Auto merge of #24005 - ferjm:windows.pkgconfig, r=Manishearth

Simplify Windows build by not setting PKG_CONFIG_PATH

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #23177

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README.md

@@ -215,7 +215,7 @@ You should change the installation to install the "Add python.exe to Path" featu
 
 2. Install Python 3.7 for Windows (https://www.python.org/downloads/release/python-374/). The Windows x86-64 MSI installer is fine. This is required in order to build the JavaScript engine, SpiderMonkey.
 
-2. Install virtualenv.
+3. Install virtualenv.
 
  In a normal Windows Shell (cmd.exe or "Command Prompt" from the start menu), do:
  ```
@@ -223,14 +223,21 @@ pip install virtualenv
 ```
  If this does not work, you may need to reboot for the changed PATH settings (by the python installer) to take effect.
 
-3. Install the most recent [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) MSVC development package following [these instructions](https://github.com/sdroege/gstreamer-rs#gstreamer-binaries-1). Note that the MinGW binaries will not work, so make sure that you install the MSVC the ones.
+4. Install `pkg-config` either via [Chocolatey](https://chocolatey.org/install#installing-chocolatey)(`choco install pkgconfiglite`) or from [here](https://sourceforge.net/projects/pkgconfiglite/).
+
+5. Install the most recent [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) MSVC packages. You need to download the two `.msi` files for your platform from the [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) website and install them. The currently recommended version is 1.16.0. i.e.:
+
+- [gstreamer-1.0-msvc-x86_64-1.16.0.msi](https://gstreamer.freedesktop.org/data/pkg/windows/1.16.0/gstreamer-1.0-msvc-x86_64-1.16.0.msi)
+- [gstreamer-1.0-devel-msvc-x86_64-1.16.0.msi](https://gstreamer.freedesktop.org/data/pkg/windows/1.16.0/gstreamer-1.0-devel-msvc-x86_64-1.16.0.msi)
+
+Note that the MinGW binaries will not work, so make sure that you install the MSVC the ones.
 
 Note that you should ensure that _all_ components are installed from gstreamer, as we require many of the optional libraries that are not installed by default.
 
-4. Install Git for Windows (https://git-scm.com/download/win). DO allow it to add git.exe to the PATH (default
+6. Install Git for Windows (https://git-scm.com/download/win). DO allow it to add git.exe to the PATH (default
 settings for the installer are fine).
 
-5. Install Visual Studio Community 2017 (https://www.visualstudio.com/vs/community/). You MUST add "Visual C++" to the
+7. Install Visual Studio Community 2017 (https://www.visualstudio.com/vs/community/). You MUST add "Visual C++" to the
 list of installed components. It is not on by default. Visual Studio 2017 MUST installed to the default location or mach.bat will not find it.
 
 ##### [Optional] Install LLVM for faster link times

appveyor.yml

@@ -58,7 +58,6 @@ install:
   - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
   - rustup-init.exe -y --default-host x86_64-pc-windows-msvc --default-toolchain none
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  - set PKG_CONFIG_PATH=%PKG_CONFIG_PATH%;C:\gstreamer\1.0\x86_64\lib\pkgconfig
   - rustup -V
   - rustc --version
   - cargo --version

python/servo/build_commands.py

@@ -30,7 +30,7 @@ from mach.decorators import (
 from mach.registrar import Registrar
 
 from mach_bootstrap import _get_exec_path
-from servo.command_base import CommandBase, cd, call, check_call, BIN_SUFFIX, append_to_path_env
+from servo.command_base import CommandBase, cd, call, check_call, BIN_SUFFIX, append_to_path_env, gstreamer_root
 from servo.util import host_triple
 
 
@@ -776,23 +776,6 @@ class MachCommands(CommandBase):
         return True
 
 
-def gstreamer_root(target, env):
-    arch = {
-        "x86_64": "X86_64",
-        "x86": "X86",
-        "aarch64": "ARM64",
-    }
-    gst_x64 = arch[target.split('-')[0]]
-    gst_default_path = path.join("C:\\gstreamer\\1.0", gst_x64)
-    gst_env = "GSTREAMER_1_0_ROOT_" + gst_x64
-    if env.get(gst_env) is not None:
-        return env.get(gst_env)
-    elif os.path.exists(path.join(gst_default_path, "bin", "ffi-7.dll")):
-        return gst_default_path
-    else:
-        return None
-
-
 def package_gstreamer_dlls(env, servo_exe_dir, target, uwp):
     gst_root = gstreamer_root(target, env)
     if not gst_root:

python/servo/command_base.py

@@ -239,6 +239,25 @@ def set_osmesa_env(bin_path, env):
     return env
 
 
+def gstreamer_root(target, env, topdir=None):
+    if is_windows:
+        arch = {
+            "x86_64": "X86_64",
+            "x86": "X86",
+            "aarch64": "ARM64",
+        }
+        gst_x64 = arch[target.split('-')[0]]
+        gst_default_path = path.join("C:\\gstreamer\\1.0", gst_x64)
+        gst_env = "GSTREAMER_1_0_ROOT_" + gst_x64
+        if env.get(gst_env) is not None:
+            return env.get(gst_env)
+        elif os.path.exists(path.join(gst_default_path, "bin", "ffi-7.dll")):
+            return gst_default_path
+    elif sys.platform == "linux2":
+        return path.join(topdir, "support", "linux", "gstreamer", "gst")
+    return None
+
+
 class BuildNotFound(Exception):
     def __init__(self, message):
         self.message = message
@@ -365,9 +384,6 @@ class CommandBase(object):
         build_type = "release" if release else "debug"
         return path.join(base_path, build_type, apk_name)
 
-    def get_gstreamer_path(self):
-        return path.join(self.context.topdir, "support", "linux", "gstreamer", "gst")
-
     def get_binary_path(self, release, dev, target=None, android=False, magicleap=False, simpleservo=False):
         # TODO(autrilla): this function could still use work - it shouldn't
         # handle quitting, or printing. It should return the path, or an error.
@@ -542,7 +558,7 @@ class CommandBase(object):
 
         return self.get_executable(destination_folder)
 
-    def needs_gstreamer_env(self, target):
+    def needs_gstreamer_env(self, target, env):
         try:
             if check_gstreamer_lib():
                 return False
@@ -554,8 +570,8 @@ class CommandBase(object):
         if "x86_64" not in effective_target or "android" in effective_target:
             # We don't build gstreamer for non-x86_64 / android yet
             return False
-        if sys.platform == "linux2":
+        if sys.platform == "linux2" or is_windows:
-            if path.isdir(self.get_gstreamer_path()):
+            if path.isdir(gstreamer_root(effective_target, env, self.get_top_dir)):
                 return True
             else:
                 raise Exception("Your system's gstreamer libraries are out of date \
@@ -569,8 +585,10 @@ install them, let us know by filing a bug!")
     def set_run_env(self, android=False):
         """Some commands, like test-wpt, don't use a full build env,
            but may still need dynamic search paths. This command sets that up"""
-        if not android and self.needs_gstreamer_env(None):
+        if not android and self.needs_gstreamer_env(None, os.environ):
-            gstpath = self.get_gstreamer_path()
+            gstpath = gstreamer_root(host_triple(), os.environ, self.get_top_dir)
+            if gstpath is None:
+                return
             os.environ["LD_LIBRARY_PATH"] = path.join(gstpath, "lib")
             os.environ["GST_PLUGIN_SYSTEM_PATH"] = path.join(gstpath, "lib", "gstreamer-1.0")
             os.environ["PKG_CONFIG_PATH"] = path.join(gstpath, "lib", "pkgconfig")
@@ -624,8 +642,8 @@ install them, let us know by filing a bug!")
             # Always build harfbuzz from source
             env["HARFBUZZ_SYS_NO_PKG_CONFIG"] = "true"
 
-        if self.needs_gstreamer_env(target):
+        if self.needs_gstreamer_env(target or host_triple(), env):
-            gstpath = self.get_gstreamer_path()
+            gstpath = gstreamer_root(target or host_triple(), env, self.get_top_dir())
             extra_path += [path.join(gstpath, "bin")]
             libpath = path.join(gstpath, "lib")
             # we append in the reverse order so that system gstreamer libraries