Put pretty-printers to_string output in varobj result

PR mi/11335 points out that an MI varobj will not display the result
of a pretty-printer's "to_string" method.  Instead, it always shows
"{...}".

This does not seem very useful, and there have been multiple
complaints about it over the years.  This patch changes varobj to emit
this string when possible, and updates the test suite.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=11335

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 6c811b8be2e548c4492c99a26b67f2da64173109..e8e2c718e4544b1581e656710ec6d05ad70e284b 100644 (file)
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -34523,8 +34523,9 @@ reliable for a dynamic varobj.  Instead, you must examine the
 
 @item value
 The varobj's scalar value.  For a varobj whose type is some sort of
-aggregate (e.g., a @code{struct}), or for a dynamic varobj, this value
-will not be interesting.
+aggregate (e.g., a @code{struct}), this value will not be interesting.
+For a dynamic varobj, this value comes directly from the Python
+pretty-printer object's @code{to_string} method.
 
 @item type
 The varobj's type.  This is a string representation of the type, as

diff --git a/gdb/testsuite/gdb.python/py-mi.exp b/gdb/testsuite/gdb.python/py-mi.exp
index a7b7a5ffcd33434a80d9c8e899b28d0902d47a5e..97b8a42f71534b5ecc4670bbf16c052d8066579b 100644 (file)
--- a/gdb/testsuite/gdb.python/py-mi.exp
+++ b/gdb/testsuite/gdb.python/py-mi.exp
@@ -91,7 +91,7 @@ mi_gdb_test "-var-update string" \
 with_test_prefix "varobj container" {
     # The "elements" field of "c" is still empty, so the attribute
     # "has_more" is expected to be zero.
-    mi_create_dynamic_varobj container c 0 \
+    mi_create_dynamic_varobj container c "container .* with 0 elements" 0 \
        "create container varobj"
 
     mi_list_varobj_children container {
@@ -207,7 +207,7 @@ mi_next "next over update 5"
 
 # Regression test: examine an object that has no children, then update
 # it to ensure that we don't print the children.
-mi_create_dynamic_varobj container2 c2 0 \
+mi_create_dynamic_varobj container2 c2 "container .* with 0 elements" 0 \
   "create second container varobj"
 
 mi_gdb_test "-var-update container2" \
@@ -228,7 +228,7 @@ mi_continue_to_line \
     [gdb_get_line_number {MI outer breakpoint here} ${srcfile}] \
     "step to first outer breakpoint"
 
-mi_create_dynamic_varobj outer outer 1 \
+mi_create_dynamic_varobj outer outer "x = 0" 1 \
   "create outer varobj"
 
 mi_list_varobj_children outer {
@@ -259,7 +259,7 @@ mi_continue_to_line \
     "step to second outer breakpoint"
 
 with_test_prefix "varobj nscont" {
-    mi_create_dynamic_varobj nscont nstype 1 \
+    mi_create_dynamic_varobj nscont nstype ".*" 1 \
        "create nstype varobj"
 
     mi_list_varobj_children nscont {
@@ -284,7 +284,7 @@ set cmd "python exception_flag = True"
 set re [string_list_to_regexp & {"} $cmd \\ n {"} \r\n ^ done]
 mi_gdb_test $cmd $re
 
-mi_create_dynamic_varobj nstype2 nstype2 1 \
+mi_create_dynamic_varobj nstype2 nstype2 ".*" 1 \
   "create nstype2 varobj"
 
 mi_list_varobj_children nstype2 {
@@ -299,7 +299,8 @@ mi_gdb_test "-var-evaluate-expression me" \
        "evaluate me varobj"
 
 # Regression test for python/14836.
-mi_create_dynamic_varobj children_as_list children_as_list 1 \
+mi_create_dynamic_varobj children_as_list children_as_list \
+    children_as_list_val 1 \
     "printer whose children are returned as a list"
 
 # Test that when a pretty-printer returns a gdb.Value in its to_string, we call
@@ -317,7 +318,7 @@ mi_continue_to_line \
     [gdb_get_line_number {breakpoint bug 14741} ${srcfile}] \
     "step to breakpoint for bug 14741"
 
-mi_create_dynamic_varobj c c 1 \
+mi_create_dynamic_varobj c c "container .* with 1 elements" 1 \
   "create varobj for c"
 
 mi_gdb_test "-var-set-visualizer c ArrayPrinter" \
@@ -330,8 +331,10 @@ mi_list_varobj_children c {
 
 mi_next "next over change of array element"
 
+# 'c' is noticed as changing here due to an artifact of the
+# -var-update implementation.  However, it seems harmless.
 mi_gdb_test "-var-update c" \
-    "\\^done,changelist=\\\[{name=\"c.\\\[0\\\]\",in_scope=\"true\",type_changed=\"false\",has_more=\"0\"}\\\]" \
+    "\\^done,changelist=\\\[{name=\"c\",in_scope=\"true\",type_changed=\"false\",displayhint=\"array\",dynamic=\"1\",has_more=\"0\"},{name=\"c.\\\[0\\\]\",in_scope=\"true\",type_changed=\"false\",has_more=\"0\"}\\\]" \
     "update varobj after element change"
 
 # C++ MI tests

diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index c738b7be505afac665161d61d51f1f87ad81db42..c914ed491501bf77e39a71fe7f34128cb0f5ffb5 100644 (file)
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -1426,11 +1426,11 @@ proc mi_create_varobj_checked { name expression type testname } {
 }
 
 # Same as mi_create_floating_varobj, but assumes the test is creating
-# a dynamic varobj that has children, so the value must be "{...}".
-# The "has_more" attribute is checked.
-proc mi_create_dynamic_varobj {name expression has_more testname} {
+# a dynamic varobj that has children.  The "value" and "has_more"
+# attributes are checked.
+proc mi_create_dynamic_varobj {name expression value has_more testname} {
     mi_gdb_test "-var-create $name @ $expression" \
-       "\\^done,name=\"$name\",numchild=\"0\",value=\"{\\.\\.\\.}\",type=.*,has_more=\"${has_more}\"" \
+       "\\^done,name=\"$name\",numchild=\"0\",value=\"$value\",type=.*,has_more=\"${has_more}\"" \
        $testname
 }
 

diff --git a/gdb/varobj.c b/gdb/varobj.c
index 1d545382f5e68b99aa3aa51ab3b8a606c2e5e129..2c35b911badce00c821a1605ebe25714b8edae29 100644 (file)
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -652,21 +652,6 @@ install_dynamic_child (struct varobj *var,
     }
 }
 
-#if HAVE_PYTHON
-
-static bool
-dynamic_varobj_has_child_method (const struct varobj *var)
-{
-  PyObject *printer = var->dynamic->pretty_printer;
-
-  if (!gdb_python_initialized)
-    return false;
-
-  gdbpy_enter_varobj enter_py (var);
-  return PyObject_HasAttr (printer, gdbpy_children_cst);
-}
-#endif
-
 /* A factory for creating dynamic varobj's iterators.  Returns an
    iterator object suitable for iterating over VAR's children.  */
 
@@ -2178,11 +2163,6 @@ varobj_value_get_print_value (struct value *value,
 
       if (value_formatter)
        {
-         /* First check to see if we have any children at all.  If so,
-            we simply return {...}.  */
-         if (dynamic_varobj_has_child_method (var))
-           return "{...}";
-
          if (PyObject_HasAttr (value_formatter, gdbpy_to_string_cst))
            {
              struct value *replacement;
@@ -2193,7 +2173,7 @@ varobj_value_get_print_value (struct value *value,
                                                                &opts);
 
              /* If we have string like output ...  */
-             if (output != NULL)
+             if (output != nullptr && output != Py_None)
                {
                  /* If this is a lazy string, extract it.  For lazy
                     strings we always print as a string, so set
@@ -2245,6 +2225,13 @@ varobj_value_get_print_value (struct value *value,
              if (replacement)
                value = replacement;
            }
+         else
+           {
+             /* No to_string method, so if there is a 'children'
+                method, return the default.  */
+             if (PyObject_HasAttr (value_formatter, gdbpy_children_cst))
+               return "{...}";
+           }
        }
     }
 #endif