Only emit ternary :-spacing diagnostics when a : is present

src/julia/parser.jl

@@ -686,19 +686,20 @@ function parse_cond(ps::ParseState)
     end
     parse_eq_star(ParseState(ps, range_colon_enabled=false))
     t = peek_token(ps)
-    if !preceding_whitespace(t)
+    had_colon = kind(t) == K":"
+    if had_colon && !preceding_whitespace(t)
         # a ? b: c  ==>  (? a b (error-t) c)
         bump_invisible(ps, K"error", TRIVIA_FLAG,
                        error="space required before `:` in `?` expression")
     end
-    if kind(t) == K":"
+    if had_colon
         bump(ps, TRIVIA_FLAG)
     else
         # a ? b c  ==>  (? a b (error-t) c)
         bump_invisible(ps, K"error", TRIVIA_FLAG, error="`:` expected in `?` expression")
     end
     t = peek_token(ps; skip_newlines = true)
-    if !preceding_whitespace(t)
+    if had_colon && !preceding_whitespace(t)
         # a ? b :c  ==>  (? a b (error-t) c)
         bump_invisible(ps, K"error", TRIVIA_FLAG,
                        error="space required after `:` in `?` expression")

test/parser.jl

@@ -92,6 +92,7 @@ tests = [
         "a ? b: c"    => "(? a b (error-t) c)"
         "a ? b :c"    => "(? a b (error-t) c)"
         "a ? b c"     => "(? a b (error-t) c)"
+        "a ? b)"      => "(? a b (error-t) (error))"
         "A[x ? y : end]" => "(ref A (? x y end))"
     ],
     JuliaSyntax.parse_arrow => [