invalid/key-no-whitespace.toml is actually valid.

[pygy]

According to the spec:

Under that, and until the next key or EOF are the key/values of that key group. Keys are on the left of the equals sign and values are on the right. Keys start with the first non-whitespace character and end with the last non-whitespace character before the equals sign. Key/value pairs within key groups are unordered.

This also means that valid/key-special-chars.toml is invalid.

[BurntSushi]

I think I'm going to need an interpretation or something from you, because to me

Keys start with the first non-whitespace character and end with the last non-whitespace character before the equals sign.

implies the pattern ([^ \t]+)[ \t]+=, where the key is captured in the parentheses.

If an = sign weren't allowed in the key, then I think the language would have read:

Keys start with the first non-whitespace character and end either with the last character before the = or the last non-whitespace character.

This is why specifications need formal grammars. It is too difficult to capture all of the subtleties in English.

[BurntSushi]

I've re-read the sentence. I think I've more or less convinced myself to come to your side of things. Bah. I'll update the tests.