Compile error on Intel compiler running in Windows

[ongjunjie]

Unable to compile using Intel compiler in Windows. This is caused by a bug in Hedley nemequ/hedley#39. Opening an issue here to track it.

What is the issue you have?

Can't compile. See Hedley issue for details.

Please describe the steps to reproduce the issue.

1. Build unit tests using combination of Intel compiler and Windows OS

Can you provide a small but working code example?

No.

What is the expected behavior?

Unit tests compiles.

And what is the actual behavior instead?

Build fails.

Which compiler and operating system are you using?

• Compiler: Intel Compiler 18.0
• Operating system: Windows 7

Which version of the library did you use?

• latest release version 3.9.1
• other release - please state the version: ___
• the develop branch

If you experience a compilation error: can you compile and run the unit tests?

• yes
• no - please copy/paste the error message below

..\single_include\nlohmann\json.hpp(2366): error : expected a type specifier
        JSON_HEDLEY_NON_NULL(3)

[nlohmann]

Thanks for reporting! I will create a branch with the new Hedley version to see whether the issue is fixed then.

[ongjunjie]

I did a quick hack by forcing JSON_HEDLEY_INTEL_VERSION to always evaluate false. The compilation passes but linking fails.

unresolved external symbols "__declspec(dllimport) public: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)"

The problem stems from doing a #define private while including standard headers.

json/test/src/unit-convenience.cpp

Lines 32 to 35 in b888afe

	#define private public
	#include <nlohmann/json.hpp>
	using nlohmann::json;
	#undef private

Unfortunately I don't see any quick fix to this issue. Some ideas:

• Rewrite test to use public interfaces instead of private scoped functions
• Include all the standard headers first before doing the #define trick
• Use protected scope instead of private. Protected members can be promoted to public scope in inherited classes.
• Use a macro, for example JSON_private, in place of private in the library, so it can be modified without affecting STL.

[nlohmann]

This is a an issue that keeps coming up. Maybe using a macro for certain instances of private is a good idea. I’ll check.

[nlohmann]

I created PR #2352 for the private/public issue.

[nlohmann]

@ongjunjie I merged #2352. Could you please try if the tests compile now?

[ongjunjie]

Unit tests compiles. Passes all tests only if I pass extra flag /fp:precise to the compiler. Intel by default uses unsafe floating point optimization.

https://software.intel.com/content/www/us/en/develop/documentation/cpp-compiler-developer-guide-and-reference/top/compiler-reference/compiler-options/compiler-option-details/floating-point-options/fp-model-fp.html

[nlohmann]

Very good! I'll wait for the Hedley release. I will also add a note to the README on the /fp:precise flag. Can you tell me which tests fail if the parameter is not set?

[ongjunjie]

Failing tests when compiled without /fp:precise are:

• test-cbor

TEST CASE:  CBOR roundtrips
  input from flynn

• test-msgpack

TEST CASE:  MessagePack roundtrips
  input from msgpack-python

• test-testsuites

TEST CASE:  compliance tests from nativejson-benchmark
  roundtrip

[cppshuli]

hello ,I can not complier with platform Visual Studio 2017 (v141) ,but Visual Studio 2015 (v140) works well.

[nlohmann]

Ok. Hedley 14 is now released (see #2367).

[ongjunjie]

Build and tests passing with latest develop branch. Possible to close this issue.

[nlohmann]

I added a note to the README on flag /fp:precise.