Move tracing_flag into a common directory (#669)

Intended to combine well with #668, so neither is alone.

executable_semantics/BUILD

@@ -12,18 +12,12 @@ cc_binary(
     name = "executable_semantics",
     srcs = ["main.cpp"],
     deps = [
+        "//executable_semantics/common:tracing_flag",
         "//executable_semantics/syntax",
         "@llvm-project//llvm:Support",
     ],
 )
 
-cc_library(
-    name = "tracing_flag",
-    srcs = ["tracing_flag.cpp"],
-    hdrs = ["tracing_flag.h"],
-    visibility = ["//executable_semantics:__subpackages__"],
-)
-
 EXAMPLES = [
     "assignment_copy1",
     "assignment_copy2",

executable_semantics/common/BUILD

@@ -0,0 +1,12 @@
+# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+# Exceptions. See /LICENSE for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+package(default_visibility = ["//executable_semantics:__subpackages__"])
+
+cc_library(
+    name = "tracing_flag",
+    srcs = ["tracing_flag.cpp"],
+    hdrs = ["tracing_flag.h"],
+    visibility = ["//executable_semantics:__subpackages__"],
+)

executable_semantics/common/tracing_flag.cpp

@@ -2,11 +2,10 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "executable_semantics/tracing_flag.h"
+#include "executable_semantics/common/tracing_flag.h"
 
 namespace Carbon {
 
-// Program option to enable/disable tracing.
 bool tracing_output = false;
 
 }  // namespace Carbon

executable_semantics/common/tracing_flag.h

@@ -2,8 +2,8 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifndef EXECUTABLE_SEMANTICS_TRACING_FLAG_H_
-#define EXECUTABLE_SEMANTICS_TRACING_FLAG_H_
+#ifndef EXECUTABLE_SEMANTICS_COMMON_TRACING_FLAG_H_
+#define EXECUTABLE_SEMANTICS_COMMON_TRACING_FLAG_H_
 
 namespace Carbon {
 
@@ -12,4 +12,4 @@ extern bool tracing_output;
 
 }  // namespace Carbon
 
-#endif  // EXECUTABLE_SEMANTICS_TRACING_FLAG_H_
+#endif  // EXECUTABLE_SEMANTICS_COMMON_TRACING_FLAG_H_

executable_semantics/interpreter/BUILD

@@ -87,10 +87,10 @@ cc_library(
         ":value",
         "//common:check",
         "//common:ostream",
-        "//executable_semantics:tracing_flag",
         "//executable_semantics/ast:declaration",
         "//executable_semantics/ast:expression",
         "//executable_semantics/ast:function_definition",
+        "//executable_semantics/common:tracing_flag",
     ],
 )
 
@@ -102,10 +102,10 @@ cc_library(
         ":containers",
         ":interpreter",
         "//common:ostream",
-        "//executable_semantics:tracing_flag",
         "//executable_semantics/ast:expression",
         "//executable_semantics/ast:function_definition",
         "//executable_semantics/ast:statement",
+        "//executable_semantics/common:tracing_flag",
     ],
 )
 

executable_semantics/interpreter/interpreter.cpp

@@ -14,10 +14,10 @@
 #include "common/check.h"
 #include "executable_semantics/ast/expression.h"
 #include "executable_semantics/ast/function_definition.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"
-#include "executable_semantics/tracing_flag.h"
 
 namespace Carbon {
 

executable_semantics/interpreter/typecheck.cpp

@@ -11,8 +11,8 @@
 #include <vector>
 
 #include "executable_semantics/ast/function_definition.h"
+#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/interpreter/interpreter.h"
-#include "executable_semantics/tracing_flag.h"
 
 namespace Carbon {
 

executable_semantics/main.cpp

@@ -6,9 +6,9 @@
 #include <cstring>
 #include <iostream>
 
+#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/syntax/parse.h"
 #include "executable_semantics/syntax/syntax_helpers.h"
-#include "executable_semantics/tracing_flag.h"
 #include "llvm/Support/CommandLine.h"
 
 int main(int argc, char* argv[]) {

executable_semantics/syntax/BUILD

@@ -30,9 +30,9 @@ cc_library(
     deps = [
         ":paren_contents",
         "//common:ostream",
-        "//executable_semantics:tracing_flag",
         "//executable_semantics/ast:declaration",
         "//executable_semantics/ast:expression",
+        "//executable_semantics/common:tracing_flag",
         "//executable_semantics/interpreter",
         "//executable_semantics/interpreter:typecheck",
     ],

executable_semantics/syntax/lexer.lpp

@@ -8,7 +8,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #include <cstdlib>
 #include <iostream>
 
-#include "executable_semantics/tracing_flag.h"
+#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/syntax/parse_and_lex_context.h"
 #include "llvm/ADT/StringExtras.h"
 %}

executable_semantics/syntax/parse.cpp

@@ -6,9 +6,9 @@
 
 #include <iostream>
 
+#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/syntax/parse_and_lex_context.h"
 #include "executable_semantics/syntax/parser.h"
-#include "executable_semantics/tracing_flag.h"
 
 extern FILE* yyin;
 

executable_semantics/syntax/syntax_helpers.cpp

@@ -5,9 +5,9 @@
 #include "executable_semantics/syntax/syntax_helpers.h"
 
 #include "common/ostream.h"
+#include "executable_semantics/common/tracing_flag.h"
 #include "executable_semantics/interpreter/interpreter.h"
 #include "executable_semantics/interpreter/typecheck.h"
-#include "executable_semantics/tracing_flag.h"
 
 namespace Carbon {