[PATCH 1/2] gdb/fortran: resolve dynamic types when readjusting after an indirection

[Andrew Burgess <andrew.burgess@embecosm.com>]

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/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/26139
	* gdb.fortran/class-allocatable-array.exp: New file.
	* gdb.fortran/class-allocatable-array.f90: New file.
---
 gdb/ChangeLog                                 | 11 ++++
 gdb/testsuite/ChangeLog                       |  6 +++
 .../gdb.fortran/class-allocatable-array.exp   | 43 +++++++++++++++
 .../gdb.fortran/class-allocatable-array.f90   | 54 +++++++++++++++++++
 gdb/valops.c                                  | 24 +++++----
 gdb/value.c                                   | 23 +++++---
 gdb/value.h                                   |  7 ++-
 7 files changed, 149 insertions(+), 19 deletions(-)
 create mode 100644 gdb/testsuite/gdb.fortran/class-allocatable-array.exp
 create mode 100644 gdb/testsuite/gdb.fortran/class-allocatable-array.f90

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 00000000000..9475ba3b393
--- /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\\) \\)"
diff --git a/gdb/testsuite/gdb.fortran/class-allocatable-array.f90 b/gdb/testsuite/gdb.fortran/class-allocatable-array.f90
new file mode 100644
index 00000000000..26d5fab0355
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/class-allocatable-array.f90
@@ -0,0 +1,54 @@
+! 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/>.
+
+module test_module
+  type test_type
+     integer a
+     real, allocatable :: b (:, :)
+   contains
+     procedure :: test_proc
+  end type test_type
+
+contains
+
+  subroutine test_proc (this)
+    class(test_type), intent (inout) :: this
+    allocate (this%b (3, 2))
+    call fill_array_2d (this%b)
+    print *, ""		! Break Here
+  contains
+    ! Helper subroutine to fill 2-dimensional array with unique
+    ! values.
+    subroutine fill_array_2d (array)
+      real, dimension (:,:) :: array
+      real :: counter
+
+      counter = 1.0
+      do i=LBOUND (array, 2), UBOUND (array, 2), 1
+         do j=LBOUND (array, 1), UBOUND (array, 1), 1
+            array (j,i) = counter
+            counter = counter + 1
+         end do
+      end do
+    end subroutine fill_array_2d
+  end subroutine test_proc
+end module
+
+program test
+  use test_module
+  implicit none
+  type(test_type) :: t
+  call t%test_proc ()
+end program test
diff --git a/gdb/valops.c b/gdb/valops.c
index afdb429dc37..61625977f00 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1559,20 +1559,24 @@ value_ind (struct value *arg1)
       enc_type = check_typedef (value_enclosing_type (arg1));
       enc_type = TYPE_TARGET_TYPE (enc_type);
 
+      CORE_ADDR base_addr;
       if (check_typedef (enc_type)->code () == TYPE_CODE_FUNC
 	  || check_typedef (enc_type)->code () == TYPE_CODE_METHOD)
-	/* For functions, go through find_function_addr, which knows
-	   how to handle function descriptors.  */
-	arg2 = value_at_lazy (enc_type, 
-			      find_function_addr (arg1, NULL));
+	{
+	  /* For functions, go through find_function_addr, which knows
+	     how to handle function descriptors.  */
+	  base_addr = find_function_addr (arg1, NULL);
+	}
       else
-	/* Retrieve the enclosing object pointed to.  */
-	arg2 = value_at_lazy (enc_type, 
-			      (value_as_address (arg1)
-			       - value_pointed_to_offset (arg1)));
-
+	{
+	  /* Retrieve the enclosing object pointed to.  */
+	  base_addr = (value_as_address (arg1)
+		       - value_pointed_to_offset (arg1));
+	}
+      arg2 = value_at_lazy (enc_type, base_addr);
       enc_type = value_type (arg2);
-      return readjust_indirect_value_type (arg2, enc_type, base_type, arg1);
+      return readjust_indirect_value_type (arg2, enc_type, base_type,
+					   arg1, base_addr);
     }
 
   error (_("Attempt to take contents of a non-pointer value."));
diff --git a/gdb/value.c b/gdb/value.c
index 97a099ddbd3..826cd35b43f 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -3618,10 +3618,20 @@ coerce_ref_if_computed (const struct value *arg)
 struct value *
 readjust_indirect_value_type (struct value *value, struct type *enc_type,
 			      const struct type *original_type,
-			      const struct value *original_value)
+			      struct value *original_value,
+			      CORE_ADDR original_value_address)
 {
+  gdb_assert (original_type->code () == TYPE_CODE_PTR
+	      || TYPE_IS_REFERENCE (original_type));
+
+  struct type *original_target_type = TYPE_TARGET_TYPE (original_type);
+  gdb::array_view<const gdb_byte> view;
+  struct type *resolved_original_target_type
+    = resolve_dynamic_type (original_target_type, view,
+			    original_value_address);
+
   /* Re-adjust type.  */
-  deprecated_set_value_type (value, TYPE_TARGET_TYPE (original_type));
+  deprecated_set_value_type (value, resolved_original_target_type);
 
   /* Add embedding info.  */
   set_value_enclosing_type (value, enc_type);
@@ -3648,12 +3658,11 @@ coerce_ref (struct value *arg)
   enc_type = check_typedef (value_enclosing_type (arg));
   enc_type = TYPE_TARGET_TYPE (enc_type);
 
-  retval = value_at_lazy (enc_type,
-                          unpack_pointer (value_type (arg),
-                                          value_contents (arg)));
+  CORE_ADDR addr = unpack_pointer (value_type (arg), value_contents (arg));
+  retval = value_at_lazy (enc_type, addr);
   enc_type = value_type (retval);
-  return readjust_indirect_value_type (retval, enc_type,
-                                       value_type_arg_tmp, arg);
+  return readjust_indirect_value_type (retval, enc_type, value_type_arg_tmp,
+				       arg, addr);
 }
 
 struct value *
diff --git a/gdb/value.h b/gdb/value.h
index 70c3d5667ae..12e4a13e3e4 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -488,7 +488,9 @@ extern struct value *coerce_ref_if_computed (const struct value *arg);
 
 /* Setup a new value type and enclosing value type for dereferenced value VALUE.
    ENC_TYPE is the new enclosing type that should be set.  ORIGINAL_TYPE and
-   ORIGINAL_VAL are the type and value of the original reference or pointer.
+   ORIGINAL_VAL are the type and value of the original reference or
+   pointer.  ORIGINAL_VALUE_ADDRESS is the address within VALUE, that is
+   the address that was dereferenced.
 
    Note, that VALUE is modified by this function.
 
@@ -497,7 +499,8 @@ extern struct value *coerce_ref_if_computed (const struct value *arg);
 extern struct value * readjust_indirect_value_type (struct value *value,
 						    struct type *enc_type,
 						    const struct type *original_type,
-						    const struct value *original_val);
+						    struct value *original_val,
+						    CORE_ADDR original_value_address);
 
 /* Convert a REF to the object referenced.  */
 
-- 
2.25.4