From 74a2f8ffb83172de1af0da6751a65c08a722986f Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Mon, 1 Jan 2018 22:41:36 -0500 Subject: [PATCH] treat Ada DW_TAG_unspecified_type DIEs as stub types Consider the gdb.ada/taft_type.exp testcase, which exercises the situation where a variable is defined using a type which is a pointer to an incomplete type, with the actual type definition being provided by another unit. Up to now, the strategy used by GNAT when generating the DWARF debugging info was to produce a incomplete DW_TAG_enumeration_type DIE with a DW_AT_declaration flag attached to it: .uleb128 0x4 # (DIE (0x3e) DW_TAG_enumeration_type) .long .LASF4 # DW_AT_name: "pck__empty" # DW_AT_declaration However, a more standard way for the compiler to describe this kind of type is to use the DW_TAG_unspecified_type tag. When the compiler is enhanced to do so, we'll need to treat such types as stubs -- we only do so with types from Ada units, however, as the meaning of this TAG is intentionally left permissive and language-specific by the DWARF standard. Without this patch, running the testcase above with an enhanced compiler now yields: (gdb) print w.e.all Attempt to dereference a generic pointer. FAIL: gdb.ada/taft_type.exp: print w.e.all gdb/ChangeLog: * dwarf2read.c (read_unspecified_type): Treat DW_TAG_enumeration_type DIEs from Ada units as stubs. Tested on x86_64-linux, fixes the FAIL in gdb.ada/taft_type.exp above. --- gdb/ChangeLog | 5 +++++ gdb/dwarf2read.c | 9 +++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9eaa15fe3d3..3199eaacc97 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2018-01-02 Joel Brobecker + + * dwarf2read.c (read_unspecified_type): Treat + DW_TAG_enumeration_type DIEs from Ada units as stubs. + 2018-01-01 Joel Brobecker Update copyright year range in all GDB files. diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index b4f5cd1e3c9..4dbd5c35d7b 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -17693,11 +17693,16 @@ read_unspecified_type (struct die_info *die, struct dwarf2_cu *cu) { struct type *type; - /* For now, we only support the C meaning of an unspecified type: void. */ - type = init_type (cu->objfile, TYPE_CODE_VOID, 0, NULL); TYPE_NAME (type) = dwarf2_name (die, cu); + /* In Ada, an unspecified type is typically used when the description + of the type is defered to a different unit. When encountering + such a type, we treat it as a stub, and try to resolve it later on, + when needed. */ + if (cu->language == language_ada) + TYPE_STUB (type) = 1; + return set_die_type (die, type, cu); } -- 2.30.2