eval/decode: Make sure that U+00C3 is parsed correctly

2 files changed, 8 insertions, 1 deletions

diff --git a/src/nvim/eval/decode.c b/src/nvim/eval/decode.c
index 35e8421716..ce2723147d 100644
--- a/src/nvim/eval/decode.c
+++ b/src/nvim/eval/decode.c
@@ -431,7 +431,10 @@ json_decode_string_cycle_start:
             // and thus cannot possibly be equal to *p. But utf_ptr2char({0xFF,
             // 0}) will return 0xFF, even though 0xFF cannot start any UTF-8
             // code point at all.
-            if (ch >= 0x80 && p_byte == ch) {
+            //
+            // The only exception is U+00C3 which is represented as 0xC3 0x83.
+            if (ch >= 0x80 && p_byte == ch && !(
+                    ch == 0xC3 && p + 1 < e && (uint8_t) p[1] == 0x83)) {
               EMSG2(_("E474: Only UTF-8 strings allowed: %s"), p);
               goto json_decode_string_fail;
             } else if (ch > 0x10FFFF) {
diff --git a/test/functional/eval/json_functions_spec.lua b/test/functional/eval/json_functions_spec.lua
index 59dbb804e4..7ec3882a58 100644
--- a/test/functional/eval/json_functions_spec.lua
+++ b/test/functional/eval/json_functions_spec.lua
@@ -447,6 +447,10 @@ describe('json_decode() function', function()
     eq('\xAB', funcs.json_decode('"\\u00AB"'))
     sp_decode_eq({_TYPE='string', _VAL={'\n\xAB\n'}}, '"\\u0000\\u00AB\\u0000"')
   end)
+
+  it('parses U+00C3 correctly', function()
+    eq('\xC3\x83', funcs.json_decode('"\xC3\x83"'))
+  end)
 end)
 
 describe('json_encode() function', function()