https://gcc.gnu.org/g:45fc433d0fa4c447df695aae4c2f63cb428ca6b5

commit 45fc433d0fa4c447df695aae4c2f63cb428ca6b5
Author: Philip Herron <herron.phi...@googlemail.com>
Date:   Thu Feb 13 17:01:31 2025 +0000

    gccrs: fix name resolution for generics where type param is declared later
    
    Rust allows you to use generics within type bounds when they are declared
    later on. This changes the name resolution to walk the genric params
    in two passes to ensure the type parameters are setup before drilling down
    into the type parameters
    
    This issue has exposed another type checking issue which needs fixed in
    a subseqent patch.
    
    Addresses Rust-GCC#3022
    
    gcc/rust/ChangeLog:
    
            * resolve/rust-ast-resolve-item.cc (ResolveTraitItems::visit): use 
new api
            (ResolveItem::visit): likewise
            (ResolveExternItem::visit): likewise
            * resolve/rust-ast-resolve-stmt.h: likewise
            * resolve/rust-ast-resolve-type.h (class ResolveGenericParam): 
remove
            (class ResolveGenericParams): added new api
    
    Signed-off-by: Philip Herron <herron.phi...@googlemail.com>

Diff:
---
 gcc/rust/resolve/rust-ast-resolve-item.cc | 48 ++++++++---------
 gcc/rust/resolve/rust-ast-resolve-stmt.h  | 26 ++++-----
 gcc/rust/resolve/rust-ast-resolve-type.h  | 87 ++++++++++++++++++-------------
 3 files changed, 86 insertions(+), 75 deletions(-)

diff --git a/gcc/rust/resolve/rust-ast-resolve-item.cc 
b/gcc/rust/resolve/rust-ast-resolve-item.cc
index b50c158a7a77..c96da3da3f13 100644
--- a/gcc/rust/resolve/rust-ast-resolve-item.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-item.cc
@@ -64,8 +64,8 @@ ResolveTraitItems::visit (AST::Function &function)
   resolver->push_new_label_rib (resolver->get_label_scope ().peek ());
 
   if (function.has_generics ())
-    for (auto &generic : function.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (function.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (function.has_return_type ())
     ResolveType::go (function.get_return_type ());
@@ -188,8 +188,8 @@ ResolveItem::visit (AST::TypeAlias &alias)
   resolver->get_type_scope ().push (scope_node_id);
 
   if (alias.has_generics ())
-    for (auto &generic : alias.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (alias.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (alias.has_where_clause ())
     ResolveWhereClause::Resolve (alias.get_where_clause ());
@@ -250,8 +250,8 @@ ResolveItem::visit (AST::TupleStruct &struct_decl)
   resolver->get_type_scope ().push (scope_node_id);
 
   if (struct_decl.has_generics ())
-    for (auto &generic : struct_decl.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (struct_decl.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (struct_decl.has_where_clause ())
     ResolveWhereClause::Resolve (struct_decl.get_where_clause ());
@@ -284,8 +284,8 @@ ResolveItem::visit (AST::Enum &enum_decl)
   resolver->get_type_scope ().push (scope_node_id);
 
   if (enum_decl.has_generics ())
-    for (auto &generic : enum_decl.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, cpath);
+    ResolveGenericParams::go (enum_decl.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (enum_decl.has_where_clause ())
     ResolveWhereClause::Resolve (enum_decl.get_where_clause ());
@@ -374,8 +374,8 @@ ResolveItem::visit (AST::StructStruct &struct_decl)
   resolver->get_type_scope ().push (scope_node_id);
 
   if (struct_decl.has_generics ())
-    for (auto &generic : struct_decl.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (struct_decl.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (struct_decl.has_where_clause ())
     ResolveWhereClause::Resolve (struct_decl.get_where_clause ());
@@ -409,8 +409,8 @@ ResolveItem::visit (AST::Union &union_decl)
   resolver->get_type_scope ().push (scope_node_id);
 
   if (union_decl.has_generics ())
-    for (auto &generic : union_decl.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (union_decl.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (union_decl.has_where_clause ())
     ResolveWhereClause::Resolve (union_decl.get_where_clause ());
@@ -476,8 +476,8 @@ ResolveItem::visit (AST::Function &function)
   resolver->push_new_label_rib (resolver->get_label_scope ().peek ());
 
   if (function.has_generics ())
-    for (auto &generic : function.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (function.get_generic_params (), prefix,
+                             canonical_prefix);
 
   // resolve any where clause items
   if (function.has_where_clause ())
@@ -567,8 +567,8 @@ ResolveItem::visit (AST::InherentImpl &impl_block)
   resolve_visibility (impl_block.get_visibility ());
 
   if (impl_block.has_generics ())
-    for (auto &generic : impl_block.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (impl_block.get_generic_params (), prefix,
+                             canonical_prefix);
 
   // resolve any where clause items
   if (impl_block.has_where_clause ())
@@ -651,8 +651,8 @@ ResolveItem::visit (AST::TraitImpl &impl_block)
   resolver->push_new_label_rib (resolver->get_label_scope ().peek ());
 
   if (impl_block.has_generics ())
-    for (auto &generic : impl_block.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (impl_block.get_generic_params (), prefix,
+                             canonical_prefix);
 
   // resolve any where clause items
   if (impl_block.has_where_clause ())
@@ -776,10 +776,10 @@ ResolveItem::visit (AST::Trait &trait)
   resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
   resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
 
-  ResolveGenericParam::go (trait.get_implicit_self (), prefix,
-                          canonical_prefix);
-  for (auto &generic : trait.get_generic_params ())
-    ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+  ResolveGenericParams::go_single (trait.get_implicit_self (), prefix,
+                                  canonical_prefix);
+  ResolveGenericParams::go (trait.get_generic_params (), prefix,
+                           canonical_prefix);
 
   // Self is an implicit TypeParam so lets mark it as such
   resolver->get_type_scope ().append_reference_for_def (
@@ -1044,8 +1044,8 @@ ResolveExternItem::visit (AST::Function &function)
 
   // resolve the generics
   if (function.has_generics ())
-    for (auto &generic : function.get_generic_params ())
-      ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+    ResolveGenericParams::go (function.get_generic_params (), prefix,
+                             canonical_prefix);
 
   if (function.has_return_type ())
     ResolveType::go (function.get_return_type ());
diff --git a/gcc/rust/resolve/rust-ast-resolve-stmt.h 
b/gcc/rust/resolve/rust-ast-resolve-stmt.h
index 700adddcb40e..da2bb155cdb1 100644
--- a/gcc/rust/resolve/rust-ast-resolve-stmt.h
+++ b/gcc/rust/resolve/rust-ast-resolve-stmt.h
@@ -104,10 +104,8 @@ public:
     resolver->get_type_scope ().push (scope_node_id);
 
     if (struct_decl.has_generics ())
-      {
-       for (auto &generic : struct_decl.get_generic_params ())
-         ResolveGenericParam::go (*generic, prefix, canonical_prefix);
-      }
+      ResolveGenericParams::go (struct_decl.get_generic_params (), prefix,
+                               canonical_prefix);
 
     for (AST::TupleField &field : struct_decl.get_fields ())
       ResolveType::go (field.get_field_type ());
@@ -137,10 +135,8 @@ public:
     resolver->get_type_scope ().push (scope_node_id);
 
     if (enum_decl.has_generics ())
-      {
-       for (auto &generic : enum_decl.get_generic_params ())
-         ResolveGenericParam::go (*generic, prefix, canonical_prefix);
-      }
+      ResolveGenericParams::go (enum_decl.get_generic_params (), prefix,
+                               canonical_prefix);
 
     for (auto &variant : enum_decl.get_variants ())
       ResolveStmt::go (*variant, path, canonical_prefix, path);
@@ -262,10 +258,8 @@ public:
     resolver->get_type_scope ().push (scope_node_id);
 
     if (struct_decl.has_generics ())
-      {
-       for (auto &generic : struct_decl.get_generic_params ())
-         ResolveGenericParam::go (*generic, prefix, canonical_prefix);
-      }
+      ResolveGenericParams::go (struct_decl.get_generic_params (), prefix,
+                               canonical_prefix);
 
     for (AST::StructField &field : struct_decl.get_fields ())
       {
@@ -300,8 +294,8 @@ public:
     resolver->get_type_scope ().push (scope_node_id);
 
     if (union_decl.has_generics ())
-      for (auto &generic : union_decl.get_generic_params ())
-       ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+      ResolveGenericParams::go (union_decl.get_generic_params (), prefix,
+                               canonical_prefix);
 
     for (AST::StructField &field : union_decl.get_variants ())
       {
@@ -341,8 +335,8 @@ public:
     resolver->push_new_label_rib (resolver->get_label_scope ().peek ());
 
     if (function.has_generics ())
-      for (auto &generic : function.get_generic_params ())
-       ResolveGenericParam::go (*generic, prefix, canonical_prefix);
+      ResolveGenericParams::go (function.get_generic_params (), prefix,
+                               canonical_prefix);
 
     if (function.has_return_type ())
       ResolveType::go (function.get_return_type ());
diff --git a/gcc/rust/resolve/rust-ast-resolve-type.h 
b/gcc/rust/resolve/rust-ast-resolve-type.h
index 5870aca15dc1..38581440b236 100644
--- a/gcc/rust/resolve/rust-ast-resolve-type.h
+++ b/gcc/rust/resolve/rust-ast-resolve-type.h
@@ -142,66 +142,83 @@ private:
   ResolveTypeBound () : ResolverBase () {}
 };
 
-class ResolveGenericParam : public ResolverBase
+class ResolveGenericParams : public ResolverBase
 {
   using Rust::Resolver::ResolverBase::visit;
 
 public:
-  static NodeId go (AST::GenericParam &param, const CanonicalPath &prefix,
-                   const CanonicalPath &canonical_prefix)
+  static void go (std::vector<std::unique_ptr<AST::GenericParam>> &params,
+                 const CanonicalPath &prefix,
+                 const CanonicalPath &canonical_prefix)
   {
-    ResolveGenericParam resolver (prefix, canonical_prefix);
+    ResolveGenericParams resolver (prefix, canonical_prefix);
+
+    // this needs to be done in two phases as they can be used and defined 
later
+    // in bounds
+    for (auto &param : params)
+      param->accept_vis (resolver);
+
+    resolver.first_pass = false;
+
+    for (auto &param : params)
+      param->accept_vis (resolver);
+  }
+
+  static void go_single (AST::GenericParam &param, const CanonicalPath &prefix,
+                        const CanonicalPath &canonical_prefix)
+  {
+    ResolveGenericParams resolver (prefix, canonical_prefix);
+
+    param.accept_vis (resolver);
+    resolver.first_pass = false;
     param.accept_vis (resolver);
-    return resolver.resolved_node;
   }
 
   void visit (AST::ConstGenericParam &param) override
   {
-    ResolveType::go (param.get_type ());
-
-    if (param.has_default_value ())
+    if (first_pass)
+      ResolveType::go (param.get_type ());
+    else if (param.has_default_value ())
       ResolveExpr::go (param.get_default_value ().get_expression (), prefix,
                       canonical_prefix);
-
-    ok = true;
   }
 
   void visit (AST::TypeParam &param) override
   {
-    // if it has a type lets resolve it
-    if (param.has_type ())
-      ResolveType::go (param.get_type ());
-
-    if (param.has_type_param_bounds ())
+    if (first_pass)
+      {
+       // if it has a type lets resolve it
+       if (param.has_type ())
+         ResolveType::go (param.get_type ());
+
+       auto seg = CanonicalPath::new_seg (
+         param.get_node_id (), param.get_type_representation ().as_string ());
+       resolver->get_type_scope ().insert (
+         seg, param.get_node_id (), param.get_locus (), false,
+         Rib::ItemType::Type,
+         [&] (const CanonicalPath &, NodeId, location_t locus) -> void {
+           rust_error_at (param.get_locus (),
+                          "generic param redefined multiple times");
+           rust_error_at (locus, "was defined here");
+         });
+
+       mappings.insert_canonical_path (param.get_node_id (), seg);
+      }
+    else if (param.has_type_param_bounds ())
       {
        for (auto &bound : param.get_type_param_bounds ())
-         {
-           ResolveTypeBound::go (*bound);
-         }
+         ResolveTypeBound::go (*bound);
       }
-
-    auto seg
-      = CanonicalPath::new_seg (param.get_node_id (),
-                               param.get_type_representation ().as_string ());
-    resolver->get_type_scope ().insert (
-      seg, param.get_node_id (), param.get_locus (), false, 
Rib::ItemType::Type,
-      [&] (const CanonicalPath &, NodeId, location_t locus) -> void {
-       rust_error_at (param.get_locus (),
-                      "generic param redefined multiple times");
-       rust_error_at (locus, "was defined here");
-      });
-
-    mappings.insert_canonical_path (param.get_node_id (), seg);
   }
 
 private:
-  ResolveGenericParam (const CanonicalPath &prefix,
-                      const CanonicalPath &canonical_prefix)
-    : ResolverBase (), ok (false), prefix (prefix),
+  ResolveGenericParams (const CanonicalPath &prefix,
+                       const CanonicalPath &canonical_prefix)
+    : ResolverBase (), first_pass (true), prefix (prefix),
       canonical_prefix (canonical_prefix)
   {}
 
-  bool ok;
+  bool first_pass;
   const CanonicalPath &prefix;
   const CanonicalPath &canonical_prefix;
 };

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