comptime ignored?

comptimeignored.zig

const std = @import("std");

const names_and_vals = [_]struct{name: []const u8, value: u32}{
  .{.name = "first"   , .value = 0x1},
  .{.name = "second"  , .value = 0x2},
  .{.name = "third"   , .value = 0x3},
  };

fn name_to_val(comptime name: []const u8) u32 {
  comptime {
    var return_val: u32 = undefined;
    for(names_and_vals) |tuple, idx| {
      if(std.mem.eql(u8, tuple.name, name)) {
        return_val = tuple.value;
        return return_val;
      }
    } else unreachable;
  }
}

pub fn main() void {
  const val = 0x3;
  std.debug.print("\n -> ", .{});
  switch (val) {
    name_to_val("first") => {
      std.debug.print("first\n", .{});
      return;
    },
    name_to_val("second")  => {
      std.debug.print("second\n", .{});
      return;
    },
    name_to_val("third") => std.debug.print("third\n", .{}),
    else => {
      std.debug.print("last\n", .{});
      return;
    }
  }
  _ = name_to_val("invalid"); //invalid, but only hits 'unreachable' at runtime
  return;
}