rjmccall added a comment. In D108479#3149228 <https://reviews.llvm.org/D108479#3149228>, @samitolvanen wrote:
> I worked around this for now by explicitly allowing > `__builtin_function_start` in `CheckLValueConstantExpression`, but this seems > terribly hacky. What would be the correct way to solve this issue? Try to generalize what we do for `__builtin___CFStringMakeConstantString`. ================ Comment at: clang/lib/Sema/SemaChecking.cpp:208 + if (UnaryOp->getOpcode() == UnaryOperator::Opcode::UO_AddrOf) + E = UnaryOp->getSubExpr(); + ---------------- samitolvanen wrote: > rjmccall wrote: > > It would be more general to allow any expression that we can > > constant-evaluate to a specific function / member function reference. That > > allows callers to do stuff like `__builtin_function_start((int (A::*)() > > const) &A::x)` to resolve overloaded function references. > > > > You should delay this check if the operand is value-dependent. > > It would be more general to allow any expression that we can > > constant-evaluate to a specific function / member function reference. That > > allows callers to do stuff like `__builtin_function_start((int (A::*)() > > const) &A::x)` to resolve overloaded function references. > > I looked into using `Expr::EvaluateAsConstantExpr` here and while it works, > I'm not sure if allowing arbitrary expressions as the argument provides any > value. We can allow resolving overloaded function references without > constant-evaluating the expression (and I added tests for this). Did you have > any other use cases in mind where this might be useful? I don't see what the advantage of limiting the constant expression would be if we can constant-evaluate it. `switch` doesn't force you to make case values be integer literals and/or references to enumerators. What are you trying to achieve with a restriction? Not having arbitrary restrictions is particularly useful in C++, where templates and `constexpr` machinery can usefully do a lot of abstraction. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D108479/new/ https://reviews.llvm.org/D108479 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
