Allow compile with MSVC and Windows headers (#49) #50
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When the boost::pool is instantiated and the code is compiled with MSVC compiler, it can fail if Windows specific headers are included, adding the max and min macros. Because some part of the header file already has preprocessor guards, this change add same solution to call to std::numeric_limits<>::max() to avoid any issues. On MSVC using C++20 standard mode, the header file also fires the same issue, only with include it on code file, without require object instantiation.
| @@ -360,7 +360,7 @@ class pool: protected simple_segregated_storage < typename UserAllocator::size_t | |||
| size_type max_chunks() const | |||
| { //! Calculated maximum number of memory chunks that can be allocated in a single call by this Pool. | |||
| size_type POD_size = integer::static_lcm<sizeof(size_type), sizeof(void *)>::value + sizeof(size_type); | |||
| return (std::numeric_limits<size_type>::max() - POD_size) / alloc_size(); | |||
| return ((std::numeric_limits<size_type>::max)() - POD_size) / alloc_size(); | |||
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Is this a better workaround than the use of BOOST_PREVENT_MACRO_SUBSTITUTION elsewhere in this file?
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I used the same as line 351
pool/include/boost/pool/pool.hpp
Line 351 in e0db427
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I think in use BOOST_PREVENT_MACRO_SUBSTITUTION but it extends the line length and reduce readability.
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I disagree.
The bare parentheses fix the problem, and they're small.
But they give no clue as to why they are there - and that's my concern.
In the future, someone will come along and remove the "redundant" parens.
Hopefully, when that happens, this whole "windows header" thing will be a bad memory.
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Would be great if this could be merged. As when compiling a project with boost 1.82 or 1.83 I run into the following warning many times: C4003: not enough arguments for function-like macro invocation 'max' and this seems to be the culprit.
I also found an issue in another boost lib that addresses the same problem this way:
boostorg/beast@24a1196
Issue it fixed: boostorg/beast#1980.
Would it help to add a comment to explicitly state why those parentheses are there?
When the boost::pool is instantiated and the code is compiled with
MSVC compiler, it can fail if Windows specific headers are included,
adding the max and min macros.
Because some part of the header file already has preprocessor guards,
this change add same solution to call to std::numeric_limits<>::max()
to avoid any issues.
On MSVC using C++20 standard mode, the header file also fires the same
issue, only with include it on code file, without require object
instantiation.