[Visualizers] Fix SmallVector<T> visualizer for T inside an anonymous namespace. Use `value_type` instead of `$T1`.

[curdeius]

Summary

At least on MSVC 2022, using $T1 does not work.

[RKSimon]

llvm/utils/LLVMVisualizers/llvm.natvis

203

We have other users of $T1* - such as for llvm::Optional<>- do they still work?

[RKSimon]

I've just tried this and current trunk seems to work fine with VS2022 - please do you have a specific repro?

[curdeius]

I hit this problem when working on clang-format.
In particular AnnotatingParser has SmallVector<Context, 8> Contexts; that did not work.
I'm using MSVC 2022 (14.31.31103, 17.1.0 preview 3.0, but that problem is there for a few weeks at least).

Using $T1 I get:

Using value_type, I get:

and

Maybe I should file a bug to MSVC?

BTW, the visualizer for llvm::Optional doesn't look good either.
It should be something like this:

<Type Name="llvm::Optional&lt;*&gt;">
  <DisplayString Condition="!Storage.hasVal">None</DisplayString>
  <DisplayString Condition="Storage.hasVal">{Storage.value}</DisplayString>
  <Expand>
    <Item Name="[underlying]" Condition="Storage.hasVal">Storage.value</Item>
  </Expand>
</Type>

so use Storage.value instead of *(($T1 *)(unsigned char *)Storage.storage.buffer).
It was changed back in February 2019 in commit https://github.com/llvm/llvm-project/commit/fb9730575086b3c2ba38a1aabf3106b01339888b.
Should I create a patch for Opional visualizer?

[curdeius]

Strangely enough, using $T1 and $T1 * in other contexts than AnnotatingParser::Contexts works ok.

[RKSimon]

Ah - that might be it - I was checking it with SmallVector<int> - non-POD might still break it.

A llvm::Optional<> fix would be appreciated - cheers.

Do you see any warning spam when you enable Natvis diagnostics in VisualStudio?
https://docs.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects

[curdeius]

Oh, natvis diagnostics enabled shows an error:

Natvis: E:\src\llvm-project\llvm\utils\LLVMVisualizers\llvm.natvis(30,23): Error: identifier "clang::format::`anonymous namespace'" is undefined
    Error while evaluating '(clang::format::`anonymous namespace'::AnnotatingParser::Context*)BeginX' in the context of type 'FormatTests.exe!llvm::SmallVectorImpl<clang::format::`anonymous namespace'::AnnotatingParser::Context>'.

so the anonymous namespace is making things fail.
To my understanding, it's probably because $T1 works like a macro, so a textual replacement...

[RKSimon]

LGTM - cheers

llvm/utils/LLVMVisualizers/llvm.natvis

 <?xml version="1.0" encoding="utf-8"?>
 <!--
 Visual Studio Native Debugging Visualizers for LLVM
 
 For Visual Studio 2013 only, put this file into 
 "%USERPROFILE%\Documents\Visual Studio 2013\Visualizers" or create a symbolic link so it updates automatically.
 
 For later versions of Visual Studio, no setup is required.
 -->
 <AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
   <Type Name="llvm::SmallVectorImpl&lt;*&gt;">
     <DisplayString IncludeView ="elt0" Condition="Size == 0"></DisplayString>
-    <DisplayString IncludeView ="elt0">{(($T1*)BeginX)[0]}{*this,view(elt1)}</DisplayString>
+    <DisplayString IncludeView ="elt0">{((value_type*)BeginX)[0]}{*this,view(elt1)}</DisplayString>
     <DisplayString IncludeView ="elt1" Condition="Size == 1"></DisplayString>
-    <DisplayString IncludeView ="elt1">, {(($T1*)BeginX)[1]}{*this,view(elt2)}</DisplayString>
+    <DisplayString IncludeView ="elt1">, {((value_type*)BeginX)[1]}{*this,view(elt2)}</DisplayString>
     <DisplayString IncludeView ="elt2" Condition="Size == 2"></DisplayString>
-    <DisplayString IncludeView ="elt2">, {(($T1*)BeginX)[2]}{*this,view(elt3)}</DisplayString>
+    <DisplayString IncludeView ="elt2">, {((value_type*)BeginX)[2]}{*this,view(elt3)}</DisplayString>
     <DisplayString IncludeView ="elt3" Condition="Size == 3"></DisplayString>
-    <DisplayString IncludeView ="elt3">, {(($T1*)BeginX)[3]}{*this,view(elt4)}</DisplayString>
+    <DisplayString IncludeView ="elt3">, {((value_type*)BeginX)[3]}{*this,view(elt4)}</DisplayString>
     <DisplayString IncludeView ="elt4" Condition="Size == 4"></DisplayString>
     <DisplayString IncludeView ="elt4">, /* {Size - 4} more*/ </DisplayString>
     <DisplayString Condition="Size == 0">empty</DisplayString>
     <DisplayString Condition="Size != 0">{{{*this,view(elt0)}}}</DisplayString>
     <DisplayString>Uninitialized</DisplayString>
     <Expand>
       <Item Name="[size]">Size</Item>
       <Item Name="[capacity]">Capacity</Item>
       <ArrayItems>
         <Size>Size</Size>
-        <ValuePointer>($T1*)BeginX</ValuePointer>
+        <ValuePointer>(value_type*)BeginX</ValuePointer>
       </ArrayItems>
     </Expand>
   </Type>
   <Type Name="llvm::APInt">
     <!-- For now, only handle up to 64-bit unsigned ints -->
     <DisplayString Condition="BitWidth &lt;= 64">{U.VAL}</DisplayString>
     <DisplayString>Cannot visualize APInts longer than 64 bits</DisplayString>
   </Type>
<Type Name="llvm::Triple">
     <DisplayString>{Data}</DisplayString>
   </Type>
   
   <Type Name="llvm::Optional&lt;*&gt;">
     <DisplayString Condition="!Storage.hasVal">None</DisplayString>
     <DisplayString Condition="Storage.hasVal">{Storage.value}</DisplayString>
     <Expand>
       <Item Name="[underlying]" Condition="Storage.hasVal">Storage.value</Item>
     </Expand>
   </Type>
 
   <Type Name="llvm::Expected&lt;*&gt;">
     <DisplayString Condition="HasError">Error</DisplayString>
     <DisplayString Condition="!HasError">{*((storage_type *)TStorage.buffer)}</DisplayString>
     <Expand>
       <Item Name="[value]" Condition="!HasError">*((storage_type *)TStorage.buffer)</Item>
       <Item Name="[error]" Condition="HasError">*((error_type *)ErrorStorage.buffer)</Item>