From e273ecce4ca3f90d75a7b185de5e03af97da5d96 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Sun, 5 Feb 2017 14:45:00 +0100
Subject: [PATCH] Option configuration to enable incremental compilation.

https://internals.rust-lang.org/t/incremental-compilation-beta/4721
---
 python/servo/command_base.py | 3 +++
 servobuild.example           | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/python/servo/command_base.py b/python/servo/command_base.py
index e80c9cb018b..8149a705014 100644
--- a/python/servo/command_base.py
+++ b/python/servo/command_base.py
@@ -270,6 +270,7 @@ class CommandBase(object):
         self.config["build"].setdefault("debug-mozjs", False)
         self.config["build"].setdefault("ccache", "")
         self.config["build"].setdefault("rustflags", "")
+        self.config["build"].setdefault("incremental", False)
 
         self.config.setdefault("android", {})
         self.config["android"].setdefault("sdk", "")
@@ -427,6 +428,8 @@ class CommandBase(object):
             env["PATH"] = "%s%s%s" % (os.pathsep.join(extra_path), os.pathsep, env["PATH"])
 
         env["CARGO_HOME"] = self.config["tools"]["cargo-home-dir"]
+        if self.config["build"]["incremental"]:
+            env["CARGO_INCREMENTAL"] = "1"
 
         if extra_lib:
             if sys.platform == "darwin":
diff --git a/servobuild.example b/servobuild.example
index a037c80a863..1cf444f57aa 100644
--- a/servobuild.example
+++ b/servobuild.example
@@ -38,15 +38,22 @@ rustc-with-gold = true
 # or Set "mode = release" or use `mach build --release` for optimized build.
 # Defaults to prompting before building
 #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.
 debug-mozjs = false
+
 # Set to the path to your ccache binary to enable caching of compiler outputs
 #ccache = "/usr/local/bin/ccache"
+
 # Any optional flags that will be added to $RUSTFLAGS
 #rustflags = ""
 
+# Enable rustc’s incremental compilation
+#incremental = false
+
 # Android information
 [android]
 # Defaults to the value of $ANDROID_SDK, $ANDROID_NDK, $ANDROID_TOOLCHAIN, $ANDROID_PLATFORM respectively