[PATCH] D71115: [TableGen] Add a permissive version of !con.

[Simon Tatham via Phabricator via llvm-commits]

simon_tatham added a comment.

Another even sillier thought I considered was to change `!con` itself so that it can accept an unset `?` value as a dag operator, and only insists that the operands that have //defined// operators should all agree with each other. That would have been even terser!

But you can't write a dag with an unset operator node easily: `(? 1, 2, 3)` isn't valid input syntax for a dag, even though there are things you can do that will cause `-print-records` to produce it as output. Also, it's surely setting a bad precedent...


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  https://reviews.llvm.org/D71115/new/

https://reviews.llvm.org/D71115