@call does not work within inline loops

[pfgithub]

Zig 0.6.0+d44c9bdbd on Linux x64

When using @call within an inlined loop that loops at least twice, it errors:

./test.zig:13:16: error: cannot assign to constant
        @call(.{}, write, .{}); //<- cannot asssign to constant
               ^
./test.zig:3:29: note: referenced here
pub fn main() anyerror!void {
                            ^
./test.zig:13:16: error: cannot assign to constant
        @call(.{}, write, .{}); //<- cannot asssign to constant
               ^
./test.zig:26:16: error: cannot assign to constant
        @call(.{}, write, .{}); //<- cannot asssign to constant
               ^
./test.zig:26:16: error: cannot assign to constant
        @call(.{}, write, .{}); //<- cannot asssign to constant
               ^

test.zig:

const std = @import("std");
fn write() void {}
pub fn main() anyerror!void {
    @call(.{}, write, .{}); //<- works

    inline for (&[_]u0{}) |a| {
        @call(.{}, write, .{}); //<- works
    }
    inline for (&[_]u0{0}) |a| {
        @call(.{}, write, .{}); //<- works
    }
    inline for (&[_]u0{ 0, 0 }) |a| {
        @call(.{}, write, .{}); //<- cannot asssign to constant
    }

    comptime var i: i64 = 0;
    inline while (i < 0) : (i += 1) {
        @call(.{}, write, .{}); //<- works
    }
    comptime var j: i64 = 0;
    inline while (j < 1) : (j += 1) {
        @call(.{}, write, .{}); //<- works
    }
    comptime var k: i64 = 0;
    inline while (k < 2) : (k += 1) {
        @call(.{}, write, .{}); //<- cannot asssign to constant
    }
}

Expected behaviour: The function call would be inlined (repeated 2 times), and there would be no error.

[joachimschmidt557]

Related to #4639 and #4850

[jwhear]

Just ran into this. It can be worked around by using a simple wrapper function instead of putting the @call directly in the loop:

fn callWrapper(func: anytype, args: anytype) !void {
    try @call(.{}, func, args);
}

[Vexu]

Duplicate of #4639