[PATCH] D127231: Restore isa<Ty>(X) asserts inside cast<Ty>(X)

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: nikic, fhahn, lattner, bzcheeseman.
Herald added subscribers: bollu, mcrosier.
Herald added a project: All.
reames requested review of this revision.
Herald added a project: LLVM.

PLEASE DO NOT REVERT without careful consideration, and preferably prior discussion.

cast<Ty>(X) is a "checked cast".  Its entire purpose is explicitly documented (https://llvm.org/docs/ProgrammersManual.html#the-isa-cast-and-dyn-cast-templates) as catching bad casts by asserting that the cast is valid.  Unfortunately, in a recent rewrite of our casting infrastructure about three months back, these asserts got dropped.

There will shortly be a discourse post to "llvm-dev" describing the current situation in tree and the plan to address.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D127231

Files:
  llvm/include/llvm/Support/Casting.h


Index: llvm/include/llvm/Support/Casting.h
===================================================================
--- llvm/include/llvm/Support/Casting.h
+++ llvm/include/llvm/Support/Casting.h
@@ -570,21 +570,25 @@
 
 template <typename To, typename From>
 LLVM_NODISCARD inline decltype(auto) cast(const From &Val) {
+  assert(isa<To>(Val) && "cast<Ty>() argument of incompatible type!");
   return CastInfo<To, const From>::doCast(Val);
 }
 
 template <typename To, typename From>
 LLVM_NODISCARD inline decltype(auto) cast(From &Val) {
+  assert(isa<To>(Val) && "cast<Ty>() argument of incompatible type!");
   return CastInfo<To, From>::doCast(Val);
 }
 
 template <typename To, typename From>
 LLVM_NODISCARD inline decltype(auto) cast(From *Val) {
+  assert(isa<To>(Val) && "cast<Ty>() argument of incompatible type!");
   return CastInfo<To, From *>::doCast(Val);
 }
 
 template <typename To, typename From>
 LLVM_NODISCARD inline decltype(auto) cast(std::unique_ptr<From> &&Val) {
+  assert(isa<To>(Val) && "cast<Ty>() argument of incompatible type!");
   return CastInfo<To, std::unique_ptr<From>>::doCast(std::move(Val));
 }
 


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