Fix classification of `module.type' in D lexer.

The two-tier lexer in gdb/d-exp.y, which resolves fully qualified names
missed a case where `module.type' was not being classified as one token.
And so when the grammar takes over, it matched the remaining tokens
against the rule `TypeExp . IdentifierExp', where we were expecting to
instead match cast expression `( TypeExp ) UnaryExpression'.

Adding a case for TYPE_CODE_MODULE in type_aggregate_p means that
classify_inner_name will get a chance to lookup the symbol.

This was noticed when using `watch -l', and got the rather confusing
response:

    A syntax error in expression, near `) 0x0add4e55'.

So it's been included in the testsuite, along with another test that
does effectively the same expression, but explicitly.

gdb/ChangeLog:

	* d-exp.y (type_aggregate_p): Treat TYPE_CODE_MODULE as being
	aggregate-like.

gdb/testsuite/ChangeLog:

	* gdb.dlang/watch-loc.c: New file.
	* gdb.dlang/watch-loc.exp: New file.

gdb/d-exp.y

@@ -648,6 +648,7 @@ type_aggregate_p (struct type *type)
 {
   return (TYPE_CODE (type) == TYPE_CODE_STRUCT
 	  || TYPE_CODE (type) == TYPE_CODE_UNION
+	  || TYPE_CODE (type) == TYPE_CODE_MODULE
 	  || (TYPE_CODE (type) == TYPE_CODE_ENUM
 	      && TYPE_DECLARED_CLASS (type)));
 }

gdb/testsuite/gdb.dlang/watch-loc.c

@@ -0,0 +1,36 @@
+/* Copyright 2017 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/>.  */
+
+
+/* DWARF will describe these contents as being inside a D module.  */
+
+typedef struct tstruct
+{
+} tstruct;
+
+tstruct my_data;
+
+int _Dmain (void)
+{
+  asm ("_Dmain_label: .globl _Dmain_label");
+  return 0;
+}
+
+int
+main (void)
+{
+  return _Dmain ();
+}
+

gdb/testsuite/gdb.dlang/watch-loc.exp

@@ -0,0 +1,83 @@
+# Copyright (C) 2017 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/>.
+
+# Test symbol lookup when there are multiple circular imports.
+
+load_lib "d-support.exp"
+load_lib "dwarf.exp"
+
+if { [skip_d_tests] } { return -1 }
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile watch-loc.c watch-loc-dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcdir subdir srcfile
+
+    cu {} {
+	compile_unit {
+	    {language @DW_LANG_D}
+	} {
+	    declare_labels watch_module_label watch_struct_label
+
+	    watch_module_label: module {
+		{name watch}
+	    } {
+		watch_struct_label: structure_type {
+		    {name tstruct}
+		    {byte_size 1 data1}
+		}
+
+		tag_variable {
+		    {name my_data}
+		    {type :$watch_struct_label}
+		    {location {
+			addr [gdb_target_symbol my_data]
+		    } SPECIAL_expr}
+		    {external 1 flag}
+		}
+
+		subprogram {
+		    {MACRO_AT_func { "_Dmain" "${srcdir}/${subdir}/${srcfile}" }}
+		    {external 1 flag_present}
+		}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+          [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+gdb_test_no_output "set language d"
+
+if {![runto "_Dmain"]} {
+    return -1
+}
+
+# watch -l will rewrite the expression to "*(watch.tstruct *) 0x12345",
+# this should not cause syntax error in the cast expression.
+gdb_test "watch -l my_data" ".*atchpoint \[0-9\]+: -location my_data"
+
+# Same test as above, but done explicitly.
+gdb_test "print *(watch.tstruct *) &my_data" "{<No data fields>}"