From 418bad939abf464ac03dab0c9044316aa4c33f95 Mon Sep 17 00:00:00 2001
From: Prabhat Sachdeva <prabhatexit0@gmail.com>
Date: Fri, 21 Jul 2023 06:48:18 +0530
Subject: [PATCH] Add name resolution information to trace stream (#2986)

Adds the following information about name resolution to the trace
output:
* Name resolution process
```
** resolving stmt | decl `<stmt | decl>` (<source_location>)
   ...
** finished resolving stmt | decl `<stmt | decl>` (<source_location>)
```
* When a name is added to the static scope
```
--- declared `<name>` as `<entity>` in `<scope>` (<source_location>)
```
* When a name is resolved
```
--- resolved `<name>` as `<result>` in `<scope>` (<source_location>)
```
* Marking a name declared/usable
```
--- marked `<name>` <usable | declared but not usable> in `<scope>`
```
---
 explorer/ast/BUILD                        |   2 +
 explorer/ast/static_scope.cpp             |  42 +++
 explorer/ast/static_scope.h               |  21 +-
 explorer/interpreter/BUILD                |   1 +
 explorer/interpreter/exec_program.cpp     |   2 +-
 explorer/interpreter/resolve_names.cpp    |  75 +++--
 explorer/interpreter/resolve_names.h      |   4 +-
 explorer/trace_testdata/full_trace.carbon | 347 +++++++++++++++++++---
 8 files changed, 435 insertions(+), 59 deletions(-)

diff --git a/explorer/ast/BUILD b/explorer/ast/BUILD
index 0fecb13ec634..cd2dfad2acc3 100644
--- a/explorer/ast/BUILD
+++ b/explorer/ast/BUILD
@@ -147,9 +147,11 @@ cc_library(
         ":ast",
         "//common:check",
         "//common:error",
+        "//common:ostream",
         "//explorer/common:error_builders",
         "//explorer/common:nonnull",
         "//explorer/common:source_location",
+        "//explorer/common:trace_stream",
         "@llvm-project//llvm:Support",
     ],
 )
diff --git a/explorer/ast/static_scope.cpp b/explorer/ast/static_scope.cpp
index 2e0a5b043047..c1910db6965f 100644
--- a/explorer/ast/static_scope.cpp
+++ b/explorer/ast/static_scope.cpp
@@ -6,7 +6,9 @@
 
 #include <optional>
 
+#include "common/ostream.h"
 #include "explorer/common/error_builders.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/Error.h"
 
 namespace Carbon {
@@ -23,15 +25,42 @@ auto StaticScope::Add(std::string_view name, ValueNodeView entity,
     if (static_cast<int>(status) > static_cast<int>(it->second.status)) {
       it->second.status = status;
     }
+  } else {
+    if (trace_stream_->is_enabled()) {
+      *trace_stream_ << "--- declared `" << name << "` as `" << entity
+                     << "` in `" << PrintAsID(*this) << "` ("
+                     << entity.base().source_loc() << ")\n";
+    }
   }
   return Success();
 }
 
+void StaticScope::Print(llvm::raw_ostream& out) const {
+  if (ast_node_) {
+    ast_node_.value()->Print(out);
+  } else {
+    *trace_stream_ << "package";
+  }
+}
+
+void StaticScope::PrintID(llvm::raw_ostream& out) const {
+  if (ast_node_) {
+    ast_node_.value()->PrintID(out);
+  } else {
+    *trace_stream_ << "package";
+  }
+}
+
 void StaticScope::MarkDeclared(std::string_view name) {
   auto it = declared_names_.find(name);
   CARBON_CHECK(it != declared_names_.end()) << name << " not found";
   if (it->second.status == NameStatus::KnownButNotDeclared) {
     it->second.status = NameStatus::DeclaredButNotUsable;
+    if (trace_stream_->is_enabled()) {
+      *trace_stream_ << "--- marked `" << name
+                     << "` declared but not usable in `" << PrintAsID(*this)
+                     << "`\n";
+    }
   }
 }
 
@@ -39,6 +68,10 @@ void StaticScope::MarkUsable(std::string_view name) {
   auto it = declared_names_.find(name);
   CARBON_CHECK(it != declared_names_.end()) << name << " not found";
   it->second.status = NameStatus::Usable;
+  if (trace_stream_->is_enabled()) {
+    *trace_stream_ << "--- marked `" << name << "` usable in `"
+                   << PrintAsID(*this) << "`\n";
+  }
 }
 
 auto StaticScope::Resolve(std::string_view name,
@@ -94,6 +127,15 @@ auto StaticScope::TryResolveHere(std::string_view name,
   if (it == declared_names_.end()) {
     return {std::nullopt};
   }
+
+  auto exit_scope_function = llvm::make_scope_exit([&]() {
+    if (trace_stream_->is_enabled()) {
+      *trace_stream_ << "--- resolved `" << name << "` as `"
+                     << it->second.entity << "` in `" << PrintAsID(*this)
+                     << "` (" << source_loc << ")\n";
+    }
+  });
+
   if (allow_undeclared) {
     return {it->second.entity};
   }
diff --git a/explorer/ast/static_scope.h b/explorer/ast/static_scope.h
index 79da6b2e86a3..746807c38825 100644
--- a/explorer/ast/static_scope.h
+++ b/explorer/ast/static_scope.h
@@ -12,6 +12,7 @@
 #include "explorer/ast/value_node.h"
 #include "explorer/common/nonnull.h"
 #include "explorer/common/source_location.h"
+#include "explorer/common/trace_stream.h"
 #include "llvm/ADT/StringMap.h"
 
 namespace Carbon {
@@ -35,11 +36,17 @@ class StaticScope {
   };
 
   // Construct a root scope.
-  StaticScope() = default;
+  explicit StaticScope(Nonnull<TraceStream*> trace_stream)
+      : ast_node_(std::nullopt), trace_stream_(trace_stream) {}
 
   // Construct a scope that is nested within the given scope.
-  explicit StaticScope(Nonnull<const StaticScope*> parent)
-      : parent_scope_(parent) {}
+  explicit StaticScope(Nonnull<const StaticScope*> parent,
+                       std::optional<Nonnull<const AstNode*>> ast_node)
+      : parent_scope_(parent),
+        ast_node_(ast_node),
+        trace_stream_(parent->trace_stream_) {}
+
+  StaticScope() = default;
 
   // Defines `name` to be `entity` in this scope, or reports a compilation error
   // if `name` is already defined to be a different entity in this scope.
@@ -48,6 +55,10 @@ class StaticScope {
   auto Add(std::string_view name, ValueNodeView entity,
            NameStatus status = NameStatus::Usable) -> ErrorOr<Success>;
 
+  void Print(llvm::raw_ostream& out) const;
+
+  void PrintID(llvm::raw_ostream& out) const;
+
   // Marks `name` as being past its point of declaration.
   void MarkDeclared(std::string_view name);
   // Marks `name` as being completely declared and hence usable.
@@ -102,6 +113,10 @@ class StaticScope {
 
   // Stores the value node of the BindingPattern of the returned var definition.
   std::optional<ValueNodeView> returned_var_def_view_;
+
+  std::optional<Nonnull<const AstNode*>> ast_node_;
+
+  Nonnull<TraceStream*> trace_stream_;
 };
 
 }  // namespace Carbon
diff --git a/explorer/interpreter/BUILD b/explorer/interpreter/BUILD
index 94102e9ec057..b2ec4791c7a2 100644
--- a/explorer/interpreter/BUILD
+++ b/explorer/interpreter/BUILD
@@ -152,6 +152,7 @@ cc_library(
         "//explorer/ast",
         "//explorer/ast:static_scope",
         "//explorer/common:arena",
+        "//explorer/common:trace_stream",
         "@llvm-project//llvm:Support",
     ],
 )
diff --git a/explorer/interpreter/exec_program.cpp b/explorer/interpreter/exec_program.cpp
index debecefc725a..3b066a3d010c 100644
--- a/explorer/interpreter/exec_program.cpp
+++ b/explorer/interpreter/exec_program.cpp
@@ -45,7 +45,7 @@ auto AnalyzeProgram(Nonnull<Arena*> arena, AST ast,
   if (trace_stream->is_enabled()) {
     *trace_stream << "********** resolving names **********\n";
   }
-  CARBON_RETURN_IF_ERROR(ResolveNames(ast));
+  CARBON_RETURN_IF_ERROR(ResolveNames(ast, trace_stream));
 
   set_prog_phase.update_phase(ProgramPhase::ControlFlowResolution);
   if (trace_stream->is_enabled()) {
diff --git a/explorer/interpreter/resolve_names.cpp b/explorer/interpreter/resolve_names.cpp
index b7b6d7b556a9..6897b8129ebd 100644
--- a/explorer/interpreter/resolve_names.cpp
+++ b/explorer/interpreter/resolve_names.cpp
@@ -39,6 +39,8 @@ namespace {
 // bodies.
 class NameResolver {
  public:
+  explicit NameResolver(Nonnull<TraceStream*> trace_stream)
+      : trace_stream_(trace_stream) {}
   enum class ResolveFunctionBodies {
     // Do not resolve names in function bodies.
     Skip,
@@ -122,6 +124,8 @@ class NameResolver {
 
   // Mapping from declarations to the scope in which they expose a name.
   llvm::DenseMap<const Declaration*, StaticScope*> exposed_name_scopes_;
+
+  Nonnull<TraceStream*> trace_stream_;
 };
 
 }  // namespace
@@ -132,6 +136,7 @@ auto NameResolver::ResolveQualifier(DeclaredName name,
     -> ErrorOr<Nonnull<StaticScope*>> {
   Nonnull<StaticScope*> scope = &enclosing_scope;
   std::optional<ValueNodeView> scope_node;
+
   for (const auto& [loc, qualifier] : name.qualifiers()) {
     // TODO: If we permit qualified names anywhere other than the top level, we
     // will need to decide whether the first name in the qualifier is looked up
@@ -164,9 +169,9 @@ auto NameResolver::AddExposedName(DeclaredName name, ValueNodeView value,
   // We are just collecting names at this stage, so nothing is marked as
   // declared yet. Therefore we don't complain if the qualifier contains a
   // known but not declared namespace name.
-  CARBON_ASSIGN_OR_RETURN(
-      Nonnull<StaticScope*> scope,
-      ResolveQualifier(name, enclosing_scope, /*allow_undeclared=*/true));
+  CARBON_ASSIGN_OR_RETURN(Nonnull<StaticScope*> scope,
+                          ResolveQualifier(name, enclosing_scope,
+                                           /*allow_undeclared=*/true));
   CARBON_RETURN_IF_ERROR(scope->Add(
       name.inner_name(), value, StaticScope::NameStatus::KnownButNotDeclared));
   return scope;
@@ -183,7 +188,7 @@ auto NameResolver::AddExposedNames(const Declaration& declaration,
           Nonnull<StaticScope*> scope,
           AddExposedName(namespace_decl.name(), &namespace_decl,
                          enclosing_scope, allow_qualified_names));
-      namespace_scopes_.try_emplace(&namespace_decl, scope);
+      namespace_scopes_.try_emplace(&namespace_decl, scope, &namespace_decl);
       break;
     }
     case DeclarationKind::InterfaceDeclaration:
@@ -426,7 +431,7 @@ auto NameResolver::ResolveNamesImpl(Expression& expression,
             &cast<GenericBinding>(enclosing_dot_self->base()));
       }
       // Introduce `.Self` into scope on the right of the `where` keyword.
-      StaticScope where_scope(&enclosing_scope);
+      StaticScope where_scope(&enclosing_scope, &where);
       CARBON_RETURN_IF_ERROR(where_scope.Add(".Self", &where.self_binding()));
       for (Nonnull<WhereClause*> clause : where.clauses()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(*clause, where_scope));
@@ -458,6 +463,7 @@ auto NameResolver::ResolveNamesImpl(Expression& expression,
     case ExpressionKind::UnimplementedExpression:
       return ProgramError(expression.source_loc()) << "Unimplemented";
   }
+
   return {std::nullopt};
 }
 
@@ -495,6 +501,7 @@ auto NameResolver::ResolveNamesImpl(WhereClause& clause,
       break;
     }
   }
+
   return Success();
 }
 
@@ -519,7 +526,7 @@ auto NameResolver::ResolveNamesImpl(Pattern& pattern,
     case PatternKind::GenericBinding: {
       auto& binding = cast<GenericBinding>(pattern);
       // `.Self` is in scope in the context of the type.
-      StaticScope self_scope(&enclosing_scope);
+      StaticScope self_scope(&enclosing_scope, &binding);
       CARBON_RETURN_IF_ERROR(self_scope.Add(".Self", &binding));
       CARBON_RETURN_IF_ERROR(ResolveNames(binding.type(), self_scope));
       if (binding.name() != AnonymousName) {
@@ -555,6 +562,7 @@ auto NameResolver::ResolveNamesImpl(Pattern& pattern,
           ResolveNames(cast<AddrPattern>(pattern).binding(), enclosing_scope));
       break;
   }
+
   return Success();
 }
 
@@ -568,6 +576,10 @@ auto NameResolver::ResolveNames(Statement& statement,
 auto NameResolver::ResolveNamesImpl(Statement& statement,
                                     StaticScope& enclosing_scope)
     -> ErrorOr<Success> {
+  if (trace_stream_->is_enabled()) {
+    *trace_stream_ << "** resolving stmt `" << PrintAsID(statement) << "` ("
+                   << statement.source_loc() << ")\n";
+  }
   switch (statement.kind()) {
     case StatementKind::ExpressionStatement:
       CARBON_RETURN_IF_ERROR(ResolveNames(
@@ -638,7 +650,7 @@ auto NameResolver::ResolveNamesImpl(Statement& statement,
     }
     case StatementKind::Block: {
       auto& block = cast<Block>(statement);
-      StaticScope block_scope(&enclosing_scope);
+      StaticScope block_scope(&enclosing_scope, &block);
       for (Nonnull<Statement*> sub_statement : block.statements()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(*sub_statement, block_scope));
       }
@@ -652,8 +664,8 @@ auto NameResolver::ResolveNamesImpl(Statement& statement,
       break;
     }
     case StatementKind::For: {
-      StaticScope statement_scope(&enclosing_scope);
       auto& for_stmt = cast<For>(statement);
+      StaticScope statement_scope(&enclosing_scope, &for_stmt);
       CARBON_RETURN_IF_ERROR(
           ResolveNames(for_stmt.loop_target(), statement_scope));
       CARBON_RETURN_IF_ERROR(
@@ -666,7 +678,7 @@ auto NameResolver::ResolveNamesImpl(Statement& statement,
       auto& match = cast<Match>(statement);
       CARBON_RETURN_IF_ERROR(ResolveNames(match.expression(), enclosing_scope));
       for (Match::Clause& clause : match.clauses()) {
-        StaticScope clause_scope(&enclosing_scope);
+        StaticScope clause_scope(&enclosing_scope, &clause.statement());
         CARBON_RETURN_IF_ERROR(ResolveNames(clause.pattern(), clause_scope));
         CARBON_RETURN_IF_ERROR(ResolveNames(clause.statement(), clause_scope));
       }
@@ -676,6 +688,13 @@ auto NameResolver::ResolveNamesImpl(Statement& statement,
     case StatementKind::Continue:
       break;
   }
+
+  if (trace_stream_->is_enabled()) {
+    *trace_stream_ << "** finished resolving stmt `";
+    statement.PrintID(trace_stream_->stream());
+    *trace_stream_ << "` (" << statement.source_loc() << ")\n";
+  }
+
   return Success();
 }
 
@@ -712,6 +731,12 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
                                     StaticScope& enclosing_scope,
                                     ResolveFunctionBodies bodies)
     -> ErrorOr<Success> {
+  if (trace_stream_->is_enabled()) {
+    *trace_stream_ << "** resolving decl `";
+    declaration.PrintID(trace_stream_->stream());
+    *trace_stream_ << "` (" << declaration.source_loc() << ")\n";
+  }
+
   switch (declaration.kind()) {
     case DeclarationKind::NamespaceDeclaration: {
       auto& namespace_decl = cast<NamespaceDeclaration>(declaration);
@@ -726,7 +751,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
       auto& iface = cast<ConstraintTypeDeclaration>(declaration);
       CARBON_ASSIGN_OR_RETURN(Nonnull<StaticScope*> scope,
                               ResolveQualifier(iface.name(), enclosing_scope));
-      StaticScope iface_scope(scope);
+      StaticScope iface_scope(scope, &iface);
       scope->MarkDeclared(iface.name().inner_name());
       if (auto params = iface.params()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(**params, iface_scope));
@@ -741,7 +766,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
     }
     case DeclarationKind::ImplDeclaration: {
       auto& impl = cast<ImplDeclaration>(declaration);
-      StaticScope impl_scope(&enclosing_scope);
+      StaticScope impl_scope(&enclosing_scope, &impl);
       for (Nonnull<GenericBinding*> binding : impl.deduced_parameters()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(binding->type(), impl_scope));
         CARBON_RETURN_IF_ERROR(impl_scope.Add(binding->name(), binding));
@@ -778,7 +803,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
               : DeclaredName(function.source_loc(), "destructor");
       CARBON_ASSIGN_OR_RETURN(Nonnull<StaticScope*> scope,
                               ResolveQualifier(name, enclosing_scope));
-      StaticScope function_scope(scope);
+      StaticScope function_scope(scope, &function);
       scope->MarkDeclared(name.inner_name());
       for (Nonnull<GenericBinding*> binding : function.deduced_parameters()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(*binding, function_scope));
@@ -805,7 +830,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
       CARBON_ASSIGN_OR_RETURN(
           Nonnull<StaticScope*> scope,
           ResolveQualifier(class_decl.name(), enclosing_scope));
-      StaticScope class_scope(scope);
+      StaticScope class_scope(scope, &class_decl);
       scope->MarkDeclared(class_decl.name().inner_name());
       if (auto type_params = class_decl.type_params()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(**type_params, class_scope));
@@ -827,7 +852,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
       CARBON_ASSIGN_OR_RETURN(
           Nonnull<StaticScope*> scope,
           ResolveQualifier(mixin_decl.name(), enclosing_scope));
-      StaticScope mixin_scope(scope);
+      StaticScope mixin_scope(scope, &mixin_decl);
       scope->MarkDeclared(mixin_decl.name().inner_name());
       if (auto params = mixin_decl.params()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(**params, mixin_scope));
@@ -847,7 +872,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
       auto& choice = cast<ChoiceDeclaration>(declaration);
       CARBON_ASSIGN_OR_RETURN(Nonnull<StaticScope*> scope,
                               ResolveQualifier(choice.name(), enclosing_scope));
-      StaticScope choice_scope(scope);
+      StaticScope choice_scope(scope, &choice);
       scope->MarkDeclared(choice.name().inner_name());
       if (auto type_params = choice.type_params()) {
         CARBON_RETURN_IF_ERROR(ResolveNames(**type_params, choice_scope));
@@ -893,7 +918,7 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
     }
     case DeclarationKind::AssociatedConstantDeclaration: {
       auto& let = cast<AssociatedConstantDeclaration>(declaration);
-      StaticScope constant_scope(&enclosing_scope);
+      StaticScope constant_scope(&enclosing_scope, &let);
       enclosing_scope.MarkDeclared(let.binding().name());
       CARBON_RETURN_IF_ERROR(ResolveNames(let.binding(), constant_scope));
       enclosing_scope.MarkUsable(let.binding().name());
@@ -924,19 +949,31 @@ auto NameResolver::ResolveNamesImpl(Declaration& declaration,
       break;
     }
   }
+
+  if (trace_stream_->is_enabled()) {
+    *trace_stream_ << "** finished resolving decl `";
+    declaration.PrintID(trace_stream_->stream());
+    *trace_stream_ << "` (" << declaration.source_loc() << ")\n";
+  }
+
   return Success();
 }
 
-auto ResolveNames(AST& ast) -> ErrorOr<Success> {
+auto ResolveNames(AST& ast, Nonnull<TraceStream*> trace_stream)
+    -> ErrorOr<Success> {
   return RunWithExtraStack([&]() -> ErrorOr<Success> {
-    NameResolver resolver;
+    NameResolver resolver(trace_stream);
+    SetFileContext set_file_ctx(*trace_stream, std::nullopt);
+    StaticScope file_scope(trace_stream);
 
-    StaticScope file_scope;
     for (auto* declaration : ast.declarations) {
+      set_file_ctx.update_source_loc(declaration->source_loc());
       CARBON_RETURN_IF_ERROR(resolver.AddExposedNames(
           *declaration, file_scope, /*allow_qualified_names=*/true));
     }
+
     for (auto* declaration : ast.declarations) {
+      set_file_ctx.update_source_loc(declaration->source_loc());
       CARBON_RETURN_IF_ERROR(resolver.ResolveNames(
           *declaration, file_scope,
           NameResolver::ResolveFunctionBodies::AfterDeclarations));
diff --git a/explorer/interpreter/resolve_names.h b/explorer/interpreter/resolve_names.h
index 01b5a5fa9e3b..7b8be2510db3 100644
--- a/explorer/interpreter/resolve_names.h
+++ b/explorer/interpreter/resolve_names.h
@@ -7,13 +7,15 @@
 
 #include "explorer/ast/ast.h"
 #include "explorer/common/arena.h"
+#include "explorer/common/trace_stream.h"
 
 namespace Carbon {
 
 // Resolves names (IdentifierExpressions) in the AST.
 // On failure, `ast` is left in a partial state and should not be further
 // processed.
-auto ResolveNames(AST& ast) -> ErrorOr<Success>;
+auto ResolveNames(AST& ast, Nonnull<TraceStream*> trace_stream)
+    -> ErrorOr<Success>;
 
 }  // namespace Carbon
 
diff --git a/explorer/trace_testdata/full_trace.carbon b/explorer/trace_testdata/full_trace.carbon
index 4a92abf4c1d1..7ac1f24a0a79 100644
--- a/explorer/trace_testdata/full_trace.carbon
+++ b/explorer/trace_testdata/full_trace.carbon
@@ -6,13 +6,68 @@
 // CHECK:STDOUT: ********** source program **********
 // CHECK:STDOUT: interface TestInterface {
 // CHECK:STDOUT: }
+// CHECK:STDOUT: namespace N;fn Foo (n: i32)-> i32 {
+// CHECK:STDOUT: {
+// CHECK:STDOUT: return (n + 1);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: }
 // CHECK:STDOUT: fn Main ()-> i32 {
 // CHECK:STDOUT: {
-// CHECK:STDOUT: return 0;
+// CHECK:STDOUT: return N.Foo(0);
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: }
 // CHECK:STDOUT: ********** resolving names **********
+
+
+package ExplorerTest api;
+
+// CHECK:STDOUT: --- declared `TestInterface` as `interface TestInterface` in `package` (full_trace.carbon:[[@LINE+1]])
+interface TestInterface {}
+
+// CHECK:STDOUT: --- declared `N` as `namespace N` in `package` (full_trace.carbon:[[@LINE+1]])
+namespace N;
+
+// CHECK:STDOUT: --- resolved `N` as `namespace N` in `package` (full_trace.carbon:[[@LINE+1]])
+fn N.Foo(n: i32) -> i32 {
+  return n + 1;
+// CHECK:STDOUT: --- declared `Foo` as `fn N.Foo` in `namespace N` (full_trace.carbon:[[@LINE+1]])
+}
+
+fn Main() -> i32 {
+  return N.Foo(0);
+// CHECK:STDOUT: --- declared `Main` as `fn Main` in `package` (full_trace.carbon:[[@LINE+440]])
+// CHECK:STDOUT: ** resolving decl `interface TestInterface` (full_trace.carbon:[[@LINE-14]])
+// CHECK:STDOUT: --- marked `TestInterface` declared but not usable in `package`
+// CHECK:STDOUT: --- marked `TestInterface` usable in `package`
+// CHECK:STDOUT: --- declared `Self` as `Self` in `interface TestInterface` (full_trace.carbon:[[@LINE-17]])
+// CHECK:STDOUT: ** finished resolving decl `interface TestInterface` (full_trace.carbon:[[@LINE-18]])
+// CHECK:STDOUT: ** resolving decl `namespace N` (full_trace.carbon:[[@LINE-16]])
+// CHECK:STDOUT: --- marked `N` usable in `package`
+// CHECK:STDOUT: ** finished resolving decl `namespace N` (full_trace.carbon:[[@LINE-18]])
+// CHECK:STDOUT: ** resolving decl `fn N.Foo` (full_trace.carbon:[[@LINE-13]])
+// CHECK:STDOUT: --- resolved `N` as `namespace N` in `package` (full_trace.carbon:[[@LINE-17]])
+// CHECK:STDOUT: --- marked `Foo` declared but not usable in `namespace N`
+// CHECK:STDOUT: --- declared `n` as `n` in `fn N.Foo` (full_trace.carbon:[[@LINE-19]])
+// CHECK:STDOUT: --- marked `Foo` usable in `namespace N`
+// CHECK:STDOUT: ** resolving stmt `{return (n + 1);}` (full_trace.carbon:[[@LINE-18]])
+// CHECK:STDOUT: ** resolving stmt `return (n + 1);` (full_trace.carbon:[[@LINE-21]])
+// CHECK:STDOUT: --- resolved `n` as `n` in `fn N.Foo` (full_trace.carbon:[[@LINE-22]])
+// CHECK:STDOUT: ** finished resolving stmt `return (n + 1);` (full_trace.carbon:[[@LINE-23]])
+// CHECK:STDOUT: ** finished resolving stmt `{return (n + 1);}` (full_trace.carbon:[[@LINE-22]])
+// CHECK:STDOUT: ** finished resolving decl `fn N.Foo` (full_trace.carbon:[[@LINE-23]])
+// CHECK:STDOUT: ** resolving decl `fn Main` (full_trace.carbon:[[@LINE+420]])
+// CHECK:STDOUT: --- marked `Main` declared but not usable in `package`
+// CHECK:STDOUT: --- marked `Main` usable in `package`
+// CHECK:STDOUT: ** resolving stmt `{return N.Foo(0);}` (full_trace.carbon:[[@LINE+417]])
+// CHECK:STDOUT: ** resolving stmt `return N.Foo(0);` (full_trace.carbon:[[@LINE-25]])
+// CHECK:STDOUT: --- resolved `N` as `namespace N` in `package` (full_trace.carbon:[[@LINE-26]])
+// CHECK:STDOUT: --- resolved `Foo` as `fn N.Foo` in `namespace N` (full_trace.carbon:[[@LINE-27]])
+// CHECK:STDOUT: ** finished resolving stmt `return N.Foo(0);` (full_trace.carbon:[[@LINE-28]])
+// CHECK:STDOUT: ** finished resolving stmt `{return N.Foo(0);}` (full_trace.carbon:[[@LINE+412]])
+// CHECK:STDOUT: ** finished resolving decl `fn Main` (full_trace.carbon:[[@LINE+411]])
+// CHECK:STDOUT: --- resolved `Main` as `fn Main` in `package` (<Main()>:0)
 // CHECK:STDOUT: ********** resolving control flow **********
 // CHECK:STDOUT: ********** type checking **********
 // CHECK:STDOUT: ** declaring interface TestInterface
@@ -22,6 +77,62 @@
 // CHECK:STDOUT: impl declarations:{{ }}
 // CHECK:STDOUT: impl declarations: bool as interface EqWith(U = bool), i32 as interface EqWith(U = i32), String as interface EqWith(U = String), i32 as interface CompareWith(U = i32), String as interface CompareWith(U = String), i32 as interface LessWith(U = i32), String as interface LessWith(U = String), i32 as interface LessEqWith(U = i32), String as interface LessEqWith(U = String), i32 as interface GreaterWith(U = i32), String as interface GreaterWith(U = String), i32 as interface GreaterEqWith(U = i32), String as interface GreaterEqWith(U = String), i32 as interface Negate, i32 as interface AddWith(U = i32), i32 as interface SubWith(U = i32), i32 as interface MulWith(U = i32), i32 as interface DivWith(U = i32), i32 as interface ModWith(U = i32), i32 as interface BitComplement, i32 as interface BitAndWith(U = i32), i32 as interface BitOrWith(U = i32), i32 as interface BitXorWith(U = i32), i32 as interface LeftShiftWith(U = i32), i32 as interface RightShiftWith(U = i32), i32 as interface Inc, i32 as interface Dec, U as interface __EqualConverter [0], (T1,) as interface As(T = (U1,)) [0, 0, 0; 1, 1, 0, 0, 0], (T1, T2) as interface As(T = (U1, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, U1) as interface EqWith(U = (T2, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, T2, T3) as interface As(T = (U1, U2, U3)) [0, 0, 0; 0, 0, 1; 0, 0, 2; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1; 1, 1, 0, 0, 2], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface AssignWith(U = U) [0; 1, 1, 0], T as interface AddAssignWith(U = U) [0; 1, 1, 0], T as interface SubAssignWith(U = U) [0; 1, 1, 0], T as interface MulAssignWith(U = U) [0; 1, 1, 0], T as interface DivAssignWith(U = U) [0; 1, 1, 0], T as interface ModAssignWith(U = U) [0; 1, 1, 0], T as interface BitAndAssignWith(U = U) [0; 1, 1, 0], T as interface BitOrAssignWith(U = U) [0; 1, 1, 0], T as interface BitXorAssignWith(U = U) [0; 1, 1, 0], T as interface LeftShiftAssignWith(U = U) [0; 1, 1, 0], T as interface RightShiftAssignWith(U = U) [0; 1, 1, 0]
 // CHECK:STDOUT: ** finished checking interface TestInterface
+// CHECK:STDOUT: checking NamespaceDeclaration
+// CHECK:STDOUT: ** declaring function Foo
+// CHECK:STDOUT: checking TuplePattern (n: i32)
+// CHECK:STDOUT: checking BindingPattern n: i32
+// CHECK:STDOUT: checking ExpressionPattern i32
+// CHECK:STDOUT: checking IntTypeLiteral i32
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: i32 .0. ## i32 .1.
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp i32 .0. (full_trace.carbon:[[@LINE-61]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: i32 .1. {{[[][[]}}i32]]
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: finished checking tuple pattern field n: i32
+// CHECK:STDOUT: checking IntTypeLiteral i32
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: i32 .0. ## i32 .1.
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp i32 .0. (full_trace.carbon:[[@LINE-80]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: i32 .1. {{[[][[]}}i32]]
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory:{{ }}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: ** finished declaring function Foo of type fn (i32,) -> i32
+// CHECK:STDOUT: checking FunctionDeclaration
+// CHECK:STDOUT: ** checking function Foo
+// CHECK:STDOUT: impl declarations:{{ }}
+// CHECK:STDOUT: impl declarations: bool as interface EqWith(U = bool), i32 as interface EqWith(U = i32), String as interface EqWith(U = String), i32 as interface CompareWith(U = i32), String as interface CompareWith(U = String), i32 as interface LessWith(U = i32), String as interface LessWith(U = String), i32 as interface LessEqWith(U = i32), String as interface LessEqWith(U = String), i32 as interface GreaterWith(U = i32), String as interface GreaterWith(U = String), i32 as interface GreaterEqWith(U = i32), String as interface GreaterEqWith(U = String), i32 as interface Negate, i32 as interface AddWith(U = i32), i32 as interface SubWith(U = i32), i32 as interface MulWith(U = i32), i32 as interface DivWith(U = i32), i32 as interface ModWith(U = i32), i32 as interface BitComplement, i32 as interface BitAndWith(U = i32), i32 as interface BitOrWith(U = i32), i32 as interface BitXorWith(U = i32), i32 as interface LeftShiftWith(U = i32), i32 as interface RightShiftWith(U = i32), i32 as interface Inc, i32 as interface Dec, U as interface __EqualConverter [0], (T1,) as interface As(T = (U1,)) [0, 0, 0; 1, 1, 0, 0, 0], (T1, T2) as interface As(T = (U1, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, U1) as interface EqWith(U = (T2, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, T2, T3) as interface As(T = (U1, U2, U3)) [0, 0, 0; 0, 0, 1; 0, 0, 2; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1; 1, 1, 0, 0, 2], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface AssignWith(U = U) [0; 1, 1, 0], T as interface AddAssignWith(U = U) [0; 1, 1, 0], T as interface SubAssignWith(U = U) [0; 1, 1, 0], T as interface MulAssignWith(U = U) [0; 1, 1, 0], T as interface DivAssignWith(U = U) [0; 1, 1, 0], T as interface ModAssignWith(U = U) [0; 1, 1, 0], T as interface BitAndAssignWith(U = U) [0; 1, 1, 0], T as interface BitOrAssignWith(U = U) [0; 1, 1, 0], T as interface BitXorAssignWith(U = U) [0; 1, 1, 0], T as interface LeftShiftAssignWith(U = U) [0; 1, 1, 0], T as interface RightShiftAssignWith(U = U) [0; 1, 1, 0]
+// CHECK:STDOUT: checking Block {
+// CHECK:STDOUT: return (n + 1);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: checking ReturnExpression return (n + 1);
+// CHECK:STDOUT: checking OperatorExpression (n + 1)
+// CHECK:STDOUT: checking IdentifierExpression n
+// CHECK:STDOUT: checking IntLiteral 1
+// CHECK:STDOUT: ** finished checking function Foo
 // CHECK:STDOUT: ** declaring function Main
 // CHECK:STDOUT: checking TuplePattern ()
 // CHECK:STDOUT: checking IntTypeLiteral i32
@@ -33,13 +144,7 @@
 // CHECK:STDOUT: stack: i32 .0. ## i32 .1.
 // CHECK:STDOUT: memory:{{ }}
 // CHECK:STDOUT: }
-
-
-package ExplorerTest api;
-
-interface TestInterface {}
-
-// CHECK:STDOUT: --- step exp i32 .0. (full_trace.carbon:[[@LINE+53]]) --->
+// CHECK:STDOUT: --- step exp i32 .0. (full_trace.carbon:[[@LINE-109]]) --->
 // CHECK:STDOUT: {
 // CHECK:STDOUT: stack: i32 .1. {{[[][[]}}i32]]
 // CHECK:STDOUT: memory:{{ }}
@@ -54,11 +159,20 @@ interface TestInterface {}
 // CHECK:STDOUT: impl declarations:{{ }}
 // CHECK:STDOUT: impl declarations: bool as interface EqWith(U = bool), i32 as interface EqWith(U = i32), String as interface EqWith(U = String), i32 as interface CompareWith(U = i32), String as interface CompareWith(U = String), i32 as interface LessWith(U = i32), String as interface LessWith(U = String), i32 as interface LessEqWith(U = i32), String as interface LessEqWith(U = String), i32 as interface GreaterWith(U = i32), String as interface GreaterWith(U = String), i32 as interface GreaterEqWith(U = i32), String as interface GreaterEqWith(U = String), i32 as interface Negate, i32 as interface AddWith(U = i32), i32 as interface SubWith(U = i32), i32 as interface MulWith(U = i32), i32 as interface DivWith(U = i32), i32 as interface ModWith(U = i32), i32 as interface BitComplement, i32 as interface BitAndWith(U = i32), i32 as interface BitOrWith(U = i32), i32 as interface BitXorWith(U = i32), i32 as interface LeftShiftWith(U = i32), i32 as interface RightShiftWith(U = i32), i32 as interface Inc, i32 as interface Dec, U as interface __EqualConverter [0], (T1,) as interface As(T = (U1,)) [0, 0, 0; 1, 1, 0, 0, 0], (T1, T2) as interface As(T = (U1, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, U1) as interface EqWith(U = (T2, U2)) [0, 0, 0; 0, 0, 1; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1], (T1, T2, T3) as interface As(T = (U1, U2, U3)) [0, 0, 0; 0, 0, 1; 0, 0, 2; 1, 1, 0, 0, 0; 1, 1, 0, 0, 1; 1, 1, 0, 0, 2], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface ImplicitAs(T = U) [0; 1, 1, 0], T as interface As(T = U) [0; 1, 1, 0], T as interface AssignWith(U = U) [0; 1, 1, 0], T as interface AddAssignWith(U = U) [0; 1, 1, 0], T as interface SubAssignWith(U = U) [0; 1, 1, 0], T as interface MulAssignWith(U = U) [0; 1, 1, 0], T as interface DivAssignWith(U = U) [0; 1, 1, 0], T as interface ModAssignWith(U = U) [0; 1, 1, 0], T as interface BitAndAssignWith(U = U) [0; 1, 1, 0], T as interface BitOrAssignWith(U = U) [0; 1, 1, 0], T as interface BitXorAssignWith(U = U) [0; 1, 1, 0], T as interface LeftShiftAssignWith(U = U) [0; 1, 1, 0], T as interface RightShiftAssignWith(U = U) [0; 1, 1, 0]
 // CHECK:STDOUT: checking Block {
-// CHECK:STDOUT: return 0;
+// CHECK:STDOUT: return N.Foo(0);
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: checking ReturnExpression return 0;
+// CHECK:STDOUT: checking ReturnExpression return N.Foo(0);
+// CHECK:STDOUT: checking CallExpression N.Foo(0)
+// CHECK:STDOUT: checking SimpleMemberAccessExpression N.Foo
+// CHECK:STDOUT: checking IdentifierExpression Foo
+// CHECK:STDOUT: checking TupleLiteral (0)
 // CHECK:STDOUT: checking IntLiteral 0
+// CHECK:STDOUT: checking call to function of type fn (i32,) -> i32
+// CHECK:STDOUT: with arguments of type: (i32,)
+// CHECK:STDOUT: performing argument deduction for bindings:{{ }}
+// CHECK:STDOUT: deducing i32 from i32
+// CHECK:STDOUT: deduction succeeded with results: {}
 // CHECK:STDOUT: ** finished checking function Main
 // CHECK:STDOUT: checking CallExpression Main()
 // CHECK:STDOUT: checking IdentifierExpression Main
@@ -71,9 +185,15 @@ interface TestInterface {}
 // CHECK:STDOUT: ********** printing declarations **********
 // CHECK:STDOUT: interface TestInterface {
 // CHECK:STDOUT: }
+// CHECK:STDOUT: namespace N;fn Foo (n: i32)-> i32 {
+// CHECK:STDOUT: {
+// CHECK:STDOUT: return (n + 1);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: }
 // CHECK:STDOUT: fn Main ()-> i32 {
 // CHECK:STDOUT: {
-// CHECK:STDOUT: return 0;
+// CHECK:STDOUT: return N.Foo(0);
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: }
@@ -83,7 +203,7 @@ interface TestInterface {}
 // CHECK:STDOUT: stack:{{ }}
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-// CHECK:STDOUT: --- step decl interface TestInterface .0. (full_trace.carbon:[[@LINE-46]]) --->
+// CHECK:STDOUT: --- step decl interface TestInterface .0. (full_trace.carbon:[[@LINE-179]]) --->
 // CHECK:STDOUT: {
 // CHECK:STDOUT: stack:{{ }}
 // CHECK:STDOUT: memory: 0: Heap{}
@@ -92,9 +212,25 @@ interface TestInterface {}
 // CHECK:STDOUT: stack:{{ }}
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-fn Main() -> i32 {
-  return 0;
-// CHECK:STDOUT: --- step decl fn Main .0. (full_trace.carbon:[[@LINE+106]]) --->
+// CHECK:STDOUT: --- step decl namespace N .0. (full_trace.carbon:[[@LINE-185]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step decl fn N.Foo .0. (full_trace.carbon:[[@LINE-188]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack:{{ }}
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step decl fn Main .0. (full_trace.carbon:[[@LINE+247]]) --->
 // CHECK:STDOUT: {
 // CHECK:STDOUT: stack:{{ }}
 // CHECK:STDOUT: memory: 0: Heap{}
@@ -141,63 +277,204 @@ fn Main() -> i32 {
 // CHECK:STDOUT: match pattern ()
 // CHECK:STDOUT: from value expression with value ()
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: {return 0;} .0. ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: {return N.Foo(0);} .0. ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-// CHECK:STDOUT: --- step stmt {return 0;} .0. (full_trace.carbon:[[@LINE+56]]) --->
+// CHECK:STDOUT: --- step stmt {return N.Foo(0);} .0. (full_trace.carbon:[[@LINE+197]]) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: return 0; .0. ## {return 0;} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: return N.Foo(0); .0. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-// CHECK:STDOUT: --- step stmt return 0; .0. (full_trace.carbon:[[@LINE-56]]) --->
+// CHECK:STDOUT: --- step stmt return N.Foo(0); .0. (full_trace.carbon:[[@LINE-249]]) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: 0 .0. ## return 0; .1. ## {return 0;} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: N.Foo(0) .0. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: 0 .0. ## 0 .1. ## return 0; .1. ## {return 0;} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: N.Foo(0) .0. ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-// CHECK:STDOUT: --- step exp 0 .0. (full_trace.carbon:[[@LINE-65]]) --->
+// CHECK:STDOUT: --- step exp N.Foo(0) .0. (full_trace.carbon:[[@LINE-258]]) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: 0 .1. {{[[][[]}}0]] ## return 0; .1. ## {return 0;} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: N.Foo .0. ## N.Foo(0) .1. ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: return 0; .1. {{[[][[]}}0]] ## {return 0;} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: stack: N.Foo .0. ## N.Foo .1. ## N.Foo(0) .1. ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
-// CHECK:STDOUT: --- step stmt return 0; .1. (full_trace.carbon:[[@LINE-74]]) --->
+// CHECK:STDOUT: --- step exp N.Foo .0. (full_trace.carbon:[[@LINE-267]]) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: clean up.0. {} ## clean up.0. {} ## Main() .3. {{[[][[]}}fun<Main>, (), 0]] {} ## Main() .1.
+// CHECK:STDOUT: stack: Foo .0. ## N.Foo .1. ## N.Foo(0) .1. ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp Foo .0. (full_trace.carbon:[[@LINE-272]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: N.Foo .1. {{[[][[]}}fun<N.Foo>]] ## N.Foo(0) .1. ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: clean up.0. {} ## Main() .3. {{[[][[]}}fun<Main>, (), 0]] {} ## Main() .1.
+// CHECK:STDOUT: stack: N.Foo(0) .1. {{[[][[]}}fun<N.Foo>]] ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp N.Foo(0) .1. (full_trace.carbon:[[@LINE-281]]) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: Main() .3. {{[[][[]}}fun<Main>, (), 0]] {} ## Main() .1.
+// CHECK:STDOUT: stack: (0) .0. ## N.Foo(0) .2. {{[[][[]}}fun<N.Foo>]] ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
 // CHECK:STDOUT: memory: 0: Heap{}
 // CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp (0) .0. (full_trace.carbon:[[@LINE-286]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: 0 .0. ## (0) .1. ## N.Foo(0) .2. {{[[][[]}}fun<N.Foo>]] ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp 0 .0. (full_trace.carbon:[[@LINE-291]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (0) .1. {{[[][[]}}0]] ## N.Foo(0) .2. {{[[][[]}}fun<N.Foo>]] ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp (0) .1. (full_trace.carbon:[[@LINE-296]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: N.Foo(0) .2. {{[[][[]}}fun<N.Foo>, (0,)]] ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp N.Foo(0) .2. (full_trace.carbon:[[@LINE-301]]) --->
+// CHECK:STDOUT: calling function: fun<N.Foo>
+// CHECK:STDOUT: match pattern (Placeholder<n>,)
+// CHECK:STDOUT: from value expression with value (0,)
+// CHECK:STDOUT: match pattern Placeholder<n>
+// CHECK:STDOUT: from value expression with value 0
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: {return (n + 1);} .0. ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step stmt {return (n + 1);} .0. (full_trace.carbon:[[@LINE-314]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: return (n + 1); .0. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step stmt return (n + 1); .0. (full_trace.carbon:[[@LINE-321]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (n + 1) .0. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (n + 1) .0. ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp (n + 1) .0. (full_trace.carbon:[[@LINE-330]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: n .0. ## (n + 1) .1. ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: n .0. ## n .1. ## (n + 1) .1. ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp n .0. (full_trace.carbon:[[@LINE-339]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: n .1. {{[[][[]}}0]] ## (n + 1) .1. ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (n + 1) .1. {{[[][[]}}0]] ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp (n + 1) .1. (full_trace.carbon:[[@LINE-348]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: 1 .0. ## (n + 1) .2. {{[[][[]}}0]] ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: 1 .0. ## 1 .1. ## (n + 1) .2. {{[[][[]}}0]] ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp 1 .0. (full_trace.carbon:[[@LINE-357]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: 1 .1. {{[[][[]}}1]] ## (n + 1) .2. {{[[][[]}}0]] ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (n + 1) .2. {{[[][[]}}0, 1]] ## (n + 1) .1. ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp (n + 1) .2. (full_trace.carbon:[[@LINE-366]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: (n + 1) .1. {{[[][[]}}1]] ## return (n + 1); .1. ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: return (n + 1); .1. {{[[][[]}}1]] ## {return (n + 1);} .1. {} ## .0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,)]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step stmt return (n + 1); .1. (full_trace.carbon:[[@LINE-375]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.0. {} ## clean up.0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.0. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: destroy.0. ## clean up.1. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.1. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: 0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.2. {n: i32: lval<Allocation(1)>} ## N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: N.Foo(0) .3. {{[[][[]}}fun<N.Foo>, (0,), 1]] {} ## N.Foo(0) .1. ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step exp N.Foo(0) .3. (full_trace.carbon:[[@LINE-395]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.0. {} ## N.Foo(0) .1. {{[[][[]}}1]] ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: N.Foo(0) .1. {{[[][[]}}1]] ## return N.Foo(0); .1. ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: return N.Foo(0); .1. {{[[][[]}}1]] ## {return N.Foo(0);} .1. {} ## .0. {} ## Main() .3. {{[[][[]}}fun<Main>, ()]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: --- step stmt return N.Foo(0); .1. (full_trace.carbon:[[@LINE-408]]) --->
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.0. {} ## clean up.0. {} ## Main() .3. {{[[][[]}}fun<Main>, (), 1]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: clean up.0. {} ## Main() .3. {{[[][[]}}fun<Main>, (), 1]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
+// CHECK:STDOUT: {
+// CHECK:STDOUT: stack: Main() .3. {{[[][[]}}fun<Main>, (), 1]] {} ## Main() .1.
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
+// CHECK:STDOUT: }
 // CHECK:STDOUT: --- step exp Main() .3. (<Main()>:0) --->
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: clean up.0. {} ## Main() .1. {{[[][[]}}0]]
-// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: stack: clean up.0. {} ## Main() .1. {{[[][[]}}1]]
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
 // CHECK:STDOUT: }
 // CHECK:STDOUT: {
-// CHECK:STDOUT: stack: Main() .1. {{[[][[]}}0]]
-// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: stack: Main() .1. {{[[][[]}}1]]
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
 // CHECK:STDOUT: }
 // CHECK:STDOUT: {
 // CHECK:STDOUT: stack:{{ }}
-// CHECK:STDOUT: memory: 0: Heap{}
+// CHECK:STDOUT: memory: 0: Heap{}, 1: !!0
 // CHECK:STDOUT: }
-// CHECK:STDOUT: interpreter result: 0
+// CHECK:STDOUT: interpreter result: 1
 // CHECK:STDOUT: ********** printing timing **********
 // CHECK:STDOUT: Time elapsed in ExecProgram: {{[0-9]+}}ms
 // CHECK:STDOUT: Time elapsed in AnalyzeProgram: {{[0-9]+}}ms
 // CHECK:STDOUT: Time elapsed in AddPrelude: {{[0-9]+}}ms
 // CHECK:STDOUT: Time elapsed in Parse: {{[0-9]+}}ms
-// CHECK:STDOUT: result: 0
+// CHECK:STDOUT: result: 1
 }