Python3-Win9x/scripts/fixtures/vc6_decl_order_smoke.c

/* Focused compile smoke test for the VC6 C89-mixed-declarations fixes
 * applied to cpython/Modules/main.c.
 *
 * VC6 is a C89-only compiler (plus Microsoft extensions): block-scope
 * declarations must precede all statements in that block. Modules/main.c
 * declared many locals mid-function (typically right before first use,
 * C99 style); the fix hoists each declaration to the top of its enclosing
 * block, without initializer, and turns the original `TYPE name = expr;`
 * into a plain `name = expr;` assignment at its original position. This
 * changes no evaluation order and no semantics. See PORT_STATUS.md
 * ("Modules/main.c mixed-declarations slice") for full detail.
 *
 * This fixture is deliberately self-contained (no CPython headers) so it
 * exercises the *shape* of every hoist pattern used in main.c, independent
 * of main.c's own evolution:
 *
 *   1. a bare declaration hoisted above an early-return statement
 *      (pymain_init's `preconfig`/`config`);
 *   2. a declaration whose initializer is a side-effecting call, hoisted
 *      bare and assigned at its original site so the call itself still
 *      happens after the same preceding statements
 *      (pymain_import_readline's `mod`, pymain_run_file_obj's `fp`);
 *   3. two declarations in a row where hoisting the first turns its site
 *      into an assignment statement, which would otherwise make the
 *      second declaration (immediately following) a new violation too
 *      (pymain_run_file_obj's `cf`/`run`);
 *   4. a declaration inside a nested block (its own scope), after
 *      statements already executed in that block (pymain_run_stdin's
 *      nested `exitcode`);
 *   5. a platform-conditional declaration with the same name but a
 *      different type per branch, hoisted under the same #ifdef structure
 *      at the top of the function (pymain_run_startup's `env`).
 */

#define TARGET_WINDOWS 1

/* --- pattern 1: bare declaration hoisted above an early return --- */
static int
decl_after_early_return(int flag)
{
    int status;
    int extra;

    status = flag ? 0 : -1;
    if (status != 0) {
        return status;
    }

    extra = 7;
    return extra;
}

/* --- pattern 2: side-effecting-initializer declaration hoisted bare,
 * assigned at its original position so the call still happens after the
 * same preceding statements --- */
static int
side_effect(int *counter)
{
    (*counter)++;
    return *counter;
}

static int
decl_with_side_effecting_init(int *counter)
{
    int guard;
    int value;

    guard = (*counter < 0);
    if (guard) {
        return -1;
    }

    value = side_effect(counter);
    return value;
}

/* --- pattern 3: two declarations in a row, first one hoisted becomes an
 * assignment, so the second (immediately following) must hoist too --- */
static int
decl_pair_after_hoist(int *counter)
{
    int guard;
    int a;
    int b;

    guard = (*counter < 0);
    if (guard) {
        return -1;
    }

    a = side_effect(counter);
    b = side_effect(counter);
    return a + b;
}

/* --- pattern 4: nested-block declaration after statements already
 * executed within that same nested block --- */
static int
decl_after_statement_in_nested_block(int interactive)
{
    int outer_result = 0;

    if (interactive) {
        int inner_value;

        outer_result += 1;
        outer_result += 2;

        inner_value = outer_result * 10;
        return inner_value;
    }

    return outer_result;
}

/* --- pattern 5: platform-conditional declaration, same name, different
 * type per branch, hoisted under the same #ifdef at the top --- */
static long
decl_platform_conditional(void)
{
    int ret;
#ifdef TARGET_WINDOWS
    const char *env;
#else
    const long *env;
#endif

    ret = 1;
    if (!ret) {
        return 0;
    }

#ifdef TARGET_WINDOWS
    env = "PYTHONSTARTUP";
    if (env == 0) {
        return 0;
    }
    return (long)env[0];
#else
    env = 0;
    if (env == 0) {
        return 0;
    }
    return *env;
#endif
}

int
main(void)
{
    int counter = 0;
    int total = 0;

    total += decl_after_early_return(1);
    total += decl_with_side_effecting_init(&counter);
    total += decl_pair_after_hoist(&counter);
    total += decl_after_statement_in_nested_block(1);
    total += (int)decl_platform_conditional();

    return (total >= 0) ? 0 : 1;
}