[binutils-gdb] [gdb/symtab] Fix handling of DW_TAG_unspecified_type

[binutils-gdb] [gdb/symtab] Fix handling of DW_TAG_unspecified_type

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a34a90995ae7c2f0c0b79ad32d8087d507fe42db

commit a34a90995ae7c2f0c0b79ad32d8087d507fe42db
Author: Tom de Vries <tdevries@suse.de>
Date:   Sun Sep 11 09:01:03 2022 +0200

    [gdb/symtab] Fix handling of DW_TAG_unspecified_type
    
    Currently, the test-case contained in this patch fails:
    ...
    (gdb) p (int) foo ()^M
    Invalid cast.^M
    (gdb) FAIL: gdb.dwarf2/dw2-unspecified-type.exp: p (int) foo ()
    ...
    because DW_TAG_unspecified_type is translated as void.
    
    There's some code in read_unspecified_type that marks the type as stub, but
    that's only active for ada:
    ...
      if (cu->lang () == language_ada)
        type->set_is_stub (true);
    ...
    
    Fix this by:
    - marking the type as a stub for all languages, and
    - handling the stub return type case in call_function_by_hand_dummy.
    
    Tested on x86_64-linux.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29558

Diff:
---
 gdb/dwarf2/read.c                                  |  6 +-
 gdb/infcall.c                                      |  2 +-
 .../gdb.dwarf2/dw2-unspecified-type-foo.c          | 22 +++++++
 gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c    | 25 ++++++++
 gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp  | 72 ++++++++++++++++++++++
 5 files changed, 123 insertions(+), 4 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 3ca441c4cae..da99402cff0 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -17714,9 +17714,9 @@ read_unspecified_type (struct die_info *die, struct dwarf2_cu *cu)
   /* In Ada, an unspecified type is typically used when the description
      of the type is deferred 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->lang () == language_ada)
-    type->set_is_stub (true);
+     when needed.
+     Mark this as a stub type for all languages though.  */
+  type->set_is_stub (true);
 
   return set_die_type (die, type, cu);
 }
diff --git a/gdb/infcall.c b/gdb/infcall.c
index 2acceed4b07..dd70682bc76 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -814,7 +814,7 @@ call_function_by_hand_dummy (struct value *function,
 	     "target calling convention."),
 	   get_function_name (funaddr, name_buf, sizeof (name_buf)));
 
-  if (values_type == NULL)
+  if (values_type == NULL || values_type->is_stub ())
     values_type = default_return_type;
   if (values_type == NULL)
     {
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type-foo.c b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type-foo.c
new file mode 100644
index 00000000000..b1e3a8b98e4
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type-foo.c
@@ -0,0 +1,22 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2022 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 <http://www.gnu.org/licenses/>.  */
+
+int
+foo (void)
+{
+  asm ("foo_label: .globl foo_label");
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c
new file mode 100644
index 00000000000..e3218205560
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.c
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2022 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 <http://www.gnu.org/licenses/>.  */
+
+extern int foo (void);
+
+int
+main (void)
+{
+  int res = foo ();
+  return res;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp
new file mode 100644
index 00000000000..20c31dc5740
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-unspecified-type.exp
@@ -0,0 +1,72 @@
+# Copyright 2022 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 <http://www.gnu.org/licenses/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile .c -foo.c dwz.S
+
+set foo_res \
+    [function_range foo \
+	 [list ${srcdir}/${subdir}/$srcfile ${srcdir}/${subdir}/$srcfile2]]
+lassign $foo_res \
+    foo_start foo_len
+set foo_end "$foo_start + $foo_len"
+
+# Create the DWARF.
+set asm_file [standard_output_file $srcfile3]
+Dwarf::assemble $asm_file {
+    global foo_start foo_end
+    declare_labels unspecified_type_label
+
+    cu {} {
+	compile_unit {
+	    {language @DW_LANG_Mips_Assembler}
+	} {
+	    unspecified_type_label: unspecified_type {}
+
+	    DW_TAG_subprogram {
+		{name foo}
+		{low_pc $foo_start addr}
+		{high_pc $foo_end addr}
+		{type :$unspecified_type_label}
+	    }
+
+	}
+    }
+}
+
+if [prepare_for_testing "failed to prepare" $testfile \
+	"${asm_file} ${srcfile} ${srcfile2}" {}] {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+# Print the function type.  Return type should be stub type, which is printed
+# as void.
+gdb_test "ptype foo" "type = void \\(void\\)"
+
+# Call the function, casting the function to the correct function type.
+gdb_test "p ((int (*) ()) foo) ()" " = 0"
+
+# Call the function, casting the function result to the correct type.
+gdb_test "p (int) foo ()" " = 0"