Pass void_context_p to parse_expression

An earlier patch pointed out that nothing in GDB sets void_context_p
when parsing an expression.  This patch fixes this omission.

"print" and "call" differ in that the former will print a value that
has void type, while the latter will not.  AdaCore has had a patch for
a long time that uses this distinction to help with overload
resolution.  In particular, in a "call" context, a procedure will be
chosen, while in a "print" context, a zero-argument function will be
chosen instead.

Regression tested on x86-64 Fedora 32.

gdb/ChangeLog
2021-01-08  Tom Tromey  <tromey@adacore.com>

	* parse.c (parse_expression): Add void_context_p parameter.  Use
	parse_exp_in_context.
	* printcmd.c (print_command_1): Change voidprint to bool.  Pass to
	parse_expression.
	(print_command, call_command): Update.
	* expression.h (parse_expression): Add void_context_p parameter.

gdb/testsuite/ChangeLog
2021-01-08  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/voidctx/pck.adb: New file.
	* gdb.ada/voidctx/pck.ads: New file.
	* gdb.ada/voidctx/voidctx.adb: New file.
	* gdb.ada/voidctx.exp: New file.

5 files changed, 128 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index ef3e794..fcca049 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2021-01-08  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/voidctx/pck.adb: New file.
+	* gdb.ada/voidctx/pck.ads: New file.
+	* gdb.ada/voidctx/voidctx.adb: New file.
+	* gdb.ada/voidctx.exp: New file.
+
 2021-01-08  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	PR gdb/27157
diff --git a/gdb/testsuite/gdb.ada/voidctx.exp b/gdb/testsuite/gdb.ada/voidctx.exp
new file mode 100644
index 0000000..c557c1f
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/voidctx.exp
@@ -0,0 +1,40 @@
+# Copyright 2021 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 "ada.exp"
+
+if { [skip_ada_tests] } { return -1 }
+
+standard_ada_testfile voidctx
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/voidctx.adb]
+runto "voidctx.adb:$bp_location"
+
+gdb_test "print pck.proc_count" " = 0" "initial proc_count"
+gdb_test "print pck.func_count" " = 0" "initial func_count"
+
+gdb_test "print DoSomething" " = 42"
+gdb_test "print pck.proc_count" " = 0" "check proc_count 1"
+gdb_test "print pck.func_count" " = 1" "check func_count 1"
+
+gdb_test_no_output "call DoSomething"
+gdb_test "print pck.proc_count" " = 1" "check proc_count 2"
+gdb_test "print pck.func_count" " = 1" "check func_count 2"
diff --git a/gdb/testsuite/gdb.ada/voidctx/pck.adb b/gdb/testsuite/gdb.ada/voidctx/pck.adb
new file mode 100644
index 0000000..bdd76cd
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/voidctx/pck.adb
@@ -0,0 +1,27 @@
+--  Copyright 2021 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/>.
+
+package body Pck is
+   function DoSomething return Integer is
+   begin
+      Func_Count := Func_Count + 1;
+      return 42;
+   end;
+
+   procedure DoSomething is
+   begin
+      Proc_Count := Proc_Count + 1;
+   end;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/voidctx/pck.ads b/gdb/testsuite/gdb.ada/voidctx/pck.ads
new file mode 100644
index 0000000..cf7fe15
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/voidctx/pck.ads
@@ -0,0 +1,23 @@
+--  Copyright 2021 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/>.
+
+package Pck is
+   -- Each count is incremented by the respective DoSomething.
+   Proc_Count : Integer := 0;
+   Func_Count : Integer := 0;
+
+   function DoSomething return Integer;
+   procedure DoSomething;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/voidctx/voidctx.adb b/gdb/testsuite/gdb.ada/voidctx/voidctx.adb
new file mode 100644
index 0000000..f70c7f0
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/voidctx/voidctx.adb
@@ -0,0 +1,31 @@
+--  Copyright 2021 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/>.
+
+with Pck; use Pck;
+procedure Voidctx is
+
+   function DoSomething return Integer is
+   begin
+      return 42;
+   end;
+
+   procedure DoSomething is
+   begin
+      null;
+   end;
+
+begin
+   null;  -- STOP
+end Voidctx;