Add new options to inputs tool.

Add new options to the `inputs` tool in order to change
the format of its output:

- `--no-shell-escape` to avoid shell-escaping the results.

- `--dependency-order` to return results in dependency order,
  instead of sorting them alphabetically.

- `--print0` to use \0 as the list separator in the list,
  useful to process the target paths with `xargs -0` and
  similar tools.

misc/output_test.py

@@ -213,8 +213,17 @@ def test_tool_inputs(self) -> None:
 out2
 ''')
 
-        # Verify that results are shell-escaped by default.
-        # Also verify that phony outputs are never part of the results.
+        self.assertEqual(run(plan, flags='-t inputs --dependency-order out3'),
+'''in2
+in1
+out1
+out2
+implicit
+order_only
+''')
+
+        # Verify that results are shell-escaped by default, unless --no-shell-escape
+        # is used. Also verify that phony outputs are never part of the results.
         quote = '"' if platform.system() == "Windows" else "'"
 
         plan = '''
@@ -226,12 +235,47 @@ def test_tool_inputs(self) -> None:
 build all: phony out$ 3
 '''
 
+        # Quoting changes the order of results when sorting alphabetically.
         self.assertEqual(run(plan, flags='-t inputs all'),
 f'''{quote}out 2{quote}
 in1
 out1
 ''')
 
+        self.assertEqual(run(plan, flags='-t inputs --no-shell-escape all'),
+'''in1
+out 2
+out1
+''')
+
+        # But not when doing dependency order.
+        self.assertEqual(
+            run(
+              plan,
+              flags='-t inputs --dependency-order all'
+            ),
+            f'''in1
+out1
+{quote}out 2{quote}
+''')
+
+        self.assertEqual(
+          run(
+            plan,
+            flags='-t inputs --dependency-order --no-shell-escape all'
+          ),
+          f'''in1
+out1
+out 2
+''')
+
+        self.assertEqual(
+          run(
+            plan,
+            flags='-t inputs --dependency-order --no-shell-escape --print0 all'
+          ),
+          f'''in1\0out1\0out 2\0'''
+        )
 
 
     def test_explain_output(self):

src/ninja.cc

@@ -767,23 +767,44 @@ int NinjaMain::ToolInputs(const Options* options, int argc, char* argv[]) {
   argc++;
   argv--;
 
+  bool print0 = false;
+  bool shell_escape = true;
+  bool dependency_order = false;
+
   optind = 1;
   int opt;
   const option kLongOptions[] = { { "help", no_argument, NULL, 'h' },
+                                  { "no-shell-escape", no_argument, NULL, 'E' },
+                                  { "print0", no_argument, NULL, '0' },
+                                  { "dependency-order", no_argument, NULL,
+                                    'd' },
                                   { NULL, 0, NULL, 0 } };
-  while ((opt = getopt_long(argc, argv, "h", kLongOptions, NULL)) != -1) {
+  while ((opt = getopt_long(argc, argv, "h0Ed", kLongOptions, NULL)) != -1) {
     switch (opt) {
+    case 'd':
+      dependency_order = true;
+      break;
+    case 'E':
+      shell_escape = false;
+      break;
+    case '0':
+      print0 = true;
+      break;
     case 'h':
     default:
       // clang-format off
       printf(
 "Usage '-t inputs [options] [targets]\n"
 "\n"
-"List all inputs used for a set of targets.\n"
-"Note that results are shell escaped, and sorted alphabetically,\n"
+"List all inputs used for a set of targets, sorted in dependency order.\n"
+"Note that by default, results are shell escaped, and sorted alphabetically,\n"
 "and never include validation target paths.\n\n"
 "Options:\n"
-"  -h, --help   Print this message.\n");
+"  -h, --help          Print this message.\n"
+"  -0, --print0            Use \\0, instead of \\n as a line terminator.\n"
+"  -E, --no-shell-escape   Do not shell escape the result.\n"
+"  -d, --dependency-order  Sort results by dependency order.\n"
+      );
       // clang-format on
       return 1;
     }
@@ -802,12 +823,20 @@ int NinjaMain::ToolInputs(const Options* options, int argc, char* argv[]) {
   for (const Node* node : nodes)
     collector.VisitNode(node);
 
-  std::vector<std::string> inputs = collector.GetInputsAsStrings(true);
-  std::sort(inputs.begin(), inputs.end());
-
-  for (const std::string& input : inputs)
-    puts(input.c_str());
+  std::vector<std::string> inputs = collector.GetInputsAsStrings(shell_escape);
+  if (!dependency_order)
+    std::sort(inputs.begin(), inputs.end());
 
+  if (print0) {
+    for (const std::string& input : inputs) {
+      fwrite(input.c_str(), input.size(), 1, stdout);
+      fputc('\0', stdout);
+    }
+    fflush(stdout);
+  } else {
+    for (const std::string& input : inputs)
+      puts(input.c_str());
+  }
   return 0;
 }