fix(lua): remove uri fragment from file paths (#27647)

Problem: Some LSP servers return `textDocument/documentLink` responses
         containing file URIs with line/column numbers in the fragment.
         `vim.uri_to_fname` returns invalid file names for these URIs.

Solution: Remove the URI fragment from file URIs.

2 files changed, 19 insertions, 0 deletions

diff --git a/runtime/lua/vim/uri.lua b/runtime/lua/vim/uri.lua
index 7660dc42e7..b4e4098b91 100644
--- a/runtime/lua/vim/uri.lua
+++ b/runtime/lua/vim/uri.lua
@@ -104,6 +104,10 @@ function M.uri_to_fname(uri)
   if scheme ~= 'file' then
     return uri
   end
+  local fragment_index = uri:find('#')
+  if fragment_index ~= nil then
+    uri = uri:sub(1, fragment_index - 1)
+  end
   uri = M.uri_decode(uri)
   --TODO improve this.
   if is_windows_file_uri(uri) then
diff --git a/test/functional/lua/uri_spec.lua b/test/functional/lua/uri_spec.lua
index e238bc8a82..dacaf95867 100644
--- a/test/functional/lua/uri_spec.lua
+++ b/test/functional/lua/uri_spec.lua
@@ -88,6 +88,12 @@ describe('URI methods', function()
 
         eq('/xy/åäö/ɧ/汉语/↥/🤦/🦄/å/بِيَّ.txt', exec_lua(test_case))
       end)
+
+      it('file path with uri fragment', function()
+        exec_lua("uri = 'file:///Foo/Bar/Baz.txt#fragment'")
+
+        eq('/Foo/Bar/Baz.txt', exec_lua('return vim.uri_to_fname(uri)'))
+      end)
     end)
 
     describe('decode Windows filepath', function()
@@ -184,6 +190,15 @@ describe('URI methods', function()
         ]]
         )
       end)
+
+      it('uri_to_fname returns non-file schema URI with fragment unchanged', function()
+        eq(
+          'scheme://path#fragment',
+          exec_lua [[
+          return vim.uri_to_fname('scheme://path#fragment')
+        ]]
+        )
+      end)
     end)
   end)