Install GSL.natvis (#1112)

Turns out supporting GSL.natvis perfectly is quite difficult.

There is no universal way to consume .natvis files that would satisfy everyone.

I thought the solution was to use the /NATVIS linker option. But it turns out that actually embeds information into the PDB. So I'm not sure how to properly support the Ninja generator...

That's not even accounting for the fact target_link_options doesn't play nicely with /NATVIS

When you just add the file via target_sources the visual studio solution will just pick it up and recognize it without adding it to the PDB file. Which won't affect the binary and is what most devs want.

This all comes down to the fact that /NATVIS files have native integration with visual studio that makes it difficult to use with non-visual studio solutions. /NATVIS almost works but embeds itself into the PDB which not everyone wants, and not everyone generates PDBs either.

Docs for natvis files and /NATVIS
- https://learn.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2022
- https://learn.microsoft.com/en-us/cpp/build/reference/natvis-add-natvis-to-pdb?view=msvc-170

So my current solution is to just simplify the existing CMake code, and install the natvis so the user can decide.

closes #1084

CMakeLists.txt

@@ -1,6 +1,4 @@
 cmake_minimum_required(VERSION 3.14...3.16)
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/")
-include(gsl_functions)
 
 project(GSL VERSION 4.0.0 LANGUAGES CXX)
 
@@ -19,8 +17,7 @@ target_compile_features(GSL INTERFACE "cxx_std_14")
 # Setup include directory
 add_subdirectory(include)
 
-# Add natvis file
-gsl_add_native_visualizer_support()
+target_sources(GSL INTERFACE $<BUILD_INTERFACE:${GSL_SOURCE_DIR}/GSL.natvis>)
 
 if (GSL_TEST)
     enable_testing()
@@ -46,4 +43,6 @@ if (GSL_INSTALL)
     write_basic_package_version_file(${gls_config_version} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
 
     install(FILES ${gls_config_version} DESTINATION ${cmake_files_install_dir})
+
+    install(FILES GSL.natvis DESTINATION ${cmake_files_install_dir})
 endif()

README.md

@@ -214,7 +214,5 @@ target_link_libraries(foobar PRIVATE Microsoft.GSL::GSL)
 ```
 
 ## Debugging visualization support
-For Visual Studio users, the file [GSL.natvis](./GSL.natvis) in the root directory of the repository can be added to your project if you would like more helpful visualization of GSL types in the Visual Studio debugger than would be offered by default.
 
-If you are using CMake this will be done automatically for you.
-See `GSL_VS_ADD_NATIVE_VISUALIZERS`
+For Visual Studio users, the file [GSL.natvis](./GSL.natvis) in the root directory of the repository can be added to your project if you would like more helpful visualization of GSL types in the Visual Studio debugger than would be offered by default.