Rollup merge of rust-lang#53112 - fukatani:pretty-print-btreeset, r=michaelwoerister

pretty print BTreeSet

I want pretty printing for BTreeSet.
```rust
use std::collections::*;

fn main() {
  let mut s = BTreeSet::new();
  s.insert(5);
  s.insert(3);
  s.insert(7);
  s.remove(&3);
  println!("{:?}", s);
}
```

```
(gdb) b 9
(gdb) p s
$1 = BTreeSet<i32> with 2 elements = {[0] = 5, [1] = 7}
```
This is analogy of pretty printing for C++ std::set.

Author: kennytm

src/etc/debugger_pretty_printers_common.py

@@ -48,6 +48,7 @@
 TYPE_KIND_REGULAR_UNION     = 17
 TYPE_KIND_OS_STRING         = 18
 TYPE_KIND_STD_VECDEQUE      = 19
+TYPE_KIND_STD_BTREESET      = 20
 
 ENCODED_ENUM_PREFIX = "RUST$ENCODED$ENUM$"
 ENUM_DISR_FIELD_NAME = "RUST$ENUM$DISR"
@@ -71,6 +72,9 @@
                             STD_VECDEQUE_FIELD_NAME_HEAD,
                             STD_VECDEQUE_FIELD_NAME_BUF]
 
+# std::collections::BTreeSet<> related constants
+STD_BTREESET_FIELD_NAMES = ["map"]
+
 # std::String related constants
 STD_STRING_FIELD_NAMES = ["vec"]
 
@@ -175,6 +179,11 @@ def __classify_struct(self):
             self.__conforms_to_field_layout(STD_VECDEQUE_FIELD_NAMES)):
             return TYPE_KIND_STD_VECDEQUE
 
+        # STD COLLECTION BTREESET
+        if (unqualified_type_name.startswith("BTreeSet<") and
+                self.__conforms_to_field_layout(STD_BTREESET_FIELD_NAMES)):
+            return TYPE_KIND_STD_BTREESET
+
         # STD STRING
         if (unqualified_type_name.startswith("String") and
             self.__conforms_to_field_layout(STD_STRING_FIELD_NAMES)):
@@ -358,6 +367,19 @@ def extract_tail_head_ptr_and_cap_from_std_vecdeque(vec_val):
     return (tail, head, data_ptr, capacity)
 
 
+def extract_length_and_ptr_from_std_btreeset(vec_val):
+    assert vec_val.type.get_type_kind() == TYPE_KIND_STD_BTREESET
+    map = vec_val.get_child_at_index(0)
+    root = map.get_child_at_index(0)
+    length = map.get_child_at_index(1).as_integer()
+    node = root.get_child_at_index(0)
+    ptr = node.get_child_at_index(0)
+    unique_ptr_val = ptr.get_child_at_index(0)
+    data_ptr = unique_ptr_val.get_child_at_index(0)
+    assert data_ptr.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_PTR
+    return (length, data_ptr)
+
+
 def extract_length_and_ptr_from_slice(slice_val):
     assert (slice_val.type.get_type_kind() == TYPE_KIND_SLICE or
             slice_val.type.get_type_kind() == TYPE_KIND_STR_SLICE)

src/etc/gdb_rust_pretty_printing.py

@@ -127,6 +127,9 @@ def rust_pretty_printer_lookup_function(gdb_val):
     if type_kind == rustpp.TYPE_KIND_STD_VECDEQUE:
         return RustStdVecDequePrinter(val)
 
+    if type_kind == rustpp.TYPE_KIND_STD_BTREESET:
+        return RustStdBTreeSetPrinter(val)
+
     if type_kind == rustpp.TYPE_KIND_STD_STRING:
         return RustStdStringPrinter(val)
 
@@ -299,6 +302,29 @@ def children(self):
             yield (str(index), (gdb_ptr + index).dereference())
 
 
+class RustStdBTreeSetPrinter(object):
+    def __init__(self, val):
+        self.__val = val
+
+    @staticmethod
+    def display_hint():
+        return "array"
+
+    def to_string(self):
+        (length, data_ptr) = \
+            rustpp.extract_length_and_ptr_from_std_btreeset(self.__val)
+        return (self.__val.type.get_unqualified_type_name() +
+                ("(len: %i)" % length))
+
+    def children(self):
+        (length, data_ptr) = \
+            rustpp.extract_length_and_ptr_from_std_btreeset(self.__val)
+        val = GdbValue(data_ptr.get_wrapped_value().dereference()).get_child_at_index(3)
+        gdb_ptr = val.get_wrapped_value()
+        for index in xrange(length):
+            yield (str(index), gdb_ptr[index])
+
+
 class RustStdStringPrinter(object):
     def __init__(self, val):
         self.__val = val

src/test/debuginfo/pretty-std-collections.rs

@@ -0,0 +1,50 @@
+// Copyright 2018 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.
+
+// ignore-windows failing on win32 bot
+// ignore-freebsd: gdb package too new
+// ignore-android: FIXME(#10381)
+// compile-flags:-g
+// min-gdb-version 7.7
+// min-lldb-version: 310
+
+// === GDB TESTS ===================================================================================
+
+// gdb-command: run
+
+// gdb-command: print btree_set
+// gdb-check:$1 = BTreeSet<i32>(len: 3) = {3, 5, 7}
+
+// gdb-command: print vec_deque
+// gdb-check:$2 = VecDeque<i32>(len: 3, cap: 8) = {5, 3, 7}
+
+#![allow(unused_variables)]
+use std::collections::BTreeSet;
+use std::collections::VecDeque;
+
+
+fn main() {
+
+    // BTreeSet
+    let mut btree_set = BTreeSet::new();
+    btree_set.insert(5);
+    btree_set.insert(3);
+    btree_set.insert(7);
+
+    // VecDeque
+    let mut vec_deque = VecDeque::new();
+    vec_deque.push_back(5);
+    vec_deque.push_back(3);
+    vec_deque.push_back(7);
+
+    zzz(); // #break
+}
+
+fn zzz() { () }