From 48b5669c2e26debe49491ecf6e20e82ccf28c15b Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Fri, 3 Oct 2025 10:59:29 -0600 Subject: [PATCH] Ignore artificial fields in Ada A user found an unusual Ada situation that DWARF does not readily support. Consider this type: type Discrete_Typ is tagged null record; type Int_Typ (Is_Static : Boolean) is new Discrete_Typ with null record; type Signed_Int_Typ (Is_Static : Boolean) is new Int_Typ (Is_Static => Is_Static) with record case Is_Static is when True => Field : Integer; when others => null; end case; end record; Here, Signed_Int_Typ has a variant part where the discriminant is stored in a superclass. Anyway, this code caused gnat-llvm to crash. While fixing the crash, I decided to fix this by emitting an anonymous field in Signed_Int_Typ that represents the discriminant. This would allow member DIEs to refer to it -- which I suppose is possibly why DWARF specified that the discriminant should be a member of the variant (though I don't really know; this decision always seemed very strange to me). Making the field anonymous lead to the strange error: Type ... is not a structure or union type. ... which comes from lookup_struct_elt, which fails when an anonymous member of a structure has a non-composite type. This patch includes a fix for this issue. After fixing that, though I decided it would be better if the artificial discriminant were still given a name. So, this patch includes a change to ada_is_ignored_field to ignore artificial fields. Approved-By: Andrew Burgess --- gdb/ada-lang.c | 10 +- gdb/gdbtypes.c | 16 +++- .../gdb.dwarf2/ada-artificial-field.c | 22 +++++ .../gdb.dwarf2/ada-artificial-field.exp | 95 +++++++++++++++++++ 4 files changed, 134 insertions(+), 9 deletions(-) create mode 100644 gdb/testsuite/gdb.dwarf2/ada-artificial-field.c create mode 100644 gdb/testsuite/gdb.dwarf2/ada-artificial-field.exp diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c index 0dfcc104125..cdf7c88d83f 100644 --- a/gdb/ada-lang.c +++ b/gdb/ada-lang.c @@ -6261,10 +6261,12 @@ ada_is_ignored_field (struct type *type, int field_num) { const char *name = type->field (field_num).name (); - /* Anonymous field names should not be printed. - brobecker/2007-02-20: I don't think this can actually happen - but we don't want to print the value of anonymous fields anyway. */ - if (name == NULL) + /* Anonymous field names should not be printed. */ + if (name == nullptr || name[0] == '\0') + return 1; + + /* Skip artificial fields. */ + if (type->field (field_num).is_artificial ()) return 1; /* Normally, fields whose name start with an underscore ("_") diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c index 24e6d0bf8f5..f1c545f173e 100644 --- a/gdb/gdbtypes.c +++ b/gdb/gdbtypes.c @@ -1821,12 +1821,18 @@ lookup_struct_elt (struct type *type, const char *name, int noerr) } else if (!t_field_name || *t_field_name == '\0') { - struct_elt elt - = lookup_struct_elt (type->field (i).type (), name, 1); - if (elt.field != NULL) + struct type *field_type = type->field (i).type (); + enum type_code field_code = check_typedef (field_type)->code (); + + if (field_code == TYPE_CODE_STRUCT || field_code == TYPE_CODE_UNION) { - elt.offset += type->field (i).loc_bitpos (); - return elt; + struct_elt elt + = lookup_struct_elt (type->field (i).type (), name, 1); + if (elt.field != NULL) + { + elt.offset += type->field (i).loc_bitpos (); + return elt; + } } } } diff --git a/gdb/testsuite/gdb.dwarf2/ada-artificial-field.c b/gdb/testsuite/gdb.dwarf2/ada-artificial-field.c new file mode 100644 index 00000000000..231044d1b55 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/ada-artificial-field.c @@ -0,0 +1,22 @@ +/* Copyright 2025 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +unsigned char bytes[] = { 1, 2, 3 }; + +int +main (void) +{ + return 0; +} diff --git a/gdb/testsuite/gdb.dwarf2/ada-artificial-field.exp b/gdb/testsuite/gdb.dwarf2/ada-artificial-field.exp new file mode 100644 index 00000000000..88792b8efa2 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/ada-artificial-field.exp @@ -0,0 +1,95 @@ +# Copyright 2025 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# Test that Ada does not display artificial fields. + +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +require dwarf2_support + +standard_testfile .c -dw.S + +# Make some DWARF for the test. +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble $asm_file { + cu {} { + DW_TAG_compile_unit { + DW_AT_language @DW_LANG_Ada95 + DW_AT_name fd.adb + DW_AT_comp_dir /tmp + } { + declare_labels byte array disc struct + + byte: DW_TAG_base_type { + DW_AT_byte_size 1 DW_FORM_sdata + DW_AT_encoding @DW_ATE_unsigned + DW_AT_name byte + } + + struct: DW_TAG_structure_type { + DW_AT_name anonfield + DW_AT_byte_size 3 DW_FORM_sdata + } { + DW_TAG_member { + DW_AT_name one + DW_AT_type :$byte + DW_AT_data_member_location 0 DW_FORM_sdata + } + DW_TAG_member { + DW_AT_name discr + DW_AT_type :$byte + DW_AT_data_member_location 1 DW_FORM_sdata + DW_AT_artificial 1 DW_FORM_flag + } + DW_TAG_member { + DW_AT_type :$byte + DW_AT_data_member_location 1 DW_FORM_sdata + } + DW_TAG_member { + DW_AT_name two + DW_AT_type :$byte + DW_AT_data_member_location 2 DW_FORM_sdata + } + } + + DW_TAG_variable { + DW_AT_name "value" + DW_AT_type :$struct + DW_AT_external 1 DW_FORM_flag + DW_AT_location { + DW_OP_addr [gdb_target_symbol "bytes"] + } SPECIAL_expr + } + } + } +} + +if {[prepare_for_testing ${testfile}.exp ${testfile} \ + [list $srcfile $asm_file] {nodebug}]} { + return +} + +gdb_test_no_output "set language ada" + +gdb_test "print value" \ + [string_to_regexp " = (one => 1, two => 3)"] + +gdb_test "ptype value" \ + [multi_line \ + "type = record" \ + " one: byte;" \ + " two: byte;" \ + "end record"] -- 2.47.3