[BUG] `e is func` is false

[ntrel]

Describe the bug
With cppfront from git ecd3726 and g++ (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0:

pred: (x: int) -> int = x < 20;

main: () = 
{
    p2 := :(x) -> _ = x < 20;
    b := 5 is (p2); // true
    std::cout << b << "\n";
    b = 5 is (pred); // false
    std::cout << b << "\n";
}

I expected both is expressions to produce true, but the second one is false.

A secondary problem is that rewriting pred to be a template fails to compile:

pred: (x) -> _ = x < 20;

lessthan.cpp2:48:17: error: no matching function for call to ‘is(int, <unresolved overloaded function type>)’
... snip candidates ...

[JohelEGP]

The reason seems to be

cppfront/include/cpp2util.h

Line 883 in ecd3726

else if constexpr (requires{ bool{ value(x) }; }) {

pred returns an int, so bool{pred(5)} is narrowing, and the requires-expression evaluates to false.

[ntrel]

Oops, thanks! So this definition works:

pred: (x: int) -> _ = x < 20;

The remaining problem is if I don't specify a type for x then it doesn't compile.

[filipsajdak]

I am currently working on is improvements. I will push it soon.

[filipsajdak]

OK, I have solved also the generic function case.