![\"\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2022\/06\/TimelineCpp20Ranges.png\")
<\/p>\nThanks to the module interface unit and implementation unit, you can separate the interface from the implementation when defining a module. Let me show you how.<\/p>\n
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As promised in my last post, C++20: A Simple math Modul<\/a>, I want to make a short detour on my Clang Odyssee. My detour is a compact refresher to all I wrote in the referred post.<\/p>\n First, I don’t want to blame anyone but myself. Based on talks from Boris Kolpackov “Building C++ Modules<\/a>” at the CppCon 2017 or Corentin Jabot “Modules are not a tooling opportunity<\/a>” I had the impression that the vendors suggested the following extensions for their module definition:<\/p>\n In the case of the Clang compiler, I was wrong. This is my simple math<\/span> module, which I tried to compile with the Clang compiler.<\/p>\n I tried to compile the module with Clang 9 and Clang 10 on Microsoft and Linux. I tried to compile it with the brand-new Clang 11 compiler, built from the sources. Here is one of my many tries.<\/p>\n This command line should create the module math.pcm<\/span>. I specified in the command line -std=c++20 -fmodules-ts<\/span><\/strong> and the error message said: module interface compilation requires ‘-std=c++20′ or ‘-fmodules-ts’<\/strong><\/span>.\u00a0 I made all variations of the two flags, added the global module fragment to the module definition, and invoked the Clang compiler with additional flags, but the result was always the same.<\/p>\nMy Clang Odyssey<\/h2>\n
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\n\/\/ math.cppm<\/span>\n\nexport<\/span> module math;\n\nexport<\/span> int<\/span> add<\/span>(int<\/span> fir, int<\/span> sec){\n return<\/span> fir +<\/span> sec;\n} \n<\/pre>\n<\/div>\n![\"ClangError\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2020\/05\/ClangError.png\")
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![\"clang\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2018\/01\/clang.png\")
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