fix(loaders): keep recording sources across a nested lua-load

lua/luasnip/loaders/from_lua.lua

@@ -43,7 +43,7 @@ local M = {}
 -- It is not exported, because it will (in its current state) only ever be used
 -- in one place, and it feels a bit wrong to expose put a function into `M`.
 -- Instead, it is inserted into the global environment before a luasnippet-file
--- is loaded, and removed from it immediately when this is done
+-- is loaded, and the previous value restored immediately when this is done
 local function get_loaded_file_debuginfo()
 	-- we can skip looking at the first four stackframes, since
 	-- 1   is this function
@@ -155,14 +155,20 @@ local function _luasnip_load_file(file)
 	-- Since this function has to reach the snippet-constructor, and fenvs
 	-- aren't inherited by called functions, we have to set it in the global
 	-- environment.
+	-- Save and restore, don't unconditionally nil: this function is re-entrant.
+	-- A snippet-file may, while it is executing, cause another file to be
+	-- loaded (for example by requiring a module from a plugin that registers a
+	-- collection in its setup), and clearing the global on return from that
+	-- inner load would silence source-recording for the rest of the outer file.
+	local prev_get_debuginfo = _G.__luasnip_get_loaded_file_frame_debuginfo
 	_G.__luasnip_get_loaded_file_frame_debuginfo = util.ternary(
 		session.config.loaders_store_source,
 		get_loaded_file_debuginfo,
 		nil
 	)
 	local run_ok, file_snippets_or_err, file_autosnippets = pcall(func)
-	-- immediately nil it.
-	_G.__luasnip_get_loaded_file_frame_debuginfo = nil
+	-- immediately restore it.
+	_G.__luasnip_get_loaded_file_frame_debuginfo = prev_get_debuginfo
 
 	if not run_ok then
 		local err = file_snippets_or_err

tests/data/lua-snippets/nested-load/inner/all.lua

@@ -0,0 +1 @@
+return { s("nested_inner", t("inner")) }

tests/data/lua-snippets/nested-load/outer/all.lua

@@ -0,0 +1,13 @@
+-- Loading this file triggers another load while it is still executing, as
+-- happens when a snippet-file requires a module from a plugin that registers
+-- its own collection.
+local before = s("nested_before", t("before"))
+
+require("luasnip.loaders.from_lua").load({
+	paths = os.getenv("LUASNIP_SOURCE")
+		.. "/tests/data/lua-snippets/nested-load/inner",
+})
+
+local after = s("nested_after", t("after"))
+
+return { before, after }

tests/integration/source_spec.lua

@@ -2,6 +2,7 @@ local ls_helpers = require("helpers")
 local exec_lua, feed, exec =
 	ls_helpers.exec_lua, ls_helpers.feed, ls_helpers.exec
 local Screen = require("test.functional.ui.screen")
+local assert = ls_helpers.assert
 
 describe("loaders:", function()
 	local screen
@@ -59,6 +60,37 @@ describe("loaders:", function()
 		})
 	end)
 
+	it("lua: stores source after a nested load.", function()
+		setup({
+			no_snip_globals = true,
+			setup_extend = { loaders_store_source = true },
+		})
+		exec_lua(
+			string.format(
+				[[require("luasnip.loaders.from_lua").load({paths="%s"})]],
+				os.getenv("LUASNIP_SOURCE")
+					.. "/tests/data/lua-snippets/nested-load/outer"
+			)
+		)
+
+		-- `nested_after` is defined after the outer file triggers a load of
+		-- the inner collection, and used to end up without a source.
+		assert.eq(
+			{
+				nested_before = true,
+				nested_inner = true,
+				nested_after = true,
+			},
+			exec_lua([[
+				local has_source = {}
+				for _, snip in ipairs(ls.get_snippets("all")) do
+					has_source[snip.trigger] = ls.snippet_source.get(snip) ~= nil
+				end
+				return has_source
+			]])
+		)
+	end)
+
 	it("vscode: error-message when parser not installed.", function()
 		setup({
 			no_snip_globals = true,