gdb/fortran: Nested subroutine support

This patch is a rebase and update of the following three patches:

   https://sourceware.org/ml/gdb-patches/2018-11/msg00298.html
   https://sourceware.org/ml/gdb-patches/2018-11/msg00302.html
   https://sourceware.org/ml/gdb-patches/2018-11/msg00301.html

I have merged these together into a single commit as the second patch,
adding scope support to nested subroutines, means that some of the
changes in the first patch are now no longer useful and would have to
be backed out.  The third patch is tightly coupled to the changes in
the second of these patches and I think deserves to live together with
it.

There is an extra change in cp-namespace.c that is new, this resolves
an issue with symbol lookup when placing breakpoints from within
nested subroutines.

There is also an extra test added to this commit 'nested-funcs-2.exp'
that was written by Richard Bunt from ARM, this offers some additional
testing of breakpoints on nested functions.

After this commit it is possible to place breakpoints on nested
Fortran subroutines and functions by using a fully scoped name, for
example, given this simple Fortran program:

    program greeting
      call message
    contains
      subroutine message
        print *, "Hello World"
      end subroutine message
    end program greeting

It is possible to place a breakpoint in 'message' with:

    (gdb) break greeting::message
    Breakpoint 1 at 0x4006c9: file basic.f90, line 5.

What doesn't work with this commit is placing a breakpoint like this:

    (gdb) break message
    Function "message" not defined.

Making this work will come in a later commit.

gdb/ChangeLog:

	* cp-namespace.c (cp_search_static_and_baseclasses): Only search
	for nested static variables when searchin VAR_DOMAIN.
	* dwarf2read.c (add_partial_symbol): Add nested subroutines to the
	global scope, update comment.
	(add_partial_subprogram): Call add_partial_subprogram recursively
	for nested subroutines when processinng Fortran.
	(load_partial_dies): Process the child entities of a subprogram
	when processing Fortran.
	(partial_die_parent_scope): Handle building scope
	for Fortran nested functions.
	(process_die): Record that nested functions have a scope.
	(new_symbol): Always record Fortran subprograms on the global
	symbol list.
	(determine_prefix): How to build the prefix for Fortran
	subprograms.

gdb/testsuite/ChangeLog:

	* gdb.fortran/nested-funcs.exp: Tests for placing breakpoints on
	nested functions.
	* gdb.fortran/nested-funcs.f90: Update expected results.
	* gdb.fortran/nested-funcs-2.exp: New file.
	* gdb.fortran/nested-funcs-2.f90: New file.

gdb/doc/ChangeLog:

	* doc/gdb.texinfo (Fortran Operators): Describe scope operator.

1 files changed, 159 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.fortran/nested-funcs-2.exp b/gdb/testsuite/gdb.fortran/nested-funcs-2.exp
new file mode 100644
index 0000000..4e121cd
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/nested-funcs-2.exp
@@ -0,0 +1,159 @@
+# 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/> .
+
+# Further testing of placing breakpoints in nested subroutines.
+
+if {[skip_fortran_tests]} { return -1 }
+load_lib "fortran.exp"
+
+standard_testfile ".f90"
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} \
+	 ${srcfile} {debug f90}]} {
+    return -1
+}
+
+set int4 [fortran_int4]
+
+# When WITH_SRC_PREFIX_P is true then some symbol references will be
+# prefixed with the filename.  When WITH_NEST_PREFIX_P is true then
+# nested subroutine symbols will be prefixed with their parent
+# subroutine scope.
+proc do_bp_tests {with_src_prefix_p with_nest_prefix_p} {
+    global testfile srcfile
+    global int4
+    global hex
+
+    clean_restart ${testfile}
+
+    if { $with_src_prefix_p } {
+	set src_prefix "${srcfile}:"
+    } else {
+	set src_prefix ""
+    }
+
+    if { $with_nest_prefix_p } {
+	set nest_prefix "contains_keyword::"
+    } else {
+	set nest_prefix ""
+    }
+
+    # Test setting up breakpoints and otherwise examining nested
+    # functions before the program starts.
+    with_test_prefix "before start" {
+	foreach entry \
+	    [list \
+		 [list "increment" "${int4} \\\(${int4}\\\)"] \
+		 [list "increment_program_global" "${int4} \\\(void\\\)"] \
+		 [list "hidden_variable" "void \\\(void\\\)"]] {
+		     set function [lindex $entry 0]
+		     set type [lindex $entry 1]
+
+		     # Currently referencing symbols using 'info',
+		     # 'whatis' and 'ptype' before the program is
+		     # started doesn't work.  This is the same
+		     # behaviour we see in C++ so I don't think this
+		     # is a failure, just a limitation in current GDB.
+		     if { ${with_nest_prefix_p} } {
+			 gdb_test "info symbol ${nest_prefix}${function}" \
+			     "${function} in section .*"
+			 gdb_test "whatis ${nest_prefix}${function}" \
+			     "type = ${type}"
+			 gdb_test "ptype ${nest_prefix}${function}" \
+			     "type = ${type}"
+			 gdb_test "print ${nest_prefix}${function}" \
+			     "{${type}} $hex <contains_keyword::${function}>"
+		     }
+
+		     gdb_breakpoint "${src_prefix}${nest_prefix}${function}"
+		 }
+    }
+
+    # Break on a contained function and run to it.
+    if {![runto ${src_prefix}[gdb_get_line_number "pre_init"]]} then {
+	perror "couldn't run to breakpoint pre_init"
+	continue
+    }
+
+    # Call a contained function.
+    if { ${with_nest_prefix_p} } {
+	gdb_test "call ${nest_prefix}subroutine_to_call()" " called"
+    }
+
+    # Break on another contained function and run to it.
+    gdb_breakpoint "${src_prefix}${nest_prefix}increment"
+    gdb_continue_to_breakpoint "increment" ".*increment = i \\\+ 1"
+    gdb_breakpoint ${src_prefix}[gdb_get_line_number "post_increment"]
+    gdb_continue_to_breakpoint "post_increment"
+
+    # Check arguments and locals report the correct values. 12 is
+    # passed in and 13 is the result after adding 1.
+    gdb_test "info args" "i = 12"
+    gdb_test "info locals" " = 13"
+
+    # Check we can see variables from an outer program scope.
+    gdb_breakpoint ${src_prefix}[gdb_get_line_number "post_increment_global"]
+    gdb_continue_to_breakpoint "post_increment_global" \
+	".*print \\\*, program_i ! post_increment_global"
+    gdb_test "info args" "No arguments." \
+	"no argument subroutine has no arguments"
+    gdb_test "p program_i" " = 7" "printing outer scoped variable"
+
+    # Stepping into a contained subroutine.
+    gdb_breakpoint ${src_prefix}[gdb_get_line_number "pre_step"]
+    gdb_continue_to_breakpoint "pre_step" ".*call step\\\(\\\) ! pre_step"
+    gdb_test "step" \
+	".*print '\\\(A\\\)', \\\"step\\\" ! post_step" \
+	"step into the correct place"
+
+    # Local hides program global.
+    gdb_breakpoint ${src_prefix}[gdb_get_line_number "post_hidden"]
+    gdb_continue_to_breakpoint "post_hidden" \
+	".*print \\\*, program_i ! post_hidden"
+    gdb_test "p program_i" " = 30" "printing hidden global"
+
+    # Check that the methods in the container module still require the
+    # module name as context.
+    gdb_test_no_output "set confirm off"
+    gdb_test "break print_from_module" \
+        "Function \\\"print_from_module\\\" not defined."
+
+    # Check info symbol, whatis and ptype can find information on
+    # these nested functions.
+    foreach entry \
+	[list \
+	     [list "increment" "${int4} \\\(${int4}\\\)"] \
+	     [list "increment_program_global" "${int4} \\\(void\\\)"]] {
+		 set function [lindex $entry 0]
+		 set type [lindex $entry 1]
+		 with_test_prefix $function {
+		     gdb_test "info symbol ${nest_prefix}$function" \
+			 "$function in section .*"
+		     gdb_test "whatis ${nest_prefix}$function" \
+			 "type = ${type}"
+		     gdb_test "ptype ${nest_prefix}$function" \
+			 "type = ${type}"
+		 }
+	     }
+}
+
+foreach_with_prefix src_prefix { 0 1 } {
+    # For now this loop is only run with a value of '1'.  A later
+    # patch will extend this with the value '0', at which point this
+    # comment will be removed.
+    foreach_with_prefix nest_prefix { 1 } {
+	do_bp_tests ${src_prefix} ${nest_prefix}
+    }
+}