ddd2747b7e
The update stems from the discussion in https://discourse.llvm.org/t/adding-flang-specific-header-files-to-clang/72442 This is my third attempt at this. My second attempt was in pull request #69121. This is my second attempt at this. My first attempt was in pull request #68756. This pull request has three changes from the second one: - I put the test into the Driver directory rather than Examples so that it would get run without require the define LLVM_BUILD_EXAMPLES. - When installing ISO_Fortran_binding.h, I changed the location where it was installed from. - I changed the test so that it would work when flang was built with shared libraries. Here's the information from my previous attempts: I decided to put ISO_Fortran_binding.h in a place where it would be accessible with the include: "#include<ISO_Fortran_binding.h>" rather than "#include<fortran/ISO_Fortran_binding.h>" because this is what gfortran implements. Note that the file is also installed into ".../include/flang", so if a user wanted to access the file from a compiler other than clang, it would be available. I added a test in ".../flang/test/Driver". To make the test work, I also needed to put ISO_Fortran_binding.h into the build area. Although the flang project depends on clang, clang may not always be available in a flang build. For example, when building just the "check-flang" target, the "clang" executable may not be available at the time the new test gets run. To account for this, I made the test's script check for the existence of the "clang" executable. If "clang" is not available, it simply prints "PASS". If it is available, it fully builds and executes the test. On success, this will also print "PASS"
Flang
Flang is a ground-up implementation of a Fortran front end written in modern C++. It started off as the f18 project (https://github.com/flang-compiler/f18) with an aim to replace the previous flang project (https://github.com/flang-compiler/flang) and address its various deficiencies. F18 was subsequently accepted into the LLVM project and rechristened as Flang.
Please note that flang is not ready yet for production usage.
Getting Started
Read more about flang in the docs directory. Start with the compiler overview.
To better understand Fortran as a language and the specific grammar accepted by flang, read Fortran For C Programmers and flang's specifications of the Fortran grammar and the OpenMP grammar.
Treatment of language extensions is covered in this document.
To understand the compilers handling of intrinsics, see the discussion of intrinsics.
To understand how a flang program communicates with libraries at runtime, see the discussion of runtime descriptors.
If you're interested in contributing to the compiler, read the style guide and also review how flang uses modern C++ features.
If you are interested in writing new documentation, follow LLVM's Markdown style guide.
Consult the Getting Started with Flang for information on building and running flang.