Summary: C++1z 6.4.1/p2: If the if statement is of the form if constexpr, the value of the condition shall be a contextually converted constant expression of type bool [...] C++1z 5.20/p4: [...] A contextually converted constant expression of type bool is an expression, contextually converted to bool (Clause4), where the converted expression is a constant expression and the conversion sequence contains only the conversions above. [...] Contextually converting result of an expression `e` to a Boolean value requires `bool t(e)` to be well-formed. An explicit conversion function is only considered as a user-defined conversion for direct-initialization, which is essentially what //contextually converted to bool// requires. Also, fixes PR28470. Reviewers: rsmith Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D24158 llvm-svn: 280838 |
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| .. | ||
| basic | ||
| class | ||
| class.access | ||
| class.derived | ||
| concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept | ||
| conv | ||
| dcl.dcl | ||
| dcl.decl | ||
| drs | ||
| except | ||
| expr | ||
| lex | ||
| over | ||
| special | ||
| stmt.stmt | ||
| temp | ||