Fix bit strides for -fgnat-encodings=minimal

With -fgnat-encodings=minimal, the enum_idx_packed.exp test will fail.
In this test case, we have an array (with dynamic length) of arrays,
and the inner array has a bit stride.  In this situation, the outer
array's bit stride must be updated to account for the entire bit
length of the inner array.

Here, again, some tests must be kfail'd when an older version of GNAT
is in use.

gdb/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* gdbtypes.c (update_static_array_size): Handle bit stride.

gdb/testsuite/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/enum_idx_packed.exp: Test two forms of -fgnat-encodings.

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2020-11-04  Tom Tromey  <tromey@adacore.com>
+
+	* gdbtypes.c (update_static_array_size): Handle bit stride.
+
 2020-11-04  Tom Tromey  <tromey@adacore.com>
 
 	* ada-lang.c (ada_value_struct_elt): Resolve dynamic type.

gdb/gdbtypes.c

@@ -1241,6 +1241,20 @@ update_static_array_size (struct type *type)
 	TYPE_LENGTH (type) =
 	  TYPE_LENGTH (element_type) * (high_bound - low_bound + 1);
 
+      /* If this array's element is itself an array with a bit stride,
+	 then we want to update this array's bit stride to reflect the
+	 size of the sub-array.  Otherwise, we'll end up using the
+	 wrong size when trying to find elements of the outer
+	 array.  */
+      if (element_type->code () == TYPE_CODE_ARRAY
+	  && TYPE_LENGTH (element_type) != 0
+	  && TYPE_FIELD_BITSIZE (element_type, 0) != 0
+	  && get_array_bounds (element_type, &low_bound, &high_bound) >= 0
+	  && high_bound >= low_bound)
+	TYPE_FIELD_BITSIZE (type, 0)
+	  = ((high_bound - low_bound + 1)
+	     * TYPE_FIELD_BITSIZE (element_type, 0));
+
       return true;
     }
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2020-11-04  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/enum_idx_packed.exp: Test two forms of -fgnat-encodings.
+
 2020-11-04  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.ada/set_pckd_arr_elt.exp: Also test

gdb/testsuite/gdb.ada/enum_idx_packed.exp

@@ -19,12 +19,22 @@ if { [skip_ada_tests] } { return -1 }
 
 standard_ada_testfile foo
 
-if {[gdb_compile_ada "${srcfile}" "${binfile}" executable {debug}] != ""} {
+foreach_with_prefix scenario {all minimal} {
+    set flags [list debug additional_flags=-fgnat-encodings=$scenario]
+
+    if {[gdb_compile_ada "${srcfile}" "${binfile}" executable $flags] != ""} {
 	return -1
     }
 
     clean_restart ${testfile}
 
+    # GNAT >= 11.0 has the needed fix here.
+    if {$scenario == "minimal" && ![test_compiler_info {gcc-1[1-9]-*}]} {
+	set old_compiler 1
+    } else {
+	set old_compiler 0
+    }
+
     set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
     runto "foo.adb:$bp_location"
 
@@ -52,19 +62,38 @@ gdb_test "print cold'first" " = green"
     # Note the bounds values are still not correctly displayed.  So we get
     # the enum equivalent of "1 .. 0" (empty range) as the array ranges.
     # Accept that for now.
+    # GNAT >= 11.0 has the needed fix here.
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "ptype small" \
 	"array \\(red \\.\\. green\\) of boolean <packed: 1-bit elements>"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print small" " = \\(red => false, true\\)"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print small'first" " = red"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "ptype multi" \
 	"array \\(red \\.\\. green, low .. medium\\) of boolean <packed: 1-bit elements>"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print multi" \
 	" = \\(red => \\(low => true, false\\), \\(low => true, false\\)\\)"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print multi'first" " = red"
 
     set base "\\(true, false, true, false, true, false, true, false, true, false\\)"
@@ -77,6 +106,16 @@ foreach x {1 2 3 4 5 6 7} {
     }
     append matrix "\\)"
 
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print multi_multi" " = \\($matrix, $matrix\\)"
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print multi_multi(1,3)" " = $base"
+    if {$old_compiler} {
+	setup_kfail "minimal encodings" *-*-*
+    }
     gdb_test "print multi_multi(2)" " = $matrix"
+}