[binutils-gdb] gdb/testsuite: adjust gdb.python/flexible-array-member.exp expected pattern

[binutils-gdb] gdb/testsuite: adjust gdb.python/flexible-array-member.exp expected pattern

[Simon Marchi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=858c8f2c1b900258c44cebe2798ca0271100a33d

commit 858c8f2c1b900258c44cebe2798ca0271100a33d
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Tue May 4 11:20:09 2021 -0400

    gdb/testsuite: adjust gdb.python/flexible-array-member.exp expected pattern
    
    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:
---
 gdb/testsuite/ChangeLog                            |  6 ++++++
 gdb/testsuite/gdb.python/flexible-array-member.exp | 16 ++++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 16c0df13fa2..32eba3663a7 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2021-05-04  Simon Marchi  <simon.marchi@efficios.com>
+
+	* gdb.python/flexible-array-member.exp: Adjust expected range
+	value for member declared with 0 size.  Test accessing range
+	tuple through range type.
+
 2021-05-03  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	PR testsuite/27788
diff --git a/gdb/testsuite/gdb.python/flexible-array-member.exp b/gdb/testsuite/gdb.python/flexible-array-member.exp
index 349670cb7e7..eab94e8a412 100644
--- 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)\\)"