From 29dd267a6dd009c56b356f5a8ded744df9e0daca Mon Sep 17 00:00:00 2001
From: Jinank Jain <ug201210017@iitj.ac.in>
Date: Wed, 6 May 2015 15:33:28 +0200
Subject: [PATCH] Fixed #5933

---
 README.md                      |  9 ++++++---
 python/servo/build_commands.py | 18 +++++++++++++++++-
 python/servo/command_base.py   |  2 +-
 servobuild.example             |  3 +++
 4 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 126973503694..b395e17f6d56 100644
--- a/README.md
+++ b/README.md
@@ -74,15 +74,18 @@ Mach tools to orchestrate the build and other tasks.
 
 ### Normal build
 
+
+To build Servo in development mode.  This is useful for development, but
+the resulting binary is very slow.
+
 ``` sh
 git clone https://github.com/servo/servo
 cd servo
-./mach build
+./mach build --dev
 ./mach run tests/html/about-mozilla.html
 ```
 
-By default, Servo builds in debug mode.  This is useful for development, but
-the resulting binary is very slow.  For benchmarking, performance testing, or
+For benchmarking, performance testing, or
 real-world use, add the `--release` flag to create an optimized build:
 
 ``` sh
diff --git a/python/servo/build_commands.py b/python/servo/build_commands.py
index ca9075a48f00..13bde25fbe6a 100644
--- a/python/servo/build_commands.py
+++ b/python/servo/build_commands.py
@@ -70,6 +70,9 @@ class MachCommands(CommandBase):
     @CommandArgument('--release', '-r',
                      action='store_true',
                      help='Build in release mode')
+    @CommandArgument('--dev', '-d',
+                     action='store_true',
+                     help='Build in development mode')
     @CommandArgument('--jobs', '-j',
                      default=None,
                      help='Number of jobs to run in parallel')
@@ -86,7 +89,7 @@ class MachCommands(CommandBase):
                      help='Print verbose output')
     @CommandArgument('params', nargs='...',
                      help="Command-line arguments to be passed through to Cargo")
-    def build(self, target=None, release=False, jobs=None, android=None,
+    def build(self, target=None, release=False, jobs=None, android=None, dev=False,
               verbose=False, debug_mozjs=False, params=None):
         self.ensure_bootstrapped()
 
@@ -96,6 +99,19 @@ def build(self, target=None, release=False, jobs=None, android=None,
         opts = params or []
         features = []
 
+        if not(release or dev):
+            if self.config["build"]["mode"] == "dev":
+                dev = True
+            elif self.config["build"]["mode"] == "release":
+                release = True 
+            else:
+                print("Please specify either --dev(or -d) for a development build or --release(or -r) for an optimized build.")
+                sys.exit(1)
+
+        if release and dev:
+            print("Please specify either --dev(or -d) for a development build or --release(or -r) for an optimized build.")
+            sys.exit(1)
+
         if release:
             opts += ["--release"]
         if target:
diff --git a/python/servo/command_base.py b/python/servo/command_base.py
index 8047bf441796..a46fd21dfc1c 100644
--- a/python/servo/command_base.py
+++ b/python/servo/command_base.py
@@ -93,7 +93,7 @@ def resolverelative(category, key):
 
         self.config.setdefault("build", {})
         self.config["build"].setdefault("android", False)
-
+        self.config["build"].setdefault("mode", "")
         self.config["build"].setdefault("debug-mozjs", False)
 
         self.config.setdefault("android", {})
diff --git a/servobuild.example b/servobuild.example
index 1396c73126e0..a29ec9aaf27f 100644
--- a/servobuild.example
+++ b/servobuild.example
@@ -23,6 +23,9 @@ system-cargo = false
 cargo-root = "/path/to/cargo"
 
 [build]
+# Set "mode = dev" or use `mach build --dev` to build the project with warning.
+# or Set "mode = release" or use `mach build --release` for optimized build.
+mode = "dev"
 # Set "android = true" or use `mach build --android` to build the Android app.
 android = false
 # Set "debug-mozjs" or use `mach build --debug-mozjs` to build a debug spidermonkey.