diff options
Diffstat (limited to 'src/check_decl.cpp')
| -rw-r--r-- | src/check_decl.cpp | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/src/check_decl.cpp b/src/check_decl.cpp index f9bc17ba4..193c28aea 100644 --- a/src/check_decl.cpp +++ b/src/check_decl.cpp @@ -385,7 +385,44 @@ void check_const_decl(CheckerContext *ctx, Entity *e, Ast *type_expr, Ast *init, Operand operand = {}; if (init != nullptr) { - Entity *entity = nullptr; + Entity *entity = check_entity_from_ident_or_selector(ctx, init); + if (entity != nullptr && entity->kind == Entity_TypeName) { + // NOTE(bill, 2022-02-03): This is used to solve the problem caused by type aliases + // being "confused" as constants + // + // A :: B + // C :: proc "c" (^A) + // B :: struct {x: C} + // + // A gets evaluated first, and then checks B. + // B then checks C. + // C then tries to check A which is unresolved but thought to be a constant. + // Therefore within C's check, A errs as "not a type". + // + // This is because a const declaration may or may not be a type and this cannot + // be determined from a syntactical standpoint. + // This check allows the compiler to override the entity to be checked as a type. + // + // There is no problem if B is prefixed with the `#type` helper enforcing at + // both a syntax and semantic level that B must be a type. + // + // A :: #type B + // + // This approach is not fool proof and can fail in case such as: + // + // X :: type_of(x) + // X :: Foo(int).Type + // + // Since even these kind of declarations may cause weird checking cycles. + // For the time being, these are going to be treated as an unfortunate error + // until there is a proper delaying system to try declaration again if they + // have failed. + + e->kind = Entity_TypeName; + check_type_decl(ctx, e, init, named_type); + return; + } + entity = nullptr; if (init->kind == Ast_Ident) { entity = check_ident(ctx, &operand, init, nullptr, e->type, true); } else if (init->kind == Ast_SelectorExpr) { |