Firestore CMake cleanup (#1510)

* Pull out sanitizer options into a separate file

* Reorder packages

* Remove the extra "external/$target" directory from PREFIX

Instead of BINARY_DIR/external/foo/src/foo the contents will be in
BINARY_DIR/src/foo.

* Make libprotobuf-nanopb targets line up with nanopb's CMakeLists.txt

* Fix CMake style

1 files changed, 57 insertions, 0 deletions

diff --git a/cmake/SanitizerOptions.cmake b/cmake/SanitizerOptions.cmake
new file mode 100644
index 0000000..4106221
--- /dev/null
+++ b/cmake/SanitizerOptions.cmake
@@ -0,0 +1,57 @@
+# Copyright 2018 Google
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Adds Sanitzer options to the current build.
+
+option(WITH_ASAN "Build with Address Sanitizer" OFF)
+# TODO(varconst): msan
+# Memory sanitizer is more complicated:
+# - it requires all dependencies to be compiled with msan enabled (see
+#   https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo);
+# - AppleClang doesn't support it.
+option(WITH_TSAN "Build with Thread Sanitizer (mutually exculsive with other sanitizers)" OFF)
+option(WITH_UBSAN "Build with Undefined Behavior sanitizer" OFF)
+
+macro(add_to_compile_and_link_flags flag)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${flag}")
+endmacro()
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+  if(WITH_ASAN)
+    add_to_compile_and_link_flags("-fsanitize=address")
+  endif()
+
+  if(WITH_TSAN)
+    if(WITH_ASAN OR WITH_UBSAN)
+      message(FATAL_ERROR "Cannot combine TSan with other santizers")
+    endif()
+    add_to_compile_and_link_flags("-fsanitize=thread")
+  endif()
+
+  if(WITH_UBSAN)
+    add_to_compile_and_link_flags("-fsanitize=undefined")
+  endif()
+
+  if (WITH_ASAN OR WITH_TSAN OR WITH_UBSAN)
+    # Recommended to "get nicer stack traces in error messages"
+    # TODO(varconst): double-check that TSan actually needs this flag (it's
+    # explicitly recommended in the docs for ASan and UBSan)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-omit-frame-pointer")
+  endif()
+else()
+  if(WITH_ASAN OR WITH_TSAN OR WITH_UBSAN)
+    message(FATAL_ERROR "Only Clang and GCC support sanitizers")
+  endif()
+endif()