gdb/fortran: resolve dynamic types when readjusting after an indirection

After dereferencing a pointer (in value_ind) or following a
reference (in coerce_ref) we call readjust_indirect_value_type to
"fixup" the type of the resulting value object.

This fixup handles cases relating to the type of the resulting object
being different (a sub-class) of the original pointers target type.

If we encounter a pointer to a dynamic type then after dereferencing a
pointer (in value_ind) the type of the object created will have had
its dynamic type resolved.  However, in readjust_indirect_value_type,
we use the target type of the original pointer to "fixup" the type of
the resulting value.  In this case, the target type will be a dynamic
type, so the resulting value object, once again has a dynamic type.

This then triggers an assertion later within GDB.

The solution I propose here is that we call resolve_dynamic_type on
the pointer's target type (within readjust_indirect_value_type) so
that the resulting value is not converted back to a dynamic type.

The test case is based on the original test in the bug report.

gdb/ChangeLog:

	PR fortran/23051
	PR fortran/26139
	* valops.c (value_ind): Pass address to
	readjust_indirect_value_type.
	* value.c (readjust_indirect_value_type): Make parameter
	non-const, and add extra address parameter.  Resolve original type
	before using it.
	* value.h (readjust_indirect_value_type): Update function
	signature and comment.

gdb/testsuite/ChangeLog:

	PR fortran/23051
	PR fortran/26139
	* gdb.fortran/class-allocatable-array.exp: New file.
	* gdb.fortran/class-allocatable-array.f90: New file.
	* gdb.fortran/pointer-to-pointer.exp: New file.
	* gdb.fortran/pointer-to-pointer.f90: New file.

1 files changed, 43 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.fortran/class-allocatable-array.exp b/gdb/testsuite/gdb.fortran/class-allocatable-array.exp
new file mode 100644
index 0000000..9475ba3
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/class-allocatable-array.exp
@@ -0,0 +1,43 @@
+# Copyright 2020 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 that GDB can print an allocatable array that is a data field
+# within a class like type.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile ".f90"
+load_lib fortran.exp
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} \
+	 {debug f90}]} {
+    return -1
+}
+
+if ![fortran_runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break Here"]
+gdb_continue_to_breakpoint "Break Here"
+
+# If this first test fails then the Fortran compiler being used uses
+# different names, or maybe a completely different approach, for
+# representing class like structures.  The following tests are
+# cetainly going to fail.
+gdb_test "print this" " = \\( _data = \[^\r\n\]+, _vptr = \[^\r\n\]+\\)"
+gdb_test "print this%_data" " = \\(PTR TO -> \\( Type test_type \\)\\) \[^\r\n\]+"
+gdb_test "print this%_data%b" " = \\(\\( 1, 2, 3\\) \\( 4, 5, 6\\) \\)"