Pass the flag instead of using a global. (#893)

Arguably missed in #769 

Note, this is reminding me we have more class members to rename for `_`, but I felt it's best to use the new naming instead of adding more to clean up.

executable_semantics/interpreter/BUILD

@@ -98,7 +98,6 @@ cc_library(
         "//executable_semantics/ast:declaration",
         "//executable_semantics/ast:expression",
         "//executable_semantics/common:arena",
-        "//executable_semantics/common:tracing_flag",
         "@llvm-project//llvm:Support",
     ],
 )
@@ -121,7 +120,6 @@ cc_library(
         "//executable_semantics/ast:expression",
         "//executable_semantics/ast:statement",
         "//executable_semantics/common:arena",
-        "//executable_semantics/common:tracing_flag",
         "@llvm-project//llvm:Support",
     ],
 )

executable_semantics/interpreter/exec_program.cpp

@@ -7,7 +7,6 @@
 #include "common/check.h"
 #include "common/ostream.h"
 #include "executable_semantics/common/arena.h"
-#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/interpreter/interpreter.h"
 #include "executable_semantics/interpreter/type_checker.h"
 
@@ -34,23 +33,23 @@ static void AddIntrinsics(Nonnull<Arena*> arena,
   declarations->insert(declarations->begin(), print);
 }
 
-void ExecProgram(Nonnull<Arena*> arena, AST ast) {
+void ExecProgram(Nonnull<Arena*> arena, AST ast, bool trace) {
   AddIntrinsics(arena, &ast.declarations);
-  if (tracing_output) {
+  if (trace) {
     llvm::outs() << "********** source program **********\n";
     for (const auto decl : ast.declarations) {
       llvm::outs() << *decl;
     }
     llvm::outs() << "********** type checking **********\n";
   }
-  TypeChecker type_checker(arena);
+  TypeChecker type_checker(arena, trace);
   TypeChecker::TypeCheckContext p = type_checker.TopLevel(&ast.declarations);
   TypeEnv top = p.types;
   Env ct_top = p.values;
   for (const auto decl : ast.declarations) {
     type_checker.TypeCheck(decl, top, ct_top);
   }
-  if (tracing_output) {
+  if (trace) {
     llvm::outs() << "\n";
     llvm::outs() << "********** type checking complete **********\n";
     for (const auto decl : ast.declarations) {
@@ -63,7 +62,8 @@ void ExecProgram(Nonnull<Arena*> arena, AST ast) {
   Nonnull<Expression*> call_main = arena->New<CallExpression>(
       source_loc, arena->New<IdentifierExpression>(source_loc, "main"),
       arena->New<TupleLiteral>(source_loc));
-  int result = Interpreter(arena).InterpProgram(ast.declarations, call_main);
+  int result =
+      Interpreter(arena, trace).InterpProgram(ast.declarations, call_main);
   llvm::outs() << "result: " << result << "\n";
 }
 

executable_semantics/interpreter/exec_program.h

@@ -14,7 +14,7 @@
 namespace Carbon {
 
 // Runs the top-level declaration list.
-void ExecProgram(Nonnull<Arena*> arena, AST ast);
+void ExecProgram(Nonnull<Arena*> arena, AST ast, bool trace);
 
 }  // namespace Carbon
 

executable_semantics/interpreter/interpreter.cpp

@@ -16,7 +16,6 @@
 #include "executable_semantics/ast/expression.h"
 #include "executable_semantics/common/arena.h"
 #include "executable_semantics/common/error.h"
-#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/interpreter/action.h"
 #include "executable_semantics/interpreter/frame.h"
 #include "executable_semantics/interpreter/stack.h"
@@ -377,7 +376,7 @@ void Interpreter::PatternAssignment(Nonnull<const Value*> pat,
 auto Interpreter::StepLvalue() -> Transition {
   Nonnull<Action*> act = stack.Top()->todo.Top();
   const Expression& exp = cast<LValAction>(*act).expression();
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "--- step lvalue " << exp << " (" << exp.source_loc()
                  << ") --->\n";
   }
@@ -460,7 +459,7 @@ auto Interpreter::StepLvalue() -> Transition {
 auto Interpreter::StepExp() -> Transition {
   Nonnull<Action*> act = stack.Top()->todo.Top();
   const Expression& exp = cast<ExpressionAction>(*act).expression();
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "--- step exp " << exp << " (" << exp.source_loc()
                  << ") --->\n";
   }
@@ -658,7 +657,7 @@ auto Interpreter::StepExp() -> Transition {
 auto Interpreter::StepPattern() -> Transition {
   Nonnull<Action*> act = stack.Top()->todo.Top();
   const Pattern& pattern = cast<PatternAction>(*act).pattern();
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "--- step pattern " << pattern << " ("
                  << pattern.source_loc() << ") --->\n";
   }
@@ -741,7 +740,7 @@ auto Interpreter::StepStmt() -> Transition {
   Nonnull<Frame*> frame = stack.Top();
   Nonnull<Action*> act = frame->todo.Top();
   const Statement& stmt = cast<StatementAction>(*act).statement();
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "--- step stmt ";
     stmt.PrintDepth(1, llvm::outs());
     llvm::outs() << " (" << stmt.source_loc() << ") --->\n";
@@ -1136,7 +1135,7 @@ auto Interpreter::InterpProgram(llvm::ArrayRef<Nonnull<Declaration*>> fs,
   CHECK(stack.IsEmpty());
   CHECK(program_value == std::nullopt);
 
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "********** initializing globals **********\n";
   }
   InitGlobals(fs);
@@ -1145,14 +1144,14 @@ auto Interpreter::InterpProgram(llvm::ArrayRef<Nonnull<Declaration*>> fs,
   auto scopes = Stack<Nonnull<Scope*>>(arena->New<Scope>(globals));
   stack = Stack<Nonnull<Frame*>>(arena->New<Frame>("top", scopes, todo));
 
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "********** calling main function **********\n";
     PrintState(llvm::outs());
   }
 
   while (stack.Count() > 1 || !stack.Top()->todo.IsEmpty()) {
     Step();
-    if (tracing_output) {
+    if (trace_) {
       PrintState(llvm::outs());
     }
   }

executable_semantics/interpreter/interpreter.h

@@ -25,8 +25,8 @@ using Env = Dictionary<std::string, Address>;
 
 class Interpreter {
  public:
-  explicit Interpreter(Nonnull<Arena*> arena)
-      : arena(arena), globals(arena), heap(arena) {}
+  explicit Interpreter(Nonnull<Arena*> arena, bool trace)
+      : arena(arena), globals(arena), heap(arena), trace_(trace) {}
 
   // Interpret the whole program.
   auto InterpProgram(llvm::ArrayRef<Nonnull<Declaration*>> fs,
@@ -160,6 +160,8 @@ class Interpreter {
   Stack<Nonnull<Frame*>> stack;
   Heap heap;
   std::optional<Nonnull<const Value*>> program_value;
+
+  bool trace_;
 };
 
 }  // namespace Carbon

executable_semantics/interpreter/type_checker.cpp

@@ -14,7 +14,6 @@
 #include "executable_semantics/ast/declaration.h"
 #include "executable_semantics/common/arena.h"
 #include "executable_semantics/common/error.h"
-#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/interpreter/interpreter.h"
 #include "executable_semantics/interpreter/value.h"
 #include "llvm/ADT/StringExtras.h"
@@ -418,7 +417,7 @@ auto TypeChecker::Substitute(TypeEnv dict, Nonnull<const Value*> type)
 
 auto TypeChecker::TypeCheckExp(Nonnull<Expression*> e, TypeEnv types,
                                Env values) -> TCResult {
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "checking expression " << *e << "\ntypes: ";
     PrintTypeEnv(types, llvm::outs());
     llvm::outs() << "\nvalues: ";
@@ -708,7 +707,7 @@ auto TypeChecker::TypeCheckExp(Nonnull<Expression*> e, TypeEnv types,
 auto TypeChecker::TypeCheckPattern(
     Nonnull<Pattern*> p, TypeEnv types, Env values,
     std::optional<Nonnull<const Value*>> expected) -> TCResult {
-  if (tracing_output) {
+  if (trace_) {
     llvm::outs() << "checking pattern " << *p;
     if (expected) {
       llvm::outs() << ", expecting " << **expected;

executable_semantics/interpreter/type_checker.h

@@ -20,8 +20,8 @@ using TypeEnv = Dictionary<std::string, Nonnull<const Value*>>;
 
 class TypeChecker {
  public:
-  explicit TypeChecker(Nonnull<Arena*> arena)
-      : arena(arena), interpreter(arena) {}
+  explicit TypeChecker(Nonnull<Arena*> arena, bool trace)
+      : arena(arena), interpreter(arena, trace), trace_(trace) {}
 
   struct TypeCheckContext {
     explicit TypeCheckContext(Nonnull<Arena*> arena)
@@ -139,6 +139,8 @@ class TypeChecker {
 
   Nonnull<Arena*> arena;
   Interpreter interpreter;
+
+  bool trace_;
 };
 
 }  // namespace Carbon