[C++] Conversion warnings in cast.cc

[asfimport]

This is with gcc 7.3.0 and -Wconversion.

../src/arrow/compute/kernels/cast.cc: In instantiation of ‘void arrow::compute::CastFunctor<O, I, typename std::enable_if<arrow::compute::is_float_truncate<O, I>::value>::type>::operator()(arrow::compute::FunctionContext*, const arrow::compute::CastOptions&, const arrow::ArrayData&, arrow::ArrayData*) [with O = arrow::Int64Type; I = arrow::DoubleType; typename std::enable_if<arrow::compute::is_float_truncate<O, I>::value>::type = void]’:
../src/arrow/compute/kernels/cast.cc:1105:1:   required from here
../src/arrow/compute/kernels/cast.cc:291:45: warning: conversion to ‘in_type {aka double}’ from ‘long int’ may alter its value [-Wconversion]
           if (ARROW_PREDICT_FALSE(out_value != *in_data)) {
                                   ~~~~~~~~~~^~~~~
../src/arrow/util/macros.h:37:50: note: in definition of macro ‘ARROW_PREDICT_FALSE’
 #define ARROW_PREDICT_FALSE(x) (__builtin_expect(x, 0))
                                                  ^
../src/arrow/compute/kernels/cast.cc:301:45: warning: conversion to ‘in_type {aka double}’ from ‘long int’ may alter its value [-Wconversion]
           if (ARROW_PREDICT_FALSE(out_value != *in_data)) {
                                   ~~~~~~~~~~^~~~~
../src/arrow/util/macros.h:37:50: note: in definition of macro ‘ARROW_PREDICT_FALSE’
 #define ARROW_PREDICT_FALSE(x) (__builtin_expect(x, 0))

Reporter: Antoine Pitrou / @pitrou
Assignee: Antoine Pitrou / @pitrou

PRs and other links:

• GitHub Pull Request #2575

_{Note: This issue was originally created as ARROW-3251. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 2575
#2575