Fix crash in "finish"

PR gdb/28155 notes a crash in "finish" that occurs with a particular
source file compiled by clang.

The bug is the typical gdb problem of a missing call to check_typedef.
clang emits a function whose return type is a typedef to void.
get_return_value asserts that the return type is not void, but the
callers were not using check_typedef first.

gdb/ChangeLog
2019-01-06  Tom Tromey  <tom@tromey.com>

	PR gdb/28155:
	* python/py-finishbreakpoint.c (bpfinishpy_init): Use
	check_typedef.
	* infcmd.c (finish_command_fsm_should_stop): Use check_typedef.
	(print_return_value): Likewise.

gdb/testsuite/ChangeLog
2019-01-06  Tom Tromey  <tom@tromey.com>

	PR gdb/28155:
	* gdb.dwarf2/typedef-void-finish.exp: New file.

1 files changed, 102 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.dwarf2/typedef-void-finish.exp b/gdb/testsuite/gdb.dwarf2/typedef-void-finish.exp
new file mode 100644
index 00000000000..633409db51c
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/typedef-void-finish.exp
@@ -0,0 +1,102 @@
+# Copyright 2019 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/>.
+
+# PR gdb/21855 concerns a crash in "finish" where the function's
+# return type is a typedef of void.
+
+load_lib dwarf.exp
+load_lib gdb-python.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile void-type.c typedef-void-finish.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcdir subdir srcfile
+
+    set func_result [function_range func ${srcdir}/${subdir}/${srcfile}]
+    set func_start [lindex $func_result 0]
+    set func_length [lindex $func_result 1]
+
+    set main_result [function_range main ${srcdir}/${subdir}/${srcfile}]
+    set main_start [lindex $main_result 0]
+    set main_length [lindex $main_result 1]
+
+    cu {} {
+	DW_TAG_compile_unit {
+	        {DW_AT_producer "GNU C 8.1"}
+                {DW_AT_language @DW_LANG_C}
+                {DW_AT_name     void-type.c}
+                {DW_AT_comp_dir /tmp}
+        } {
+	    declare_labels main_type void_typedef
+
+	    main_type: DW_TAG_base_type {
+		{DW_AT_byte_size 4 DW_FORM_sdata}
+		{DW_AT_encoding  @DW_ATE_signed}
+	    }
+
+	    void_typedef: DW_TAG_typedef {
+		{name foo}
+	    }
+
+            DW_TAG_subprogram {
+                {name func}
+                {low_pc $func_start addr}
+                {high_pc "$func_start + $func_length" addr}
+                {type :$void_typedef}
+	    }
+            DW_TAG_subprogram {
+                {name main}
+                {low_pc $main_start addr}
+                {high_pc "$main_start + $main_length" addr}
+                {type :$main_type}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+if {![runto_main]} {
+    return -1
+}
+
+gdb_test "break func" "Breakpoint .*" \
+    "set breakpoint in func"
+gdb_continue_to_breakpoint "continue to func"
+
+set skip_python [skip_python_tests]
+if {!$skip_python} {
+    gdb_test "python finishbp = gdb.FinishBreakpoint()" \
+	"Temporary breakpoint.*" "set FinishBreakpoint"
+}
+
+gdb_test "finish" [multi_line \
+		       "Run till exit from #0  $hex in func \\\(\\\)" \
+		       ".*$hex in main \\\(\\\)"]
+
+if {!$skip_python} {
+    gdb_test "python print (finishbp.return_value)" "None" \
+	"check that return_value is None"
+}