@StScAllen := is not broken, your example contained a redundant space between the colon : and equal sign =. Here is a link to a working example.

PS: You can wrap multiple lines of code in triple backticks so it is rendered in a monospaced font.

Can be closed because of a non issue.

Why was this closed? The OP is reporting the fact that the error message that you get when you mis-type ":=" as ": =" is misleading. That's a valid complaint.

Also, I remember reading a similar issue in the past (about misleading errors related to for statements parsing).

Ah, it was #17328. The typo is different, but the misleading message was the same: a not-very-informative "missing { after for clause".

On tip, the error message is:

syntax error: unexpected :, expecting { after for clause

a little better (at least it mentions :).

Leaving for someone else to decide if improving the reported error for a broken : = is worth it.

@ALTree You're right I overlooked this sentence:

For loop generates error that opening { brace is missing. Rather than
informing user the := operator is severed.

I'll take a look - it's not hard to recognize this case, but it's unclear it's worth it. The better thing might be to print column/offset information in error messages (we do have that information now), as it would point much more clearly at the place where the error occurred (rather than just mentioning a line).

What's a column?

I think with column he means the index/position in the line.

For more arguing about columns: #10324 (comment). :^)

At tip, the error reported is:

tmp.go:7: syntax error: unexpected :, expecting { after for clause

which is pretty clear. That is, this has been fixed as part of another issue.
Furthermore, once the compiler reports column information (#10324), the reported error is:

tmp.go:7:8: syntax error: unexpected :, expecting { after for clause

pin-pointing the offending token exactly. Once 1.9 is out, the playground will behave the same.

Closing as there's nothing else to do here.