feat(treesitter)!: don't parse tree in get_parser() or start()

**Problem:** `vim.treesitter.get_parser()` and `vim.treesitter.start()`
both parse the tree before returning it. This is problematic because if
this is a sync parse, it will stall the editor on large files. If it is
an async parse, the functions return stale trees.

**Solution:** Remove this parsing side effect and leave it to the user
to parse the returned trees, either synchronously or asynchronously.

1 files changed, 4 insertions, 0 deletions

diff --git a/test/functional/treesitter/language_spec.lua b/test/functional/treesitter/language_spec.lua
index 120a15d7f9..a93b1063a1 100644
--- a/test/functional/treesitter/language_spec.lua
+++ b/test/functional/treesitter/language_spec.lua
@@ -117,6 +117,7 @@ describe('treesitter language API', function()
       '<node translation_unit>',
       exec_lua(function()
         local langtree = vim.treesitter.get_parser(0, 'c')
+        langtree:parse()
         local tree = langtree:tree_for_range({ 1, 3, 1, 3 })
         return tostring(tree:root())
       end)
@@ -133,6 +134,7 @@ describe('treesitter language API', function()
       '<node translation_unit>',
       exec_lua(function()
         local langtree = vim.treesitter.get_parser(0, 'c')
+        langtree:parse()
         local tree = langtree:tree_for_range({ 10, 10, 10, 10 })
         return tostring(tree:root())
       end)
@@ -149,6 +151,7 @@ describe('treesitter language API', function()
       '<node primitive_type>',
       exec_lua(function()
         local langtree = vim.treesitter.get_parser(0, 'c')
+        langtree:parse()
         local node = langtree:named_node_for_range({ 1, 3, 1, 3 })
         return tostring(node)
       end)
@@ -160,6 +163,7 @@ describe('treesitter language API', function()
 
     exec_lua(function()
       _G.langtree = vim.treesitter.get_parser(0, 'lua')
+      _G.langtree:parse()
       _G.node = _G.langtree:node_for_range({ 0, 3, 0, 3 })
     end)