Borrowck: variance analysis

gcc/rust/Make-lang.in

@@ -147,6 +147,7 @@ GRS_OBJS = \
     rust/rust-tyty-util.o \
     rust/rust-tyty-call.o \
     rust/rust-tyty-subst.o \
+    rust/rust-tyty-variance-analysis.o \
     rust/rust-typecheck-context.o \
     rust/rust-tyty-bounds.o \
     rust/rust-hir-trait-resolve.o \

gcc/rust/rust-session-manager.cc

@@ -48,6 +48,7 @@
 #include "rust-attribute-values.h"
 #include "rust-borrow-checker.h"
 #include "rust-ast-validation.h"
+#include "rust-tyty-variance-analysis.h"
 
 #include "input.h"
 #include "selftest.h"
@@ -652,6 +653,8 @@ Session::compile_crate (const char *filename)
   // type resolve
   Resolver::TypeResolution::Resolve (hir);
 
+  Resolver::TypeCheckContext::get ()->get_variance_analysis_ctx ().solve ();
+
   if (saw_errors ())
     return;
 

gcc/rust/typecheck/rust-hir-type-check-item.cc

@@ -25,6 +25,7 @@
 #include "rust-hir-trait-resolve.h"
 #include "rust-substitution-mapper.h"
 #include "rust-type-util.h"
+#include "rust-tyty-variance-analysis.h"
 
 namespace Rust {
 namespace Resolver {
@@ -204,7 +205,7 @@ TypeCheckItem::visit (HIR::TupleStruct &struct_decl)
   TyTy::ADTType::ReprOptions repr
     = parse_repr_options (attrs, struct_decl.get_locus ());
 
-  TyTy::BaseType *type = new TyTy::ADTType (
+  auto *type = new TyTy::ADTType (
     struct_decl.get_mappings ().get_hirid (), mappings->get_next_hir_id (),
     struct_decl.get_identifier ().as_string (), ident,
     TyTy::ADTType::ADTKind::TUPLE_STRUCT, std::move (variants),
@@ -215,6 +216,8 @@ TypeCheckItem::visit (HIR::TupleStruct &struct_decl)
 
   context->insert_type (struct_decl.get_mappings (), type);
   infered = type;
+
+  context->get_variance_analysis_ctx ().add_type_constraints (*type);
 }
 
 void
@@ -266,7 +269,7 @@ TypeCheckItem::visit (HIR::StructStruct &struct_decl)
   TyTy::ADTType::ReprOptions repr
     = parse_repr_options (attrs, struct_decl.get_locus ());
 
-  TyTy::BaseType *type = new TyTy::ADTType (
+  auto *type = new TyTy::ADTType (
     struct_decl.get_mappings ().get_hirid (), mappings->get_next_hir_id (),
     struct_decl.get_identifier ().as_string (), ident,
     TyTy::ADTType::ADTKind::STRUCT_STRUCT, std::move (variants),
@@ -277,6 +280,8 @@ TypeCheckItem::visit (HIR::StructStruct &struct_decl)
 
   context->insert_type (struct_decl.get_mappings (), type);
   infered = type;
+
+  context->get_variance_analysis_ctx ().add_type_constraints (*type);
 }
 
 void
@@ -307,7 +312,7 @@ TypeCheckItem::visit (HIR::Enum &enum_decl)
   RustIdent ident{*canonical_path, enum_decl.get_locus ()};
 
   // multi variant ADT
-  TyTy::BaseType *type
+  auto *type
     = new TyTy::ADTType (enum_decl.get_mappings ().get_hirid (),
 			 mappings->get_next_hir_id (),
 			 enum_decl.get_identifier ().as_string (), ident,
@@ -316,6 +321,8 @@ TypeCheckItem::visit (HIR::Enum &enum_decl)
 
   context->insert_type (enum_decl.get_mappings (), type);
   infered = type;
+
+  context->get_variance_analysis_ctx ().add_type_constraints (*type);
 }
 
 void
@@ -363,7 +370,7 @@ TypeCheckItem::visit (HIR::Union &union_decl)
 			  TyTy::VariantDef::VariantType::STRUCT, nullptr,
 			  std::move (fields)));
 
-  TyTy::BaseType *type
+  auto *type
     = new TyTy::ADTType (union_decl.get_mappings ().get_hirid (),
 			 mappings->get_next_hir_id (),
 			 union_decl.get_identifier ().as_string (), ident,
@@ -372,6 +379,8 @@ TypeCheckItem::visit (HIR::Union &union_decl)
 
   context->insert_type (union_decl.get_mappings (), type);
   infered = type;
+
+  context->get_variance_analysis_ctx ().add_type_constraints (*type);
 }
 
 void

gcc/rust/typecheck/rust-hir-type-check.h

@@ -24,6 +24,7 @@
 #include "rust-hir-trait-reference.h"
 #include "rust-autoderef.h"
 #include "rust-tyty-region.h"
+#include "rust-tyty-variance-analysis.h"
 
 #include <stack>
 
@@ -233,6 +234,8 @@ class TypeCheckContext
 
   void compute_inference_variables (bool error);
 
+  TyTy::VarianceAnalysis::CrateCtx &get_variance_analysis_ctx ();
+
 private:
   TypeCheckContext ();
 
@@ -272,6 +275,9 @@ class TypeCheckContext
   std::set<HirId> querys_in_progress;
   std::set<DefId> trait_queries_in_progress;
 
+  // variance analysis
+  TyTy::VarianceAnalysis::CrateCtx variance_analysis_ctx;
+
   /** Used to resolve (interned) lifetime names to their bounding scope. */
   class LifetimeResolver
   {

gcc/rust/typecheck/rust-typecheck-context.cc

@@ -617,6 +617,12 @@ TypeCheckContext::compute_inference_variables (bool error)
   });
 }
 
+TyTy::VarianceAnalysis::CrateCtx &
+TypeCheckContext::get_variance_analysis_ctx ()
+{
+  return variance_analysis_ctx;
+}
+
 // TypeCheckContextItem
 
 TypeCheckContextItem::Item::Item (HIR::Function *item) : item (item) {}

gcc/rust/typecheck/rust-tyty-subst.cc

@@ -589,6 +589,17 @@ SubstitutionRef::get_used_arguments () const
   return used_arguments;
 }
 
+tl::optional<SubstitutionArg>
+SubstitutionRef::get_arg_at (size_t i) const
+{
+  auto param_ty = get_substs ().at (i).get_param_ty ();
+  SubstitutionArg arg = SubstitutionArg::error ();
+  get_used_arguments ().get_argument_for_symbol (param_ty, &arg);
+  if (arg.is_error ())
+    return tl::nullopt;
+  return arg;
+}
+
 const RegionConstraints &
 SubstitutionRef::get_region_constraints () const
 {