[ARROW-1615] CXX flags for development more permissive than Travis CI builds

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.8.0
• Component/s: C++
• Labels: pull-request-available
• Flags: Patch
• External issue URL: https://github.com/apache/arrow/issues/17626
• Assignee: Rene Sugar
• Reporter: Rene Sugar
• Created: 27/Sep/17 01:05
• Updated: 11/Jan/23 07:15
• Resolved: 30/Sep/17 18:31

Description

arrow/cpp/cmake_modules/SetupCxxFlags.cmake uses more permissive CXX flags than the Travis CI integration build.

A project that builds without warnings or errors on a development machine can break during a Travis build.

Those using CLang and GNU may not see the same warnings before a check-in.

Travis CI:

-Wall -std=c11 -Wconversion -Wno-sign-conversion -Werror -std=gnu+11

Arrow:

-Wall -std=c+11 -std=gnu+11

Parquet-CPP:

-Wall -std=gnu++11

With only CLang installed, g++ is a wrapper for CLang.

To make it less likely that a Clang build will break when checked-in, CLang has a -Weverything flag from which specific warnings can be disabled and enabled.

http://amattn.com/p/better_apps_clang_weverything_or_wall_is_a_lie.html

https://gcc.gnu.org/wiki/ClangDiagnosticsComparison

https://github.com/Barro/compiler-warnings

However, the warning that caused this particular build failure is specific to GNU gcc.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40752

https://stackoverflow.com/questions/12641387/is-gccs-wconversion-incompatible-with-the-use-of-compound-assignment-etc

CLang has a "-Weverything" flag. Individual warnings were disabled until the current Arrow source code compiled without errors.

Individual warnings can be enabled when using the CLang compiler to see if there is anything that needs to be fixed.

```
elseif((CMAKE_CXX_COMPILER_ID STREQUAL "Clang") OR (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang"))

1. NOTE: -Wconversion does not return the same warnings on CLang and GNU (build can still fail even when enabled)
   set(CXX_COMMON_FLAGS "-Weverything -Wno-c+98-compat -Wno-c98-compat-pedantic -Wno-deprecated -Wno-weak-vtables -Wno-padded -Wno-unused-parameter -Wno-undef -Wno-documentation-deprecated-sync -Wno-reserved-id-macro -Wno-shadow -Wno-switch-enum -Wno-documentation -Wno-exit-time-destructors -Wno-global-constructors -Wno-weak-template-vtables -Wno-undefined-reinterpret-cast -Wno-implicit-fallthrough -Wno-old-style-cast -Wno-unreachable-code-return -Wno-float-equal -Wno-missing-prototypes -Wno-double-promotion -Wno-non-virtual-dtor -Wno-unused-macros -Wno-covered-switch-default -Wno-unreachable-code-break -Wno-extra-semi -Wno-range-loop-analysis -Wno-shift-sign-overflow -Wno-used-but-marked-unused -Wno-missing-variable-declarations -Wno-gnu-zero-variadic-macro-arguments -Wconversion -Wno-sign-conversion -Wc11-narrowing -Wnarrowing -Werror -std=c+11")
   else()
2. Travis CI builds use these flags
   set(CXX_COMMON_FLAGS "-Wall -Wconversion -Wno-sign-conversion -Werror -std=c++11")
   endif()
   ```

```
In file included from /home/travis/build/apache/arrow/cpp/src/arrow/buffer.h:29:0,
from /home/travis/build/apache/arrow/cpp/src/arrow/buffer.cc:18:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h: In member function ‘void arrow::internal::BitmapWriter::Set()’:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h:108:30: error: conversion to ‘uint8_t

{aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion]
void Set() { current_byte_ |= (1 << bit_offset_); }
^
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h: In member function ‘void arrow::internal::BitmapWriter::Clear()’:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h:110:32: error: conversion to ‘uint8_t {aka unsigned char}

’ from ‘int’ may alter its value [-Werror=conversion]
void Clear()

{ current_byte_ &= ~(1 << bit_offset_); }
^
cc1plus: all warnings being treated as errors
[28/137] Building CXX object CMakeFiles/arrow_objlib.dir/src/arrow/array.cc.o
FAILED: CMakeFiles/arrow_objlib.dir/src/arrow/array.cc.o
/usr/bin/ccache /usr/lib/ccache/g+-4.9 -DARROW_EXTRA_ERROR_CONTEXT -DARROW_NO_DEPRECATED_API -DARROW_WITH_BROTLI -DARROW_WITH_LZ4 -DARROW_WITH_SNAPPY -DARROW_WITH_ZLIB -DARROW_WITH_ZSTD -isystem /home/travis/build/apache/arrow/cpp-toolchain/include -isystem googletest_ep-prefix/src/googletest_ep/include -isystem gbenchmark_ep/src/gbenchmark_ep-install/include -isystem /home/travis/build/apache/arrow/cpp/thirdparty/hadoop/include -I/home/travis/build/apache/arrow/cpp/src -ggdb -O0 -Wall -std=c11 -msse3 -Wconversion -Wno-sign-conversion -Werror -g -fPIC -std=gnu+11 -MD -MT CMakeFiles/arrow_objlib.dir/src/arrow/array.cc.o -MF CMakeFiles/arrow_objlib.dir/src/arrow/array.cc.o.d -o CMakeFiles/arrow_objlib.dir/src/arrow/array.cc.o -c /home/travis/build/apache/arrow/cpp/src/arrow/array.cc
In file included from /home/travis/build/apache/arrow/cpp/src/arrow/buffer.h:29:0,
from /home/travis/build/apache/arrow/cpp/src/arrow/array.h:27,
from /home/travis/build/apache/arrow/cpp/src/arrow/array.cc:18:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h: In member function ‘void arrow::internal::BitmapWriter::Set()’:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h:108:30: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion]
void Set() { current_byte_ |= (1 << bit_offset_); }
^
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h: In member function ‘void arrow::internal::BitmapWriter::Clear()’:
/home/travis/build/apache/arrow/cpp/src/arrow/util/bit-util.h:110:32: error: conversion to ‘uint8_t {aka unsigned char}’ from ‘int’ may alter its value [-Werror=conversion]
void Clear() { current_byte_ &= ~(1 << bit_offset_); }

^
cc1plus: all warnings being treated as errors
```

Issue Links

• links to: GitHub Pull Request #1145