Enable C++ coverage (apache#12642)

* Enable C++ coverage for make

* Enable C++ test coverage for CMake

* Add environment variable GCOV_PREFIX

* Stash GCNO files

* Enable test coverage for Scala

* Fix -P not found error

* Remove debug comments

* Add linking with coverage

* Trigger separate build

* Add ignored files

.codecov.yml

@@ -21,6 +21,10 @@ parsers:
       method: no
       macro: no
 
+ignore:
+ - "cpp-package/example/**/*"
+ - "tests/**/*"
+
 # Disable comments for now to gather data in the background
 comment: false
 #  layout: "header, diff"

.gitignore

@@ -169,4 +169,11 @@ tests/mxnet_unit_tests
 
 # generated wrappers for ccache
 cc
-cxx
+cxx
+
+# Code coverage related
+.coverage
+*.gcov
+*.gcno
+coverage.xml
+

CMakeLists.txt

@@ -39,6 +39,7 @@ mxnet_option(INSTALL_EXAMPLES     "Install the example source files." OFF)
 mxnet_option(USE_SIGNAL_HANDLER   "Print stack traces on segfaults." OFF)
 mxnet_option(USE_TENSORRT         "Enable infeference optimization with TensorRT." OFF)
 mxnet_option(USE_ASAN             "Enable Clang/GCC ASAN sanitizers." OFF)
+mxnet_option(ENABLE_TESTCOVERAGE  "Enable compilation with test coverage metric output" OFF)
 
 message(STATUS "CMAKE_SYSTEM_NAME ${CMAKE_SYSTEM_NAME}")
 if(USE_CUDA AND NOT USE_OLDCMAKECUDA)
@@ -218,6 +219,20 @@ if(USE_TENSORRT)
           ${ONNX_PROTO_LIBRARY} ${ONNX_LIBRARY} ${PROTOBUF_LIBRARY})
 endif()
 
+if(ENABLE_TESTCOVERAGE)
+  message(STATUS "Compiling with test coverage support enabled. This will result in additional files being written to your source directory!")
+  find_program( GCOV_PATH gcov )
+  if(NOT GCOV_PATH)
+    message(FATAL_ERROR "gcov not found! Aborting...")
+  endif() # NOT GCOV_PATH
+
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --coverage")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage")
+  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} --coverage")
+  set(GTEST_LIBRARIES "${GTEST_LIBRARIES} --coverage")
+  link_libraries(gcov)
+endif()
+
 if(USE_MKLDNN)
   include(cmake/MklDnn.cmake)
   # CPU architecture (e.g., C5) can't run on another architecture (e.g., g3).