is
      I : Integer := 2;
   end Second;

Trying to print "i" will result in the following menu:

    (gdb) print i
    Multiple matches for i
    [0] cancel
    [1] pck__first(int) at pck.adb:3
    [2] pck__second(int) at pck.adb:7
    >

The expected output (particularly for choices 1 and 2) is:

    (gdb) p i
    Multiple matches for i
    [0] cancel
    [1] pck.first.i at pck.adb:3
    [2] pck.second.i at pck.adb:7
    > 

What happened in our case is that symtab.c:symbol_natural_name
checks for gsymbol->language_specific.cplus_specific.demangled_name,
and if not null, returns it. For Ada symbols, we expect this field
to be not null (as a side question, I wonder why we even check this
field when dealing with Ada symbols at all, but that's a separate
question - I will ask Paul).  The following comment that I added
with the patch explains why:

     Unfortunately, there is a case that we have to watch out for:
     During the symbol table processing, when creating the minimal
     symbols, we don't know the language associated to each entry.
     As a result, symbol_find_demangled_name tries various non-Ada
     demanglers, and sometimes, a demangler accepts the symbol and
     returns an unexpected demangled form of our symbol name.  This
     has consequences during the debugging info processing: This time,
     we do know the language, but since we have already found an entry
     in the demangled_name_hash using the linkage name, we use the
     demangled name stored in the hash instead of trying to recompute it.

So we had to add an explicit guard for Ada languages inside
symtab.c:symbol_set_names to make sure that Ada symbol do not
unexpectedly get the demangled_name field set.

2008-01-08  Joel Brobecker  <brobecker@adacore.com>

        * symtab.c (symbol_set_names): Do not set the demangled_name
        for Ada symbols.

I also wrote a small testcase.

2008-01-08  Joel Brobecker  <brobecker@adacore.com>

        * gdb.ada/sym_print_name: New test program.
        * gdb.ada/sym_print_name.exp: New testcase.

Tested on x86-linux, no regression.
OK to commit?

Thanks,
-- 
Joel

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