Fix Travis TSAN build

Travis upgraded the trusty image that tests use and it broke our TSAN
tests. TSAN does not work for pie binaries on the upgraded OS. See
google/sanitizers#503
The fix is to use gcc-5 and non-pie binaries.

Change-Id: I9b972f1c08fb7408d5bcc54b403660c1255a11d5

.travis.yml

@@ -11,6 +11,9 @@ addons:
     packages:
       - g++-4.8
       - gcc-4.8
+      # We need gcc-5 for TSAN. See comments in tools/bazel.rc.
+      - g++-5
+      - gcc-5
       - lcov
       - libio-socket-ssl-perl
       - oracle-java8-installer
@@ -30,8 +33,8 @@ env:
     - SCENARIO="build-and-test"
     # Build & run the tests with ASAN enabled
     - SCENARIO="asan"
-    # Build & run the tests with TSAN enabled
-    - SCENARIO="tsan"
+    # Build & run the tests with TSAN enabled (using gcc-5)
+    - SCENARIO="tsan" CC=gcc-5 CXX=g++-5
     # Build & run the tests & generate coverage report
     - SCENARIO="coverage"
     # Build & run docker tests

script/presubmits

@@ -73,6 +73,10 @@ function tsan() {
   build_and_test 'tsan' || return 1
 }
 
+function tsan_nopie() {
+  build_and_test 'tsan_nopie' || return 1
+}
+
 function release() {
   build_and_test 'release' || return 1
 }

script/travis/run

@@ -36,7 +36,7 @@ SCENARIO="$1"
 case $SCENARIO in
   build-and-test) build_and_test || error_exit "Build and Tests failed";;
   asan) asan || error_exit "ASAN tests failed";;
-  tsan) tsan || error_exit "TSAN tests failed";;
+  tsan) tsan_nopie || error_exit "TSAN tests failed";;
   coverage) coverage || error_exit "Coverage failed";;
   docker-tests) docker_tests || error_exit "Docker tests failed";;
   *) error_exit "Usage: travis-run build-and-test|asan|tsan|coverage|docker-tests";;

tools/bazel.rc

@@ -16,10 +16,21 @@ build:tsan --copt -fno-omit-frame-pointer
 build:tsan --linkopt -fsanitize=thread
 build:tsan --linkopt -pie
 # Use -Wl,-ltsan instead of -ltsan to make Bazel link libtsan before all other
-# libs. TSAN on Ubuntu 12.04 (used by Travis) doesn't work if -lpthread is
-# specified before -ltsan.
+# libs in particularly before -lpthread. This allows TSAN to pull in it's own
+# version of -lpthread.
 build:tsan --linkopt -Wl,-ltsan
 
+# Our default TSAN setup with -pie does not work with some linux versions (e.g.,
+# on Travis's trusty). See https://github.com/google/sanitizers/issues/503
+# So for TSAN on Travis we use gcc-5, which supports TSAN for non-pie binaries.
+build:tsan_nopie --strip=never
+build:tsan_nopie --copt -fsanitize=thread
+build:tsan_nopie --copt -O2
+build:tsan_nopie --copt -g
+build:tsan_nopie --copt -fno-omit-frame-pointer
+build:tsan_nopie --linkopt -fsanitize=thread
+build:tsan_nopie --linkopt -Wl,-ltsan
+
 # Release builds
 build:release -c opt