Use GCC5/DWARF5 DW_AT_noreturn to mark functions that don't return normally.

Add a flag field is_noreturn to struct func_type. Make calling_convention
a small bit field to not increase the size of the struct. Set is_noreturn
if the new GCC5/DWARF5 DW_AT_noreturn is set on a DW_TAG_subprogram.
Use this information to warn the user before doing a finish or return from
a function that does not return normally to its caller.

(gdb) finish
warning: Function endless does not return normally.
Try to finish anyway? (y or n)

(gdb) return
warning: Function does not return normally to caller.
Make endless return now? (y or n)

gdb/ChangeLog

	* dwarf2read.c (read_subroutine_type): Set TYPE_NO_RETURN from
	DW_AT_noreturn.
	* gdbtypes.h (struct func_type): Add is_noreturn field flag. Make
	calling_convention an 8 bit bit field.
	(TYPE_NO_RETURN): New macro.
	* infcmd.c (finish_command): Query if function does not return
	normally.
	* stack.c (return_command): Likewise.

gdb/testsuite/ChangeLog

	* gdb.base/noreturn-return.c: New file.
	* gdb.base/noreturn-return.exp: New file.
	* gdb.base/noreturn-finish.c: New file.
	* gdb.base/noreturn-finish.exp: New file.

include/ChangeLog

	* dwarf2.def (DW_AT_noreturn): New DWARF5 attribute.

The dwarf2.h addition and the code to emit the new attribute is already in
the gcc tree.

5 files changed, 171 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 1a17ba4..5b53cdd 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2015-01-15  Mark Wielaard  <mjw@redhat.com>
+
+	* gdb.base/noreturn-return.c: New file.
+	* gdb.base/noreturn-return.exp: New file.
+	* gdb.base/noreturn-finish.c: New file.
+	* gdb.base/noreturn-finish.exp: New file.
+
 2015-01-23  Pedro Alves  <palves@redhat.com>
 
 	* gdb.threads/continue-pending-after-query.c: New file.
diff --git a/gdb/testsuite/gdb.base/noreturn-finish.c b/gdb/testsuite/gdb.base/noreturn-finish.c
new file mode 100644
index 0000000..3ec48cd
--- /dev/null
+++ b/gdb/testsuite/gdb.base/noreturn-finish.c
@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+#include <stdlib.h>
+
+void __attribute__((noreturn))
+noreturn_func (void)
+{
+  abort ();
+}
+
+int
+main (void)
+{
+  noreturn_func ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/noreturn-finish.exp b/gdb/testsuite/gdb.base/noreturn-finish.exp
new file mode 100644
index 0000000..a2ae0db
--- /dev/null
+++ b/gdb/testsuite/gdb.base/noreturn-finish.exp
@@ -0,0 +1,51 @@
+# Copyright 2015 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/>.
+
+standard_testfile
+
+if [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} {debug}] {
+    return -1
+}
+
+proc noreturn_finish_test { } {
+    global gdb_prompt
+
+    if { ! [ runto_main ] } then {
+	untested ${testfile}.exp
+	return -1
+    }
+
+    gdb_breakpoint "noreturn_func"
+    gdb_continue_to_breakpoint "noreturn_func"
+
+    set test "cancel finish from noreturn_func"
+    gdb_test_multiple "finish" $test {
+	-re "warning: Function noreturn_func does not return normally" {
+	    verbose -log "saw warning"
+	    exp_continue
+	}
+	-re "Try to finish anyway.*y or n.* $" {
+	    send_gdb "n\n"
+	    exp_continue
+	}
+	-re ".*$gdb_prompt $" {
+	    pass $test
+	}
+   }
+}
+
+clean_restart ${binfile}
+
+noreturn_finish_test
diff --git a/gdb/testsuite/gdb.base/noreturn-return.c b/gdb/testsuite/gdb.base/noreturn-return.c
new file mode 100644
index 0000000..3ec48cd
--- /dev/null
+++ b/gdb/testsuite/gdb.base/noreturn-return.c
@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+#include <stdlib.h>
+
+void __attribute__((noreturn))
+noreturn_func (void)
+{
+  abort ();
+}
+
+int
+main (void)
+{
+  noreturn_func ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/noreturn-return.exp b/gdb/testsuite/gdb.base/noreturn-return.exp
new file mode 100644
index 0000000..8a64a3e
--- /dev/null
+++ b/gdb/testsuite/gdb.base/noreturn-return.exp
@@ -0,0 +1,51 @@
+# Copyright 2015 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/>.
+
+standard_testfile
+
+if [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} {debug}] {
+    return -1
+}
+
+proc noreturn_test { } {
+    global gdb_prompt
+
+    if { ! [ runto_main ] } then {
+	untested ${testfile}.exp
+	return -1
+    }
+
+    gdb_breakpoint "noreturn_func"
+    gdb_continue_to_breakpoint "noreturn_func"
+
+    set test "cancel return from noreturn_func"
+    gdb_test_multiple "return" $test {
+	-re "warning: Function does not return normally to caller" {
+	    verbose -log "saw warning"
+	    exp_continue
+	}
+	-re "Make noreturn_func return now.*y or n. $" {
+	    send_gdb "n\n"
+	    exp_continue
+	}
+	-re "Not confirmed.*$gdb_prompt $" {
+	    pass $test
+	}
+   }
+}
+
+clean_restart ${binfile}
+
+noreturn_test