dead code elimination

// Test 919: Dead Code Elimination for Optional Branches
//
// This test verifies that the compiler ELIMINATES code paths
// for optional branches that are not handled by any flow.

const std = @import("std");

// Event with optional branches that have complex logic
~event analyze { data: []const u8 }
| success { result: u32 }           // REQUIRED
| ?warning { code: u32, msg: []const u8 }  // OPTIONAL - expensive validation
| ?debug { trace: []const u8 }      // OPTIONAL - detailed logging

~proc analyze {
    const len = data.len;

    // This expensive validation should be ELIMINATED
    // if no flow handles the warning branch
    if (len > 1000) {
        var i: usize = 0;
        var bad_chars: u32 = 0;
        while (i < len) : (i += 1) {
            if (data[i] > 127) {
                bad_chars += 1;
            }
        }
        if (bad_chars > 0) {
            const msg = std.fmt.allocPrint(std.heap.page_allocator,
                "Found {d} non-ASCII chars", .{bad_chars}) catch unreachable;
            return .{ .warning = .{ .code = bad_chars, .msg = msg } };
        }
    }

    // This debug tracing should be ELIMINATED
    // if no flow handles the debug branch
    if (len < 10) {
        const trace = std.fmt.allocPrint(std.heap.page_allocator,
            "Short input: {s}", .{data}) catch unreachable;
        return .{ .debug = .{ .trace = trace } };
    }

    std.debug.print("Analyzed: {d} bytes\n", .{len});
    return .{ .success = .{ .result = @intCast(len) } };
}

// Flow that ONLY handles success
// The warning and debug code paths should be eliminated!
~analyze(data: "hello")
| success |> _