Bug 1394825 - Update minimum clang version to 4.0. r=glandium

libclang 3.9 has a bug that makes bindgen unable to distinguish some typedefs
from the underlying type, which matters for bug 1523071.

We have had quite a few workarounds for this bug and I don't really want to add
more, since in this case it is non-trivial. I think requiring libclang 4.0+ is
reasonable at this point.

Of the distros that can't build Firefox out of the box with clang, dropping support
for clang 3.9 would only break Ubuntu 14.04 LTS, which support ends April 2019,
right before we release 67.

Differential Revision: https://phabricator.services.mozilla.com/D18889

--HG--
rename : build/build-clang/clang-3.9-linux64.json => build/build-clang/clang-4.0-linux64.json
rename : taskcluster/scripts/misc/build-clang-3.9-linux.sh => taskcluster/scripts/misc/build-clang-4.0-linux.sh
extra : moz-landing-system : lando

build/build-clang/clang-4.0-linux64.json

@@ -1,24 +1,18 @@
 {
-    "llvm_revision": "289595",
+    "llvm_revision": "305830",
     "stages": "3",
     "build_libcxx": true,
     "build_type": "Release",
     "assertions": false,
-    "llvm_repo": "https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_391/final",
-    "clang_repo": "https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_391/final",
-    "compiler_repo": "https://llvm.org/svn/llvm-project/compiler-rt/tags/RELEASE_391/final",
-    "libcxx_repo": "https://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_391/final",
-    "libcxxabi_repo": "https://llvm.org/svn/llvm-project/libcxxabi/tags/RELEASE_391/final",
+    "llvm_repo": "https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_401/final",
+    "clang_repo": "https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_401/final",
+    "compiler_repo": "https://llvm.org/svn/llvm-project/compiler-rt/tags/RELEASE_401/final",
+    "libcxx_repo": "https://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_401/final",
+    "libcxxabi_repo": "https://llvm.org/svn/llvm-project/libcxxabi/tags/RELEASE_401/final",
     "python_path": "/usr/bin/python2.7",
     "gcc_dir": "/builds/worker/workspace/build/src/gcc",
     "cc": "/builds/worker/workspace/build/src/gcc/bin/gcc",
     "cxx": "/builds/worker/workspace/build/src/gcc/bin/g++",
     "as": "/builds/worker/workspace/build/src/gcc/bin/gcc",
-    "patches": [
-      "llvm-debug-frame.patch",
-      "r277806.patch",
-      "r285657.patch",
-      "r289565-for-3.9.patch",
-      "r313872.patch"
-    ]
+    "patches": []
 }

taskcluster/ci/build/linux.yml

@@ -271,7 +271,7 @@ linux64-base-toolchains/opt:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
-        - linux64-clang-3.9
+        - linux64-clang-4.0
         - linux64-gcc-6
         - linux64-rust-1.31
         - linux64-cbindgen
@@ -306,7 +306,7 @@ linux64-base-toolchains/debug:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
-        - linux64-clang-3.9
+        - linux64-clang-4.0
         - linux64-gcc-6
         - linux64-rust-1.31
         - linux64-cbindgen
@@ -338,7 +338,7 @@ linux64-base-toolchains-clang/opt:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
-        - linux64-clang-3.9
+        - linux64-clang-4.0
         - linux64-rust-1.31
         - linux64-cbindgen
         - linux64-sccache
@@ -371,7 +371,7 @@ linux64-base-toolchains-clang/debug:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
-        - linux64-clang-3.9
+        - linux64-clang-4.0
         - linux64-rust-1.31
         - linux64-cbindgen
         - linux64-sccache

taskcluster/ci/toolchain/clang.yml

@@ -10,15 +10,15 @@ job-defaults:
         resources:
             - 'build/build-clang/build-clang.py'
 
-linux64-clang-3.9:
-    description: "Clang 3.9 toolchain build"
+linux64-clang-4.0:
+    description: "Clang 4.0 toolchain build"
     treeherder:
-        symbol: TL(clang3.9)
+        symbol: TL(clang4.0)
     worker-type: aws-provisioner-v1/gecko-{level}-b-linux-large
     run:
-        script: build-clang-3.9-linux.sh
+        script: build-clang-4.0-linux.sh
         resources:
-            - 'build/build-clang/clang-3.9-linux64.json'
+            - 'build/build-clang/clang-4.0-linux64.json'
             - 'taskcluster/scripts/misc/tooltool-download.sh'
         toolchain-artifact: public/build/clang.tar.xz
     toolchains:

taskcluster/scripts/misc/build-clang-4.0-linux.sh

@@ -16,7 +16,7 @@ set +x
 
 cd build/build-clang
 # |mach python| sets up a virtualenv for us!
-../../mach python ./build-clang.py -c clang-3.9-linux64.json
+../../mach python ./build-clang.py -c clang-4.0-linux64.json
 
 set -x