HIR Typecheck Expr - (minor) Commenting and debug in tracking box inferrence failure

2 files changed, 13 insertions, 5 deletions

diff --git a/src/hir_typeck/expr_cs.cpp b/src/hir_typeck/expr_cs.cpp
index 529a2366..2cfd6fc4 100644
--- a/src/hir_typeck/expr_cs.cpp
+++ b/src/hir_typeck/expr_cs.cpp
@@ -3329,13 +3329,22 @@ namespace {
         
         // CoerceUnsized trait
         // - Only valid for generic or path destination types
-        if( ty_dst.m_data.is_Generic() || ty_dst.m_data.is_Path() ) {
-            
+        if( ty_dst.m_data.is_Generic() || ty_dst.m_data.is_Path() )
+        {
             const auto& lang_CoerceUnsized = context.m_crate.get_lang_item_path(sp, "coerce_unsized");
+            
             ::HIR::PathParams   pp;
             pp.m_types.push_back( ty_dst.clone() );
+            
+            // PROBLEM: In the desugaring of `box`, it's required that the container type propagate backwards through the coercion point
+            // - However, there's still a coercion point that needs to apply to the contained type.
+            // - `let foo: Box<[i32]> = box [1, 2, 3];`
+            // - Special-casing `Box` here could work (assuming that Box can only coerce to Box, and applying unsizing coercion rules to the inner)
+            
+            //bool fuzzy_match = false;
             bool found = context.m_resolve.find_trait_impls(sp, lang_CoerceUnsized, pp, ty_src, [&](auto impl, auto cmp) {
-                // TODO: Allow fuzzy match if only match
+                // TODO: Allow fuzzy match if it's the only matching possibility
+                DEBUG("[check_coerce] cmp=" << cmp << ", impl=" << impl);
                 return cmp == ::HIR::Compare::Equal;
                 });
             if( found )
diff --git a/src/hir_typeck/helpers.cpp b/src/hir_typeck/helpers.cpp
index 8f98f676..b35d6438 100644
--- a/src/hir_typeck/helpers.cpp
+++ b/src/hir_typeck/helpers.cpp
@@ -932,7 +932,7 @@ bool TraitResolution::find_trait_impls(const Span& sp,
     static ::std::map< ::std::string, ::HIR::TypeRef>    null_assoc;
 
     const auto& type = this->m_ivars.get_type(ty);
-    TRACE_FUNCTION_F("trait = " << trait << ", type = " << type);
+    TRACE_FUNCTION_F("trait = " << trait << params  << ", type = " << type);
     
     if( trait == this->m_crate.get_lang_item_path(sp, "sized") ) {
         TU_MATCH_DEF(::HIR::TypeRef::Data, (type.m_data), (e),
@@ -1741,7 +1741,6 @@ bool TraitResolution::find_trait_impls_bound(const Span& sp, const ::HIR::Simple
     return this->iterate_bounds([&](const auto& b) {
         TU_IFLET(::HIR::GenericBound, b, TraitBound, e,
             const auto& b_params = e.trait.m_path.m_params;
-            DEBUG("(bound) - " << e.type << " : " << e.trait);
             // TODO: Allow fuzzy equality?
             if( e.type == type )
             {