[constexpr][c++2a] Try-catch blocks in constexpr functions

Implement support for try-catch blocks in constexpr functions, as
proposed in http://wg21.link/P1002 and voted in San Diego for c++20.

The idea is that we can still never throw inside constexpr, so the catch
block is never entered. A try-catch block like this:

try { f(); } catch (...) { }

is then morally equivalent to just

{ f(); }

Same idea should apply for function/constructor try blocks.

rdar://problem/45530773

Differential Revision: https://reviews.llvm.org/D55097

llvm-svn: 348789
7 files changed
tree: 2d2023d622de2909cb5a1ca81557d9b47bbe0f83
  1. clang/
  2. clang-tools-extra/
  3. compiler-rt/
  4. debuginfo-tests/
  5. libclc/
  6. libcxx/
  7. libcxxabi/
  8. libunwind/
  9. lld/
  10. lldb/
  11. llgo/
  12. llvm/
  13. openmp/
  14. parallel-libs/
  15. polly/
  16. README.md
README.md

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