[flang][OpenMP] Wrong or unclear error message for Fujitsu test 0481_0038

[eugeneepshteyn]

When compiling Fujitsu test 0481_0038.f90 with OpenMP, get the following error:

$ flang -c -fopenmp 0481_0038.f90 
flang-21: warning: OpenMP support in flang is still experimental [-Wexperimental-option]
error: Semantic errors in 0481_0038.f90
./0481_0038.f90:9:4: error: The atomic variable yy should occur exactly once among the arguments of the top-level MAX operator
  yy=max(1,1,1 ,yy+1)
     ^^^^^^^^^^^^^^^^

Well, it seems that yy occurs exactly once among the arguments of max. Either this check is incorrect, or the the error message needs to describe the problem better.

This error started happening between commits 28a4ed9 (known good) and e64f8e0 (first discovered bad). I haven't done a bisect, but 141d390 looks like a candidate commit.

[eugeneepshteyn]

Tagging @kparzysz

[kparzysz]

I'll improve the error message. The test itself is erroneous (see fujitsu/compiler-test-suite#28).

[kparzysz]

Would The atomic variable yy should be exactly one of the arguments of the top-level MAX operator be clearer?

[eugeneepshteyn]

I think the way you described it in the Fujitsu bug makes it more clear: "... by itself be an argument to an intrinsic function, not as a part of another expression"

So the message could be The atomic variable yy should itself be one of the arguments of the top-level MAX operator, not as part of another expression.

[kparzysz]

Yeah, I'm going to rework that check to make it more detailed.