Applying parens to .re/.im results in an internal error

[bradcray]

Summary of Problem

Description:

When calling .re or .im on an expression with type complex, an internal error is generated. A user-facing error should presumably be generated instead.

var c: complex = 1.2 + 3.4i;

writeln(c.re());  // generates an internal error

In developer mode, the internal error is of the form:

internal error: Cannot call insertAfter on Expr not in a list [AST/expr.cpp:404]

Interestingly, this doesn't happen for user-defined paren-less methods, suggesting it's something special about complexes or these methods, as built-ins:

record R {
  proc foo {   // similar result whether this is returning a literal, as here, or a ref or const ref to a field
    writeln("In R.foo");
    return 4.2;
  }
}

var myR = new R();
writeln(myR.foo());  // generates a user-facing error as expected

Steps to Reproduce

Associated Future Test(s):
test/types/complex/parenfulReIm.chpl #26262

Configuration Information

• Output of chpl --version: chpl version 2.3.0 pre-release (10cc4042fd)

[jabraham17]

I can replicate this with a user defined parenless method. Having two overloaded parenless methods with differing return intents seems to be the root cause.

record R {}
var r = new R();
var myConstant = 1.0;

proc R.foo {
  return myConstant;
}
proc R.foo ref {
  return myConstant;
}

r.foo();

[bradcray]

Aha, thanks for that insight, Jade! I thought I was being very clever for thinking of return intents at all, but gave up too soon…

[DanilaFe]

Taking look as a little treat for myself :)

[DanilaFe]

I've got a fix with the associated tests (#26275); if that merges before #26262, please consider not including the future :)

[bradcray]

Thanks Daniel! I can just close my PR is you prefer.