feat: add support for removal of packages from a registryfix/support-removed-packages

This adds support for removal of packages from any given registry.
Currently mason.nvim doesn't support this at all and throws an error
when trying to interact with the registry in any way while having a
removed package installed locally.

This ensures that removed packages are available both in the `:Mason` UI
as well as the public Lua APIs. These "synthesized" packages only
supports uninstallation, and metadata such as licenses, categories,
homepage, etc is not available.

1 files changed, 15 insertions, 2 deletions

diff --git a/lua/mason-registry/sources/init.lua b/lua/mason-registry/sources/init.lua
index 765d4904..f468a8ef 100644
--- a/lua/mason-registry/sources/init.lua
+++ b/lua/mason-registry/sources/init.lua
@@ -11,7 +11,7 @@ local log = require "mason-core.log"
 ---@field serialize fun(self: RegistrySource): InstallReceiptRegistry
 ---@field is_same_location fun(self: RegistrySource, other: RegistrySource): boolean
 
----@alias RegistrySourceType '"github"' | '"lua"' | '"file"'
+---@alias RegistrySourceType '"github"' | '"lua"' | '"file"' | '"synthesized"'
 
 ---@class LazySource
 ---@field type RegistrySourceType
@@ -54,6 +54,11 @@ function LazySource.File(id)
     }
 end
 
+function LazySource.Synthesized()
+    local SynthesizedSource = require "mason-registry.sources.synthesized"
+    return SynthesizedSource:new()
+end
+
 ---@param type RegistrySourceType
 ---@param id string
 ---@param init fun(id: string): RegistrySource
@@ -115,6 +120,7 @@ end
 
 ---@class LazySourceCollection
 ---@field list LazySource[]
+---@field synthesized LazySource
 local LazySourceCollection = {}
 LazySourceCollection.__index = LazySourceCollection
 
@@ -123,6 +129,7 @@ function LazySourceCollection:new()
     local instance = {}
     setmetatable(instance, self)
     instance.list = {}
+    instance.synthesized = LazySource:new("synthesized", "synthesized", LazySource.Synthesized)
     return instance
 end
 
@@ -184,7 +191,7 @@ function LazySourceCollection:checksum()
     return vim.fn.sha256(table.concat(registry_ids, ""))
 end
 
----@param opts? { include_uninstalled?: boolean }
+---@param opts? { include_uninstalled?: boolean, include_synthesized?: boolean }
 function LazySourceCollection:iterate(opts)
     opts = opts or {}
 
@@ -197,6 +204,12 @@ function LazySourceCollection:iterate(opts)
                 return source
             end
         end
+
+        -- We've exhausted the true registry sources, fall back to the synthesized registry source.
+        if idx == #self.list + 1 and opts.include_synthesized ~= false then
+            idx = idx + 1
+            return self.synthesized:get()
+        end
     end
 end