[binutils-gdb] [gdb/ada] Fix assert in ada_is_unconstrained_packed_array_type

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=af5300fe24bf2f4e032d639a5396a16c1762b77b

commit af5300fe24bf2f4e032d639a5396a16c1762b77b
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue Dec 7 07:35:10 2021 +0100

    [gdb/ada] Fix assert in ada_is_unconstrained_packed_array_type
    
    On openSUSE Leap 42.3, with system compiler gcc 4.8.5 I run into:
    ...
    (gdb) print u_one_two_three^M
    src/gdb/gdbtypes.h:1050: internal-error: field: \
     Assertion `idx >= 0 && idx < num_fields ()' failed.^M
    ...
    
    We run into trouble while doing this in
    ada_is_unconstrained_packed_array_type:
    ...
    1953          return TYPE_FIELD_BITSIZE (type, 0) > 0;
    ...
    which tries to get field 0 from a type without fields:
    ...
    (gdb) p type->num_fields ()
    $6 = 0
    ...
    which is the case because the type is a typedef:
    ...
    (gdb) p type->code ()
    $7 = TYPE_CODE_TYPEDEF
    ...
    
    Fix this by using the type referenced by the typedef instead.
    
    Tested on x86_64-linux.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28323

Diff:
---
 gdb/ada-lang.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index f8ba05b4276..336d950ec1d 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -1949,6 +1949,8 @@ ada_is_unconstrained_packed_array_type (struct type *type)
       /* The structure's first field is a pointer to an array, so this
 	 fetches the array type.  */
       type = TYPE_TARGET_TYPE (type->field (0).type ());
+      if (type->code () == TYPE_CODE_TYPEDEF)
+	type = ada_typedef_target_type (type);
       /* Now we can see if the array elements are packed.  */
       return TYPE_FIELD_BITSIZE (type, 0) > 0;
     }