From cad42e0d330d8d3476f2217fe4f14f2f5e34e691 Mon Sep 17 00:00:00 2001
From: Wesley Wiser <wesleywiser@microsoft.com>
Date: Tue, 29 Jun 2021 15:32:03 -0400
Subject: [PATCH] Add natvis for cell types

---
 src/etc/natvis/libcore.natvis      | 34 +++++++++++++
 src/test/debuginfo/mutable-locs.rs | 77 +++++++++++++++++++++++++-----
 src/test/debuginfo/rwlock-read.rs  |  6 +--
 3 files changed, 102 insertions(+), 15 deletions(-)

diff --git a/src/etc/natvis/libcore.natvis b/src/etc/natvis/libcore.natvis
index b5899cf9319..96459adb6b8 100644
--- a/src/etc/natvis/libcore.natvis
+++ b/src/etc/natvis/libcore.natvis
@@ -1,5 +1,39 @@
 <?xml version="1.0" encoding="utf-8"?>
 <AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+  <Type Name="core::cell::Cell&lt;*&gt;">
+    <DisplayString>{value.value}</DisplayString>
+    <Expand>
+      <ExpandedItem>value.value</ExpandedItem>
+    </Expand>
+  </Type>
+  <Type Name="core::cell::Ref&lt;*&gt;">
+    <DisplayString>{value}</DisplayString>
+    <Expand>
+      <ExpandedItem>value</ExpandedItem>
+    </Expand>
+  </Type>
+  <Type Name="core::cell::RefMut&lt;*&gt;">
+    <DisplayString>{value}</DisplayString>
+    <Expand>
+      <ExpandedItem>value</ExpandedItem>
+    </Expand>
+  </Type>
+  <Type Name="core::cell::RefCell&lt;*&gt;">
+    <DisplayString>{value.value}</DisplayString>
+    <Expand>
+      <Item Name="[Borrow state]" Condition="borrow.value.value == 0">"Unborrowed",sb</Item>
+      <Item Name="[Borrow state]" Condition="borrow.value.value &gt; 0">"Immutably borrowed",sb</Item>
+      <Item Name="[Borrow state]" Condition="borrow.value.value &lt; 0">"Mutably borrowed",sb</Item>
+      <ExpandedItem>value.value</ExpandedItem>
+    </Expand>
+  </Type>
+  <Type Name="core::cell::UnsafeCell&lt;*&gt;">
+    <DisplayString>{value}</DisplayString>
+    <Expand>
+      <ExpandedItem>value</ExpandedItem>
+    </Expand>
+  </Type>
+
   <Type Name="core::num::nonzero::NonZeroI8">
     <DisplayString>{__0}</DisplayString>
   </Type>
diff --git a/src/test/debuginfo/mutable-locs.rs b/src/test/debuginfo/mutable-locs.rs
index 428a7e8d9c0..688483e43e4 100644
--- a/src/test/debuginfo/mutable-locs.rs
+++ b/src/test/debuginfo/mutable-locs.rs
@@ -9,26 +9,64 @@
 // cdb-command: g
 
 // cdb-command:dx static_c,d
-// cdb-check:static_c,d       [Type: core::cell::Cell<i32>]
-// cdb-check:    [...] value            [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:static_c,d       : 10 [Type: core::cell::Cell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::Cell<i32>]
 
 // cdb-command: dx static_c.value,d
-// cdb-check:static_c.value,d [Type: core::cell::UnsafeCell<i32>]
-// cdb-check:    [...] value            : 10 [Type: int]
+// cdb-check:static_c.value,d : 10 [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::UnsafeCell<i32>]
 
 // cdb-command:  dx dynamic_c,d
-// cdb-check:dynamic_c,d      [Type: core::cell::RefCell<i32>]
-// cdb-check:    [...] borrow           [Type: core::cell::Cell<isize>]
-// cdb-check:    [...] value            [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:dynamic_c,d      : 15 [Type: core::cell::RefCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefCell<i32>]
+// cdb-check:    [Borrow state]   : Unborrowed
 
 // cdb-command: dx dynamic_c.value,d
-// cdb-check:dynamic_c.value,d [Type: core::cell::UnsafeCell<i32>]
-// cdb-check:    [...] value            : 15 [Type: int]
+// cdb-check:dynamic_c.value,d : 15 [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::UnsafeCell<i32>]
 
 // cdb-command: dx b,d
-// cdb-check:b,d              [Type: core::cell::RefMut<i32>]
-// cdb-check:    [...] value            : [...] : 42 [Type: int *]
-// cdb-check:    [...] borrow           [Type: core::cell::BorrowRefMut]
+// cdb-check:b,d              : 42 [Type: core::cell::RefMut<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefMut<i32>]
+// cdb-check:    42 [Type: int]
+
+// cdb-command: g
+
+// cdb-command: dx dynamic_c,d
+// cdb-check:dynamic_c,d      : 15 [Type: core::cell::RefCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefCell<i32>]
+// cdb-check:    [Borrow state]   : Immutably borrowed
+
+// cdb-command: dx r_borrow,d
+// cdb-check:r_borrow,d       : 15 [Type: core::cell::Ref<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::Ref<i32>]
+// cdb-check:    15 [Type: int]
+
+// cdb-command: g
+
+// cdb-command: dx dynamic_c,d
+// cdb-check:dynamic_c,d      : 15 [Type: core::cell::RefCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefCell<i32>]
+// cdb-check:    [Borrow state]   : Unborrowed
+
+// cdb-command: g
+
+// cdb-command: dx dynamic_c,d
+// cdb-check:dynamic_c,d      : 15 [Type: core::cell::RefCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefCell<i32>]
+// cdb-check:    [Borrow state]   : Mutably borrowed
+
+// cdb-command: dx r_borrow_mut,d
+// cdb-check:r_borrow_mut,d   : 15 [Type: core::cell::RefMut<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefMut<i32>]
+// cdb-check:    15 [Type: int]
+
+// cdb-command: g
+
+// cdb-command: dx dynamic_c,d
+// cdb-check:dynamic_c,d      : 15 [Type: core::cell::RefCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::RefCell<i32>]
+// cdb-check:    [Borrow state]   : Unborrowed
 
 #![allow(unused_variables)]
 
@@ -46,6 +84,21 @@ fn main() {
     *b = 42;
 
     zzz(); // #break
+
+    // Check that `RefCell`'s borrow state visualizes correctly
+    {
+        let r_borrow = dynamic_c.borrow();
+        zzz(); // #break
+    }
+
+    zzz(); // #break
+
+    {
+        let r_borrow_mut = dynamic_c.borrow_mut();
+        zzz(); // #break
+    }
+
+    zzz(); // #break
 }
 
 fn zzz() {()}
diff --git a/src/test/debuginfo/rwlock-read.rs b/src/test/debuginfo/rwlock-read.rs
index ac652c8ccf4..e1c10a4d37f 100644
--- a/src/test/debuginfo/rwlock-read.rs
+++ b/src/test/debuginfo/rwlock-read.rs
@@ -11,15 +11,15 @@
 // cdb-command:dx l
 // cdb-check:l                [Type: std::sync::rwlock::RwLock<i32>]
 // cdb-check:    [...] poison           [Type: std::sync::poison::Flag]
-// cdb-check:    [...] data             [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:    [...] data             : 0 [Type: core::cell::UnsafeCell<i32>]
 //
 // cdb-command:dx r
 // cdb-check:r                [Type: std::sync::rwlock::RwLockReadGuard<i32>]
 // cdb-check:    [...] lock             : [...] [Type: std::sync::rwlock::RwLock<i32> *]
 //
 // cdb-command:dx r.lock->data,d
-// cdb-check:r.lock->data,d   [Type: core::cell::UnsafeCell<i32>]
-// cdb-check:    [...] value            : 0 [Type: int]
+// cdb-check:r.lock->data,d   : 0 [Type: core::cell::UnsafeCell<i32>]
+// cdb-check:    [<Raw View>]     [Type: core::cell::UnsafeCell<i32>]
 
 #[allow(unused_variables)]