| Issue |
131088
|
| Summary |
[flang] COMPLEX*32 works but COMPLEX(real128) - Open MPI build fails
|
| Labels |
flang
|
| Assignees |
|
| Reporter |
hakostra
|
I encountered a problem building Open MPI 5.0.7 with a newly compiled `flang` from git sources, reported here: https://github.com/open-mpi/ompi/issues/13136
The version of `flang` I built is:
```
flang version 21.0.0git (https://github.com/llvm/llvm-project.git 5d50af3f0368847ab9ce1d86cb6e46ffaf317b59)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/llvm/llvm-project/install/bin
```
The problem is in short that variable declarations `COMPLEX(real128)` does not work, take the following as an example:
```
PROGRAM real128test
USE iso_fortran_env, ONLY: real128
IMPLICIT NONE (type, external)
COMPLEX(real128) :: test
test = CMPLX(1.0, 2.0)
WRITE(*, *) "test: ", test
WRITE(*, *) "storage_size: ", storage_size(test)
END PROGRAM real128test
```
Compiling this I get:
```
error: Semantic errors in real128.F90
./real128.F90:5:5: error: COMPLEX(KIND=-1) is not a supported type
COMPLEX(real128) :: test
```
However, the similar example, using COMPLEX*32, works:
```
PROGRAM complextest
IMPLICIT NONE (type, external)
COMPLEX*32 test
test = CMPLX(1.0, 2.0)
WRITE(*, *) "test: ", test
WRITE(*, *) "storage_size: ", storage_size(test)
END PROGRAM complextest
```
Giving me the output:
```
$ flang complex32.F90
$ ./a.out
test: (1.,2.)
storage_size: 256
```
Which I think is a bit weird. In my mind, `COMPLEX*32` and `COMPLEX(real128)` should be the same type, but maybe I'm wrong...
So it seems my `flang` was compiled without support for `real128`, which is fine, I don't need it. However, I find it strange that `COMPLEX*32` works in this scenario. A side-note is that I have attempted to build `flang` wit OpenMP offloading support, maybe that is why `real128` is disabled.
So the reason the Open MPI build fails, is that it checks for the support of `COMPLEX*32` with some simple test, then, if this is support is present, it goes ahead and use `COMPLEX(real128)` as if these two declarations are equivalent. This does not work and the build fails.
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