util: Improving --trace-deprecation

This patch allows `util.deprecate` to print the deprecate messages
multiple times, if the call is made from different lines of source
code.

lib/util.js

@@ -62,17 +62,26 @@ exports.deprecate = function(fn, msg) {
   }
 
   var warned = false;
+  const warnedLines = new Set();
+
   function deprecated() {
+    var location = (new Error()).stack.match(/.*?\n.*\n.*?\((.*?:\d+):/)[1];
+
     if (!warned) {
       if (process.throwDeprecation) {
         throw new Error(msg);
       } else if (process.traceDeprecation) {
-        console.trace(msg);
+        if (!warnedLines.has(location)) {
+          warnedLines.add(location);
+          console.trace(msg);
+        }
+        warned = true;
       } else {
         console.error(msg);
       }
-      warned = true;
+      warned = !warned;
     }
+
     return fn.apply(this, arguments);
   }
 
@@ -766,38 +775,38 @@ exports.p = exports.deprecate(function() {
   for (var i = 0, len = arguments.length; i < len; ++i) {
     console.error(exports.inspect(arguments[i]));
   }
-}, 'util.p: Use console.error() instead');
+}, '[node] util.p is deprecated. Use console.error instead');
 
 
 exports.exec = exports.deprecate(function() {
   return require('child_process').exec.apply(this, arguments);
-}, 'util.exec is now called `child_process.exec`.');
+}, '[node] util.exec is deprecated. Use child_process.exec instead');
 
 
 exports.print = exports.deprecate(function() {
   for (var i = 0, len = arguments.length; i < len; ++i) {
     process.stdout.write(String(arguments[i]));
   }
-}, 'util.print: Use console.log instead');
+}, '[node] util.print is deprecated. Use console.log instead');
 
 
 exports.puts = exports.deprecate(function() {
   for (var i = 0, len = arguments.length; i < len; ++i) {
     process.stdout.write(arguments[i] + '\n');
   }
-}, 'util.puts: Use console.log instead');
+}, '[node] util.puts is deprecated. Use console.log instead');
 
 
 exports.debug = exports.deprecate(function(x) {
   process.stderr.write('DEBUG: ' + x + '\n');
-}, 'util.debug: Use console.error instead');
+}, '[node] util.debug is deprecated. Use console.error instead');
 
 
 exports.error = exports.deprecate(function(x) {
   for (var i = 0, len = arguments.length; i < len; ++i) {
     process.stderr.write(arguments[i] + '\n');
   }
-}, 'util.error: Use console.error instead');
+}, '[node] util.error is deprecated. Use console.error instead');
 
 
 exports.pump = exports.deprecate(function(readStream, writeStream, callback) {
@@ -835,7 +844,7 @@ exports.pump = exports.deprecate(function(readStream, writeStream, callback) {
     readStream.destroy();
     call(err);
   });
-}, 'util.pump(): Use readableStream.pipe() instead');
+}, '[node] util.pump is deprecated. Use readableStream.pipe instead');
 
 
 exports._errnoException = function(err, syscall, original) {

test/fixtures/deprecated-multiple-times-same-line.js

@@ -0,0 +1 @@
+require('util').p('This is deprecated'); require('util').p('This is deprecated');

test/fixtures/deprecated-multiple-times.js

@@ -0,0 +1,3 @@
+require('util').p('This is deprecated');
+require('util').p('This is deprecated');
+require('util').p('This is deprecated');

test/sequential/test-deprecation-flags.js

@@ -8,13 +8,20 @@ var node = process.execPath;
 var normal = [depmod];
 var noDep = ['--no-deprecation', depmod];
 var traceDep = ['--trace-deprecation', depmod];
+var traceDepMultiple = ['--trace-deprecation',
+    require.resolve('../fixtures/deprecated-multiple-times.js')];
+var traceDepMultipleSameLine = ['--trace-deprecation',
+    require.resolve('../fixtures/deprecated-multiple-times-same-line.js')];
+var traceMessage =
+        'Trace: [node] util.p is deprecated. Use console.error instead';
 
 execFile(node, normal, function(er, stdout, stderr) {
   console.error('normal: show deprecation warning');
   assert.equal(er, null);
   assert.equal(stdout, '');
   assert.equal(stderr,
-               'util.p: Use console.error() instead\n\'This is deprecated\'\n');
+               '[node] util.p is deprecated. ' +
+               'Use console.error instead\n\'This is deprecated\'\n');
   console.log('normal ok');
 });
 
@@ -32,7 +39,37 @@ execFile(node, traceDep, function(er, stdout, stderr) {
   assert.equal(stdout, '');
   var stack = stderr.trim().split('\n');
   // just check the top and bottom.
-  assert.equal(stack[0], 'Trace: util.p: Use console.error() instead');
+  assert.equal(stack[0], traceMessage);
   assert.equal(stack.pop(), '\'This is deprecated\'');
   console.log('trace ok');
 });
+
+execFile(node, traceDepMultiple, function(er, stdout, stderr) {
+  console.error('--trace-deprecation: deprecation message printed 3 times');
+  assert.equal(er, null);
+  assert.equal(stdout, '');
+
+  var count = stderr.trim().split('\n').filter(function(currentLine) {
+    return currentLine === traceMessage;
+  }).length;
+
+  // because we invoked the same function three times
+  assert.equal(count, 3);
+
+  console.log('trace ok');
+});
+
+execFile(node, traceDepMultipleSameLine, function(er, stdout, stderr) {
+  console.error('--trace-deprecation: deprecation message printed only once');
+  assert.equal(er, null);
+  assert.equal(stdout, '');
+
+  var count = stderr.trim().split('\n').filter(function(currentLine) {
+    return currentLine === traceMessage;
+  }).length;
+
+  // because we invoked the same function two times, but in the same line
+  assert.equal(count, 1);
+
+  console.log('trace ok');
+});