gdb and binutils branch master updated. 8776cfe971c3917e924c669140746735f94439f4

[brobecke at sourceware dot org]

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=8776cfe971c3917e924c669140746735f94439f4

commit 8776cfe971c3917e924c669140746735f94439f4
Author: Joel Brobecker <brobecker@adacore.com>
Date:   Thu Mar 20 07:43:08 2014 -0700

    [varobj] false type-changed status for reference to Ada array
    
    Given the following variable...
    
       BT : Bounded := New_Bounded (Low => 1, High => 3);
    
    ... where type Bounded is defined as a simple unconstrained array:
    
       type Bounded is array (Integer range <>) of Integer;
    
    Creating a varobj for that variable, and immediately asking for
    varobj updates, GDB says that our varobj changed types!
    
        (gdb)
        -var-create bt * bt
        ^done,name="bt",numchild="3",value="[3]",type="<ref> array (1 .. 3) of integer",has_more="0"
        (gdb)
        -var-update 1 *
        ^done,changelist=[{name="bt",value="[3]",in_scope="true",type_changed="true",new_type="<ref> array (1 .. 3) of integer",new_num_children="3",has_more="0"}]
    
    The expected output for the -var-update command is, in this case:
    
        (gdb)
        -var-update 1 *
        ^done,changelist=[]
    
    The problem occurs because the ada-varobj module does not handle
    references, and while the references gets stripped when the varobj
    gets created, it doesn't when computing varobj updates.
    
    More specifically, when creating the varobj, varobj_create creates
    a new value which is a reference to a TYPE_CODE_ARRAY. It then calls
    install_new_value which calls coerce_ref with the following comment:
    
        /* We are not interested in the address of references, and given
           that in C++ a reference is not rebindable, it cannot
           meaningfully change.  So, get hold of the real value.  */
        if (value)
          value = coerce_ref (value);
    
    This leaves the varobj's type component still a ref, while
    the varobj's value is now our array, without the ref. This explains
    why the "value" field in the varobj indicates an array with 3 elements
    "[3]" while the "type" field shows a ref to an array. Generally
    speaking, most users have said that showing the ref was a useful
    piece of information, so this patch is not touching this part.
    
    Next, when the user issues the -var-update request, varobj_update
    calls value_of_root to compute the varobj's new value as well as
    determine whether the value's type has changed or not. What happens
    in a nutshell is that it calls value_of_root_1 (which re-evaluates
    the expression and returns the corresponding new value), finds that
    the new value is not NULL, and thus asks whether it has mutated:
    
        else if (varobj_value_has_mutated (var, value, value_type (value)))
    
    This then indirectly delegates the determination to the language-specific
    callback, which fails, because it does not handle references.
    
    This patch fixes the issue by adjusting varobj_value_has_mutated to
    expect references, and strip them when seen. This allows the various
    language-specific implementations to remain unaware of references.
    
    gdb/ChangeLog:
    
            * varobj.c (varobj_value_has_mutated): If NEW_VALUE is
            a reference, strip the reference layer before calling
            the lang_ops value_has_mutated callback.
    
    gdb/testsuite/ChangeLog:
    
            * gdb.ada/mi_dyn_arr: New testcase.

-----------------------------------------------------------------------

Summary of changes:
 gdb/ChangeLog                            |    6 +++
 gdb/testsuite/ChangeLog                  |    4 ++
 gdb/testsuite/gdb.ada/mi_dyn_arr.exp     |   52 ++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.ada/mi_dyn_arr/foo.adb |   24 ++++++++++++++
 gdb/testsuite/gdb.ada/mi_dyn_arr/pck.adb |   30 +++++++++++++++++
 gdb/testsuite/gdb.ada/mi_dyn_arr/pck.ads |   21 ++++++++++++
 gdb/varobj.c                             |   11 ++++++-
 7 files changed, 147 insertions(+), 1 deletions(-)
 create mode 100644 gdb/testsuite/gdb.ada/mi_dyn_arr.exp
 create mode 100644 gdb/testsuite/gdb.ada/mi_dyn_arr/foo.adb
 create mode 100644 gdb/testsuite/gdb.ada/mi_dyn_arr/pck.adb
 create mode 100644 gdb/testsuite/gdb.ada/mi_dyn_arr/pck.ads


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