From FEDORA_PATCHES Mon Sep 17 00:00:00 2001

From: Simon Marchi <simon.marchi@efficios.com>

Date: Tue, 4 May 2021 11:20:09 -0400

Subject: gdb-flexible-array-member-expected-pattern.patch

;; Backport "adjust gdb.python/flexible-array-member.exp expected pattern"

;; (Simon Marchi)

The `Type.range ()` tests in gdb.python/flexible-array-member.exp pass

when the test is compiled with gcc 9 or later, but not with gcc 8 or

earlier:

    $ make check TESTS="gdb.python/flexible-array-member.exp" RUNTESTFLAGS="CC_FOR_TARGET='gcc-8'"

    python print(zs['items'].type.range())^M

    (0, 0)^M

    (gdb) FAIL: gdb.python/flexible-array-member.exp: python print(zs['items'].type.range())

    python print(zso['items'].type.range())^M

    (0, 0)^M

    (gdb) FAIL: gdb.python/flexible-array-member.exp: python print(zso['items'].type.range())

The value that we get for the upper bound of a flexible array member

declared with a "0" size is 0 with gcc <= 8 and is -1 for gcc >= 9.

This is due to different debug info.  For this member, gcc 8 does:

    0x000000d5:   DW_TAG_array_type

                    DW_AT_type [DW_FORM_ref4]       (0x00000034 "int")

                    DW_AT_sibling [DW_FORM_ref4]    (0x000000e4)

    0x000000de:     DW_TAG_subrange_type

                      DW_AT_type [DW_FORM_ref4]     (0x0000002d "long unsigned int")

For the same type, gcc 9 does:

    0x000000d5:   DW_TAG_array_type

                    DW_AT_type [DW_FORM_ref4]       (0x00000034 "int")

                    DW_AT_sibling [DW_FORM_ref4]    (0x000000e5)

    0x000000de:     DW_TAG_subrange_type

                      DW_AT_type [DW_FORM_ref4]     (0x0000002d "long unsigned int")

                      DW_AT_count [DW_FORM_data1]   (0x00)

Ideally, GDB would present a consistent and documented value for an

array member declared with size 0, regardless of how the debug info

looks like.  But for now, just change the test to accept the two

values, to get rid of the failure and make the test in sync

I also realized (by looking at the py-type.exp test) that calling the

fields method on an array type yields one field representing the "index"

of the array.  The type of that field is of type range

(gdb.TYPE_CODE_RANGE).  When calling `.range()` on that range type, it

yields the same range tuple as when calling `.range()` on the array type

itself.  For completeness, add some tests to access the range tuple

through that range type as well.

gdb/testsuite/ChangeLog:

	* gdb.python/flexible-array-member.exp: Adjust expected range

	value for member declared with 0 size.  Test accessing range

	tuple through range type.

Change-Id: Ie4e06d99fe9315527f04577888f48284d649ca4c

diff --git a/gdb/testsuite/gdb.python/flexible-array-member.exp b/gdb/testsuite/gdb.python/flexible-array-member.exp

--- a/gdb/testsuite/gdb.python/flexible-array-member.exp

+++ b/gdb/testsuite/gdb.python/flexible-array-member.exp

@@ -76,9 +76,17 @@ gdb_test "python print(zso\['items'\] == zso\['items'\]\[0\].address)" "True"

 gdb_test "python print(zso\['items'\]\[0\].address + 1 == zso\['items'\]\[1\].address)" "True"

 # Verify the range attribute.  It looks a bit inconsistent that the high bound

-# is sometimes 0, sometimes -1, but that's what GDB produces today, so that's

-# what we test.

+# is sometimes 0, sometimes -1.  It depends on the way the flexible array

+# member is specified and on the compiler version (the debug info is

+# different).  But that's what GDB produces today, so that's what we test.

 gdb_test "python print(ns\['items'\].type.range())" "\\(0, 0\\)"

-gdb_test "python print(zs\['items'\].type.range())" "\\(0, -1\\)"

-gdb_test "python print(zso\['items'\].type.range())" "\\(0, -1\\)"

+gdb_test "python print(zs\['items'\].type.range())" "\\(0, (0|-1)\\)"

+gdb_test "python print(zso\['items'\].type.range())" "\\(0, (0|-1)\\)"

+

+# Test the same thing, but going explicitly through the array index's range

+# type.

+

+gdb_test "python print(ns\['items'\].type.fields()\[0\].type.range())" "\\(0, 0\\)"

+gdb_test "python print(zs\['items'\].type.fields()\[0\].type.range())" "\\(0, (0|-1)\\)"

+gdb_test "python print(zso\['items'\].type.fields()\[0\].type.range())" "\\(0, (0|-1)\\)"