[flang-dev] Difficulties with In-Tree Build of Flang

[Andrzej Warzynski via flang-dev]

Hello Justin,

The new driver will take a while to implement. Internally we are aiming 
for LLVM 12, but that depends on many factors. First we'd like to 
refactor some bits of Clang's driver so that it is easy to re-use them 
in Flang.

- Andrzej


On 24/06/2020 22:50, Steve Scalpone via flang-dev wrote:
> Hi Justin,
> 
> The flang script reads from standard input if a source file is not 
> provided on the command line.  It appears to hang, but it’s really just 
> waiting for input.
> 
> Flang isn’t hooked up to a code generator yet, so instead, by default, 
> flang generates another Fortran source file and tries to compile that 
> file with a different compiler.  The default is pgf90, but you can set 
> the environment variable F18_FC to be a different compiler, like gfortran.
> 
> The flang script that you are running is just a throwaway driver until 
> the real driver is ready.  That work is under development right now, but 
> I don’t know when it will be ready.  Until then, we have this quirky 
> script that lets us test flang semantics.
> 
> - Steve
> 
> *From: *flang-dev <flang-dev-bounces at lists.llvm.org> on behalf of 
> flang-dev <flang-dev at lists.llvm.org>
> *Reply-To: *"Szaday, Justin Josef" <szaday2 at illinois.edu>
> *Date: *Wednesday, June 24, 2020 at 2:02 PM
> *To: *flang-dev <flang-dev at lists.llvm.org>
> *Subject: *[flang-dev] Difficulties with In-Tree Build of Flang
> 
> *External email: Use caution opening links or attachments*
> 
> Hello all,
> 
> I am having a very difficult time getting in-tree builds of Flang 
> working. My build commands are as follows:
> 
> cmake -G Ninja -DLLVM_ENABLE_PROJECTS="flang" 
> -DCMAKE_INSTALL_PREFIX=$(pwd) -DCMAKE_BUILD_TYPE=MinSizeRel ../llvm
> 
> cmake --build . --target check-flang
> 
> cmake --build . --target install
> 
> The build itself completes successfully, and all the Flang tests pass 
> when using “check-flang”; however, “flang -v” and “flang -h” hang (it 
> does not produce any output and has to be killed) and, when trying to 
> compile a program, I get the error message “execvp(pgf90) failed: No 
> such file or directory” (which fails even if I set F18_FC to gfortran or 
> flang). I have tried building it on a few machines to no avail. I have 
> tested both the Debug and MinSizeRel build types, used both Ninja and 
> Unix Makefiles to build it, and tested a few different versions of 
> GCC/G++, ultimately settling on v9.1.0. I am building from master of the 
> llvm-project GitHub repository.
> 
> Any insights here would be appreciated, I am at a loss about what else 
> to try here. Any other debugging suggestions or usage tips would be 
> appreciated as well.
> 
> Thanks,
> 
> Justin
> 
> 
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