[PATCH] D105997: Implement _ExtInt conversion rules

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman created this revision.
aaron.ballman added reviewers: rsmith, erichkeane, mibintc, jyknight, rjmccall.
aaron.ballman requested review of this revision.
Herald added a project: clang.

Clang implemented the _ExtInt datatype as a bit-precise integer type, which was then proposed to WG14. WG14 has accepted the proposal (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2709.pdf), but Clang requires some additional work as a result.

In the original Clang implementation, we elected to disallow implicit conversions involving these types until after WG14 finalized the rules. This patch implements the rules decided by WG14: no integer promotion for bit-precise types, conversions prefer the larger of the two types and in the event of a tie (say `_ExtInt(32)` and a 32-bit `int`), the standard type wins.

There are more changes still needed to conform to N2709, but those will be handled in follow-up patches.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105997

Files:
  clang/lib/Sema/SemaExpr.cpp
  clang/test/Sema/ext-int.c
  clang/test/SemaCXX/ext-int.cpp

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