get_name crashes on file named [...parts].svelte

[IlyaSemenov]

If there's a file named [...parts].svelte (syntax used by Sapper), it wouldn't compile because get_name(filename) would crash:

svelte/src/compile/index.ts

Lines 58 to 74 in d548a5a

	function get_name(filename) {
	if (!filename) return null;
	const parts = filename.split(/[\/\\]/);
	if (parts.length > 1 && /^index\.\w+/.test(parts[parts.length - 1])) {
	parts.pop();
	}
	const base = parts.pop()
	.replace(/\..+/, "")
	.replace(/[^a-zA-Z_$0-9]+/g, '_')
	.replace(/^_/, '')
	.replace(/_$/, '')
	.replace(/^(\d)/, '_$1');
	return base[0].toUpperCase() + base.slice(1);
	}

The sequence of .replace(...) leads to the empty string, and then base[0].toUpperCase() crashes with Cannot read property 'toUpperCase' of undefined.

Related Sapper issue: sveltejs/sapper#709

Of course this particular problem can be fixed by prepending the chain of replacements with something like .replace(/\.{2,}/g, "") but perhaps it needs a more generic fix as well? Like if the replacements lead to the empty string, generate the component name with something like Component_${hash(lastPart))}?

[IlyaSemenov]

Also, I think .replace(/\..+/, "") should rather be .replace(/\.[^\.]+$/, "") (remove last file extension, not first). If it were the case, the original problem wouldn't appear in the first place.

file.foo.svelte would become File_Foo which makes perfect sense.

[IlyaSemenov]

I also noticed inconsistency in preparing parts:

• For "usual" svelte files, parts is ['Users', 'semenov', ..., 'some.svelte'] (extension(s) included)
• for index files, parts is ['Users', 'semenov', ..., 'last_dir'] (no extension)

Meaning the suggestion above (removing last file extension) will work inconsistently if de-indexing code is not updated to append the extension, something like:

            if (parts.length > 1) {
                const indexMatch = parts[parts.length - 1].match(/^index(\.\w+)/)
                if (indexMatch) {
                    parts.pop();
                    parts[parts.length - 1] += indexMatch[1]
                }
            }