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| author | John Hodge <tpg@mutabah.net> | 2016-11-23 15:16:37 +0800 |
|---|---|---|
| committer | John Hodge <tpg@mutabah.net> | 2016-11-23 15:16:37 +0800 |
| commit | b6600a06ab403caa58a9938e677816fa5d48e1c6 (patch) | |
| tree | 5ba91ff7521604f33137e90cd5a71575a9898bf3 | |
| parent | 28b1e61bd288a0e55cc0c6cb2d6c98be6983b0a1 (diff) | |
| download | mrust-b6600a06ab403caa58a9938e677816fa5d48e1c6.tar.gz | |
HIR Typecheck Expressions - Another ivar guess rule
| -rw-r--r-- | src/hir_typeck/expr_cs.cpp | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/src/hir_typeck/expr_cs.cpp b/src/hir_typeck/expr_cs.cpp index 157ae6ae..5c06d11d 100644 --- a/src/hir_typeck/expr_cs.cpp +++ b/src/hir_typeck/expr_cs.cpp @@ -5130,6 +5130,7 @@ namespace { return context.m_ivars.types_equal(a, b); } + // TODO: `can_unsize_to` static bool can_coerce_to(const Context& context, const ::HIR::TypeRef& dst, const ::HIR::TypeRef& src) { if( dst.m_data.is_Infer() ) return false; @@ -5368,7 +5369,36 @@ namespace { return DedupKeep::Both; }); - // TODO: If there is a type that appears on both sides, pick it? + + // If there's one option for both desination types, and nothing for the source ... + if( ivar_ent.types_coerce_to.size() == 1 && ivar_ent.types_unsize_to.size() == 1 && ivar_ent.types_coerce_from.empty() && ivar_ent.types_unsize_from.empty() ) + { + // And the coercion can unsize to the unsize, pick the coercion (it's valid, the other way around isn't) + // TODO: Use a `can_unsize_to` functon instead (that handles Unsize as well as Deref) + if( H::type_derefs_from(sp, context, ivar_ent.types_unsize_to[0], ivar_ent.types_coerce_to[0]) ) + { + const auto& new_ty = ivar_ent.types_coerce_to[0]; + DEBUG("- IVar " << ty_l << " = " << new_ty << " (unsize to)"); + context.equate_types(sp, ty_l, new_ty); + ivar_ent.reset(); + return ; + } + } + #if 0 + // If there's only one coerce and unsize from, ... + if( ivar_ent.types_coerce_from.size() == 1 && ivar_ent.types_unsize_from.size() == 1 && ivar_ent.types_coerce_to.empty() && ivar_ent.types_unsize_to.empty() ) + { + // and if the coerce can unsize to the unsize target. + if( H::can_coerce_to(context, ivar_ent.types_unsize_from[0], ivar_ent.types_coerce_from[0]) ) + { + const auto& new_ty = ivar_ent.types_coerce_from[0]; + DEBUG("- IVar " << ty_l << " = " << new_ty << " (coerce from)"); + context.equate_types(sp, ty_l, new_ty); + ivar_ent.reset(); + return ; + } + } + #endif // HACK: Merge into a single lists ::std::vector< ::HIR::TypeRef> types_from_o; |