Add documentation about Microsoft provided debuggers and CodeView/PDB… (#1406)

Co-authored-by: Yuki Okushi <jtitor@2k36.org>
Co-authored-by: Ridwan Abdilahi <riabdila@microsoft.com>

src/debugging-support-in-rustc.md

@@ -3,7 +3,7 @@
 <!-- toc -->
 
 This document explains the state of debugging tools support in the Rust compiler (rustc).
-It gives an overview of GDB, LLDB,
+It gives an overview of GDB, LLDB, WinDbg/CDB,
 as well as infrastructure around Rust compiler to debug Rust code.
 If you want to learn how to debug the Rust compiler itself,
 see [Debugging the Compiler].
@@ -42,6 +42,15 @@ Debugging Information Entry (DIE) which stores the information as "tags" to deno
 variables etc., e.g., `DW_TAG_variable`, `DW_TAG_pointer_type`, `DW_TAG_subprogram` etc.
 You can also invent your own tags and attributes.
 
+### CodeView/PDB
+
+[PDB] (Program Database) is a file format created by Microsoft that contains debug information.
+PDBs can be consumed by debuggers such as WinDbg/CDB and other tools to display debug information.
+A PDB contains multiple streams that describe debug information about a specific binary such
+as types, symbols, and source files used to compile the given binary. CodeView is another
+format which defines the structure of [symbol records] and [type records] that appear within
+PDB streams.
+
 ## Supported debuggers
 
 ### GDB
@@ -104,6 +113,27 @@ LLDB has Rust-like value and type output.
 * LLDB has a plugin architecture but that does not work for language support.
 * GDB generally works better on Linux.
 
+### WinDbg/CDB
+
+Microsoft provides [Windows Debugging Tools] such as the Windows Debugger (WinDbg) and
+the Console Debugger (CDB) which both support debugging programs written in Rust. These
+debuggers parse the debug info for a binary from the `PDB`, if available, to construct a
+visualization to serve up in the debugger.
+
+#### Natvis
+
+Both WinDbg and CDB support defining and viewing custom visualizations for any given type
+within the debugger using the Natvis framework. The Rust compiler defines a set of Natvis
+files that define custom visualizations for a subset of types in the standard libraries such
+as, `std, core and alloc`. These Natvis files are embedded into `PDBs` generated by the
+`*-pc-windows-msvc` target triples to automatically enable these custom visualizations when
+debugging. This default can be overridden by setting the `strip` rustc flag to either `debuginfo`
+or `symbols`.
+
+Rust has support for embedding Natvis files for crates outside of the standard libraries by
+using the `#[debugger_visualizer]` attribute. For more details on how to embed debugger visualizers
+please refer to the `#[debugger_visualizer]` attribute in [the unstable book](https://doc.rust-lang.org/unstable-book/language-features/debugger-visualizer.html).
+
 ## DWARF and `rustc`
 
 [DWARF] is the standard way compilers generate debugging information that debuggers read.
@@ -316,3 +346,7 @@ but may have to add some mode to let the compiler understand some extensions.
 [Apple developer documentation for System Integrity Protection]: https://developer.apple.com/library/archive/releasenotes/MacOSX/WhatsNewInOSX/Articles/MacOSX10_11.html#//apple_ref/doc/uid/TP40016227-SW11
 [https://github.com/rust-lang/lldb]: https://github.com/rust-lang/lldb
 [https://github.com/rust-lang/llvm-project]: https://github.com/rust-lang/llvm-project
+[PDB]: https://llvm.org/docs/PDB/index.html
+[symbol records]: https://llvm.org/docs/PDB/CodeViewSymbols.html
+[type records]: https://llvm.org/docs/PDB/CodeViewTypes.html
+[Windows Debugging Tools]: https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/