stage2 self referential array memory corruption #13415
Description
Zig Version
0.11.0-dev.18+81c27677d
Steps to Reproduce and Observed Behavior
const std = @import("std");
var i: u8 = 3;
fn bar(a: u8, b: u8, c: []u8) u8 {
var j: u8 = 0;
while (j < b) : (j += 1) {
c[j] = a + j;
}
return a;
}
pub fn main() !void {
var foo: [10]u8 = undefined;
const baz = foo[bar(i, 6, &foo)];
const qux = foo[bar(i, 9, &foo)];
std.debug.print("{d} {d}\n", .{ baz, qux });
// workaround - behaves as expected
var arr: [10]u8 = undefined;
const a = bar(i, 6, &arr);
const b = arr[a];
const c = bar(i, 9, &arr);
const d = arr[c];
std.debug.print("{d} {d}\n", .{ b, d });
}$ zig run main.zig
170 6
6 6
possibly eagerly reading from undefined memory?
Expected Behavior
This worked with stage 1:
$ zig run -fstage1 main.zig
6 6
6 6
and alternatively works in C:
#include <stdio.h>
int bar(int a, int b, int c[10]) {
for (int j = 0; j < b; j++) {
c[j] = a + j;
}
return a;
}
int main() {
int i = 3;
int foo[10];
int baz = foo[bar(i, 6, &foo)];
int qux = foo[bar(i, 9, &foo)];
printf("%d %d\n", baz, qux);
int arr[10];
int a = bar(i, 6, &arr);
int b = arr[a];
int c = bar(i, 9, &arr);
int d = arr[c];
printf("%d %d\n", b, d);
return 0;
}$ zig cc main.c && ./a.out
6 6
6 6