debuginfo: Add GDB pretty printers for structs and enums.

Author: michaelwoerister

src/compiletest/runtest.rs

@@ -459,7 +459,8 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
         }
 
         _=> {
-            let rust_src_root = find_rust_src_root(config).expect("Could not find Rust source root");
+            let rust_src_root = find_rust_src_root(config)
+                .expect("Could not find Rust source root");
             let rust_pp_module_rel_path = Path::new("./src/etc");
             let rust_pp_module_abs_path = rust_src_root.join(rust_pp_module_rel_path)
                                                        .as_str()

src/etc/gdb_rust_pretty_printing.py

@@ -0,0 +1,225 @@
+# Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution and at
+# http://rust-lang.org/COPYRIGHT.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+import gdb
+
+#===============================================================================
+# GDB Pretty Printing Module for Rust
+#===============================================================================
+
+def register_printers(objfile):
+  "Registers Rust pretty printers for the given objfile"
+  objfile.pretty_printers.append(rust_pretty_printer_lookup_function)
+
+def rust_pretty_printer_lookup_function(val):
+  "Returns the correct Rust pretty printer for the given value if there is one"
+  type_code = val.type.code
+
+  if type_code == gdb.TYPE_CODE_STRUCT:
+    struct_kind = classify_struct(val.type)
+
+    if struct_kind == STRUCT_KIND_STR_SLICE:
+      return RustStringSlicePrinter(val)
+
+    if struct_kind == STRUCT_KIND_TUPLE:
+      return RustTuplePrinter(val)
+
+    if struct_kind == STRUCT_KIND_TUPLE_STRUCT:
+      return RustTupleStructPrinter(val, False)
+
+    if struct_kind == STRUCT_KIND_CSTYLE_VARIANT:
+      return RustCStyleEnumPrinter(val[get_field_at_index(val, 0)])
+
+    if struct_kind == STRUCT_KIND_TUPLE_VARIANT:
+      return RustTupleStructPrinter(val, True)
+
+    if struct_kind == STRUCT_KIND_STRUCT_VARIANT:
+      return RustStructPrinter(val, True)
+
+    return RustStructPrinter(val, False)
+
+  # Enum handling
+  if type_code == gdb.TYPE_CODE_UNION:
+    enum_members = list(val.type.fields())
+    enum_member_count = len(enum_members)
+
+    if enum_member_count == 0:
+      return RustStructPrinter(val, false)
+
+    if enum_member_count == 1:
+      if enum_members[0].name == None:
+        # This is a singleton enum
+        return rust_pretty_printer_lookup_function(val[enum_members[0]])
+      else:
+        assert enum_members[0].name.startswith("RUST$ENCODED$ENUM$")
+        # This is a space-optimized enum
+        last_separator_index = enum_members[0].name.rfind("$")
+        second_last_separator_index = first_variant_name.rfind("$", 0, last_separator_index)
+        disr_field_index = first_variant_name[second_last_separator_index + 1 :
+                                              last_separator_index]
+        disr_field_index = int(disr_field_index)
+
+        sole_variant_val = val[enum_members[0]]
+        disr_field = get_field_at_index(sole_variant_val, disr_field_index)
+        discriminant = int(sole_variant_val[disr_field])
+
+        if discriminant == 0:
+          null_variant_name = first_variant_name[last_separator_index + 1:]
+          return IdentityPrinter(null_variant_name)
+
+        return rust_pretty_printer_lookup_function(sole_variant_val)
+
+    # This is a regular enum, extract the discriminant
+    discriminant_name, discriminant_val = extract_discriminant_value(val)
+    return rust_pretty_printer_lookup_function(val[enum_members[discriminant_val]])
+
+
+
+  return None
+
+#=------------------------------------------------------------------------------
+# Pretty Printer Classes
+#=------------------------------------------------------------------------------
+
+class RustStructPrinter:
+  def __init__(self, val, hide_first_field):
+    self.val = val
+    self.hide_first_field = hide_first_field
+
+  def to_string(self):
+    return self.val.type.tag
+
+  def children(self):
+    cs = []
+    for field in self.val.type.fields():
+      field_name = field.name;
+      if field_name == None:
+        field_name = ""
+      name_value_tuple = ( field_name, self.val[field] )
+      cs.append( name_value_tuple )
+
+    if self.hide_first_field:
+      cs = cs[1:]
+
+    return cs
+
+class RustTuplePrinter:
+  def __init__(self, val):
+    self.val = val
+
+  def to_string(self):
+    return None
+
+  def children(self):
+    cs = []
+    for field in self.val.type.fields():
+      cs.append( ("", self.val[field]) )
+
+    return cs
+
+  def display_hint(self):
+    return "array"
+
+class RustTupleStructPrinter:
+  def __init__(self, val, hide_first_field):
+    self.val = val
+    self.hide_first_field = hide_first_field
+
+  def to_string(self):
+    return self.val.type.tag
+
+  def children(self):
+    cs = []
+    for field in self.val.type.fields():
+      cs.append( ("", self.val[field]) )
+
+    if self.hide_first_field:
+      cs = cs[1:]
+
+    return cs
+
+  def display_hint(self):
+    return "array"
+
+class RustStringSlicePrinter:
+  def __init__(self, val):
+    self.val = val
+
+  def to_string(self):
+    slice_byte_len = self.val["length"]
+    return '"%s"' % self.val["data_ptr"].string(encoding = "utf-8",
+                                                length = slice_byte_len)
+
+class RustCStyleEnumPrinter:
+  def __init__(self, val):
+    assert val.type.code == gdb.TYPE_CODE_ENUM
+    self.val = val
+
+  def to_string(self):
+    return str(self.val)
+
+class IdentityPrinter:
+  def __init__(self, string):
+    self.string
+
+  def to_string(self):
+    return self.string
+
+STRUCT_KIND_REGULAR_STRUCT  = 0
+STRUCT_KIND_TUPLE_STRUCT    = 1
+STRUCT_KIND_TUPLE           = 2
+STRUCT_KIND_TUPLE_VARIANT   = 3
+STRUCT_KIND_STRUCT_VARIANT  = 4
+STRUCT_KIND_CSTYLE_VARIANT  = 5
+STRUCT_KIND_STR_SLICE       = 6
+
+def classify_struct(type):
+  if type.tag == "&str":
+    return STRUCT_KIND_STR_SLICE
+
+  fields = list(type.fields())
+  field_count = len(fields)
+
+  if field_count == 0:
+    return STRUCT_KIND_REGULAR_STRUCT
+
+  if fields[0].artificial:
+    if field_count == 1:
+      return STRUCT_KIND_CSTYLE_VARIANT
+    elif fields[1].name == None:
+      return STRUCT_KIND_TUPLE_VARIANT
+    else:
+      return STRUCT_KIND_STRUCT_VARIANT
+
+  if fields[0].name == None:
+    if type.tag.startswith("("):
+      return STRUCT_KIND_TUPLE
+    else:
+      return STRUCT_KIND_TUPLE_STRUCT
+
+  return STRUCT_KIND_REGULAR_STRUCT
+
+def extract_discriminant_value(enum_val):
+  assert enum_val.type.code == gdb.TYPE_CODE_UNION
+  for variant_descriptor in enum_val.type.fields():
+    variant_val = enum_val[variant_descriptor]
+    for field in variant_val.type.fields():
+      return (field.name, int(variant_val[field]))
+
+def first_field(val):
+  for field in val.type.fields():
+    return field
+
+def get_field_at_index(val, index):
+  i = 0
+  for field in val.type.fields():
+    if i == index:
+      return field
+  return None