Clang update script: download pre-built modern gcc and CMake if necessary

tools/clang/scripts/update.sh

 #!/usr/bin/env bash
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script will check out llvm and clang into third_party/llvm and build it.
 
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://code.google.com/p/chromium/wiki/UpdatingClang
 # Reverting problematic clang rolls is safe, though.
@@ skipping 16 matching lines @@
 ABS_CHROMIUM_TOOLS_DIR="${PWD}/${CHROMIUM_TOOLS_DIR}"
 ABS_LIBCXX_DIR="${PWD}/${LIBCXX_DIR}"
 ABS_LIBCXXABI_DIR="${PWD}/${LIBCXXABI_DIR}"
 ABS_LLVM_DIR="${PWD}/${LLVM_DIR}"
 ABS_LLVM_BUILD_DIR="${PWD}/${LLVM_BUILD_DIR}"
 ABS_COMPILER_RT_DIR="${PWD}/${COMPILER_RT_DIR}"
 
 # ${A:-a} returns $A if it's set, a else.
 LLVM_REPO_URL=${LLVM_URL:-https://llvm.org/svn/llvm-project}
 
+CDS_URL=https://commondatastorage.googleapis.com/chromium-browser-clang
+
 if [[ -z "$GYP_DEFINES" ]]; then
   GYP_DEFINES=
 fi
 if [[ -z "$GYP_GENERATORS" ]]; then
   GYP_GENERATORS=
 fi
 
 
 # Die if any command dies, error on undefined variable expansions.
 set -eu
@@ skipping 107 matching lines @@
   force_local_build=yes
 
   # Skip local patches when using HEAD: they probably don't apply anymore.
   with_patches=
 
   if ! [[ "$GYP_DEFINES" =~ .*OS=android.* ]]; then
     # Only build the Android ASan rt when targetting Android.
     with_android=
   fi
 
-  if [[ "${OS}" == "Linux" ]] && [[ -z ${gcc_toolchain:-''} ]]; then
-    # Set gcc_toolchain on Linux; llvm-symbolizer needs the bundled libstdc++.
-    gcc_toolchain="$(dirname $(dirname $(which gcc)))"
+  LLVM_BUILD_TOOLS_DIR="${ABS_LLVM_DIR}/../llvm-build-tools"
+
+  if [[ "${OS}" == "Linux" ]] && [[ -z "${gcc_toolchain}" ]]; then
+    if [[ $(gcc -dumpversion) < "4.7.0" ]]; then
+      # We need a newer GCC version.
+      if [[ ! -e "${LLVM_BUILD_TOOLS_DIR}/gcc482" ]]; then

[Nico, 2015/03/05 03:55:18]

This if seems to not work for some reason, looks like the bots download stuff on
every run.

+        echo "Downloading pre-built GCC 4.8.2"
+        mkdir -p "${LLVM_BUILD_TOOLS_DIR}"
+        curl --fail -L "${CDS_URL}/tools/gcc482.tgz" | \
+          tar vzxf - -C "${LLVM_BUILD_TOOLS_DIR}"
+      fi
+      gcc_toolchain="${LLVM_BUILD_TOOLS_DIR}/gcc482"
+    else
+      # Always set gcc_toolchain; llvm-symbolizer needs the bundled libstdc++.
+      gcc_toolchain="$(dirname $(dirname $(which gcc)))"
+    fi
+  fi
+
+  if [[ "${OS}" == "Linux" ]]; then
+    # TODO(hans): Might need to make this work on Mac eventually.
+    if [[ $(cmake --version | grep -Eo '[0-9.]+') < "3.0" ]]; then
+      # We need a newer CMake version.
+      if [[ ! -e "${LLVM_BUILD_TOOLS_DIR}/cmake310" ]]; then
+        echo "Downloading pre-built CMake 3.10"
+        mkdir -p "${LLVM_BUILD_TOOLS_DIR}"
+        curl --fail -L "${CDS_URL}/tools/cmake310.tgz" | \
+          tar vzxf - -C "${LLVM_BUILD_TOOLS_DIR}"
+      fi
+      export PATH="${LLVM_BUILD_TOOLS_DIR}/cmake310/bin:${PATH}"

[Nico, 2015/03/05 03:58:39]

…and this should probably run before the `cmake --version` line. If the
directory doesn't exist the if will then be entered if cmake is too old, and
won't be entered if cmake was already downloaded before

+    fi
   fi
 
   echo "LLVM_FORCE_HEAD_REVISION was set; using r${CLANG_REVISION}"
 fi
 
 if [[ -n "$if_needed" ]]; then
   if [[ "${OS}" == "Darwin" ]]; then
     # clang is used on Mac.
     true
   elif [[ "$GYP_DEFINES" =~ .*(clang|tsan|asan|lsan|msan)=1.* ]]; then
@@ skipping 26 matching lines @@
     exit 0
   fi
 fi
 # To always force a new build if someone interrupts their build half way.
 rm -f "${STAMP_FILE}"
 
 
 if [[ -z "$force_local_build" ]]; then
   # Check if there's a prebuilt binary and if so just fetch that. That's faster,
   # and goma relies on having matching binary hashes on client and server too.
-  CDS_URL=https://commondatastorage.googleapis.com/chromium-browser-clang
   CDS_FILE="clang-${CLANG_REVISION}.tgz"
   CDS_OUT_DIR=$(mktemp -d -t clang_download.XXXXXX)
   CDS_OUTPUT="${CDS_OUT_DIR}/${CDS_FILE}"
   if [ "${OS}" = "Linux" ]; then
     CDS_FULL_URL="${CDS_URL}/Linux_x64/${CDS_FILE}"
   elif [ "${OS}" = "Darwin" ]; then
     CDS_FULL_URL="${CDS_URL}/Mac/${CDS_FILE}"
   fi
   echo Trying to download prebuilt clang
   if which curl > /dev/null; then
@@ skipping 745 matching lines @@
 
 if [[ -n "$run_tests" ]]; then
   # Run Chrome tool tests.
   ninja -C "${LLVM_BUILD_DIR}" cr-check-all
   # Run the LLVM and Clang tests.
   ninja -C "${LLVM_BUILD_DIR}" check-all
 fi
 
 # After everything is done, log success for this revision.
 echo "${CLANG_AND_PLUGINS_REVISION}" > "${STAMP_FILE}"