Auto merge of #13620 - Manishearth:type-assert, r=emilio

Test that Servo_* functions have the right signatures

Fixes #12992

Needs #13617

Not very happy with this solution (and perhaps it should be done in pure Rust, though that can be split out as another easy bug).

But it works. The bindings changes are from running a regen on [bug 1308234](https://bugzilla.mozilla.org/show_bug.cgi?id=1308234)

r? @emilio

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tests/unit/stylo/Cargo.toml

@@ -4,6 +4,8 @@ version = "0.0.1"
 authors = ["The Servo Project Developers"]
 license = "MPL-2.0"
 
+build = "build.rs"
+
 [lib]
 name = "stylo_tests"
 path = "lib.rs"
@@ -11,6 +13,15 @@ doctest = false
 
 [dependencies]
 app_units = "0.3"
-cssparser = {version = "0.7", features = ["heap_size"]}
-style = {path = "../../../components/style", features = ["gecko"]}
+env_logger = "0.3"
+euclid = "0.10.1"
+lazy_static = "0.2"
+libc = "0.2"
+log = {version = "0.3.5", features = ["release_max_level_info"]}
+num_cpus = "0.2.2"
+parking_lot = "0.3"
+selectors = "0.13"
+url = "1.2"
 style_traits = {path = "../../../components/style_traits"}
+geckoservo = {path = "../../../ports/geckolib"}
+style = {path = "../../../components/style", features = ["gecko"]}

tests/unit/stylo/build.rs

@@ -0,0 +1,13 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::process::Command;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=check_bindings.py");
+    println!("cargo:rerun-if-changed=../../../ports/geckolib/glue.rs");
+    assert!(Command::new("python").arg("./check_bindings.py")
+                                  .spawn().unwrap().wait().unwrap().success());
+}

tests/unit/stylo/check_bindings.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import re
+
+ROOT_PATH = os.path.join("..", "..", "..")
+INPUT_FILE = os.path.join(ROOT_PATH, "components", "style", "gecko_bindings", "bindings.rs")
+OUTPUT_FILE = os.path.join(os.environ["OUT_DIR"], "check_bindings.rs")
+GLUE_FILE = os.path.join(ROOT_PATH, "ports", "geckolib", "glue.rs")
+GLUE_OUTPUT_FILE = os.path.join(os.environ["OUT_DIR"], "glue.rs")
+
+TEMPLATE = """\
+    [ Servo_{name}, bindings::Servo_{name} ];
+"""
+
+with open(INPUT_FILE, "r") as bindings, open(OUTPUT_FILE, "w+") as tests:
+    tests.write("fn assert_types() {\n")
+
+    pattern = re.compile("fn\s*Servo_([a-zA-Z0-9_]+)\s*\(")
+
+    for line in bindings:
+        match = pattern.search(line)
+
+        # GetStyleVariables is a Servo_* function, but temporarily defined on
+        # the gecko side
+        if match and match.group(1) != "GetStyleVariables":
+            tests.write(TEMPLATE.format(name=match.group(1)))
+
+    tests.write("}\n")
+
+with open(GLUE_FILE, "r") as glue, open(GLUE_OUTPUT_FILE, "w+") as glue_output:
+    for line in glue:
+        glue_output.write(line.replace("pub extern \"C\" fn", "pub unsafe extern \"C\" fn"))

tests/unit/stylo/lib.rs

@@ -3,8 +3,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 extern crate app_units;
-extern crate cssparser;
+extern crate env_logger;
+extern crate euclid;
+extern crate geckoservo;
+extern crate libc;
+#[macro_use] extern crate log;
+extern crate parking_lot;
 extern crate style;
-extern crate style_traits;
+extern crate url;
 
 mod sanity_checks;
+
+mod servo_function_signatures;
+

tests/unit/stylo/servo_function_signatures.rs

@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#![allow(unused)]
+
+use self::glue::*;
+use style::gecko_bindings::bindings;
+use style::gecko_properties::*;
+
+include!(concat!(env!("OUT_DIR"), "/check_bindings.rs"));
+
+#[allow(non_snake_case, unused_unsafe, private_no_mangle_fns)]
+mod glue {
+    // this module pretends to be glue.rs, with the safe functions swapped for unsafe ones. This is
+    // a hack to compensate for the fact that `fn` types cannot coerce to `unsafe fn` types. The
+    // imports are populated with the same things so the type assertion should be equivalent
+    use geckoservo::*;
+    include!(concat!(env!("OUT_DIR"), "/glue.rs"));
+}