source: tests/eval.cfa@ a55ebcc

//
// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// eval.cfa -- tests of static expression evaluation inside cfacc
//
// Author           : Michael Brooks
// Created On       : Tue Jun 13 15:00:00 2023
// Last Modified By : Michael Brooks
// Last Modified On : Tue Jun 13 15:00:00 2023
// Update Count     : 1
//

// Tests that target specific cases of `eval`, of Common/Eval.h.
// So logically unit tests, but driven inderctly though the usual rig.

#ifndef __cforall
int printf(const char *, ...);
#endif

// A bug found and fixed with eval of sizeof.
// Driving it through the black-box rig was a matter of reverse engineering.
// Seen failing on rev 576aad.
// White-box relevance:
// - Initializer of `a`, which is `{1, 2, 3}` checks its element expressions
//   (e.g. `2`) against the type being initialized (`int[bar]`) to see if a
//   `2` makes sense here.
// - Understanding this type evaluates the index expression `bar`, whose
//   value comes from a sizeof expression.  General sizeof expressions are
//   unknown to cfacc, because C's implementation-specific rules affect
//   struct layout.
// - When the bug was observed, this evaluation was returning "known to be 0".
//   If the array's size were zero, the intializer would be invalid.  So a
//   buggy cfacc rejects this program.
// GCC accepts this program.
void test_sizeof_1() {
    struct foo { int x; };
    enum { bar = sizeof(struct foo) };
    int a[bar] = {1, 2, 3};
}

int main() {
    test_sizeof_1();
    printf("Done\n");
}