harec

commit e2b6d35ded1f3dd0cb8657553950f373c2734c6b
parent dd50ca7740408e3c6e41c0ca48b59b9f7f5911f2
Author: Lassi Pulkkinen <lassi@pulk.fi>
Date:   Thu, 16 Mar 2023 16:18:15 +0200

Don't use gen_expr_at for assignments

This caused the assignment to be partially observable from the rhs
expression if it contained a reference to the destination, e.g.

let x = (1, 0);
x = (2, x.0);
fmt::println(x.1)!;

prints "2" when it should print "1".

Signed-off-by: Lassi Pulkkinen <lassi@pulk.fi>

Diffstat:
M
src/gen.c
 | 
2
+-
M
tests/01-arrays.ha
 | 
3
+++
M
tests/21-tuples.ha
 | 
4
++++

3 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/gen.c b/src/gen.c
@@ -916,7 +916,7 @@ gen_expr_assign(struct gen_context *ctx, const struct expression *expr)
 		abort(); // Invariant
 	}
 	if (expr->assign.op == BIN_LEQUAL) {
-		gen_expr_at(ctx, value, obj);
+		gen_store(ctx, obj, gen_expr(ctx, value));
 	} else if (expr->assign.op == BIN_LAND || expr->assign.op == BIN_LOR) {
 		struct qbe_statement lrval, lshort;
 		struct qbe_value brval = mklabel(ctx, &lrval, ".%d");
diff --git a/tests/01-arrays.ha b/tests/01-arrays.ha
@@ -60,8 +60,11 @@ fn assignment() void = {
 	let y = x;
 	let z = [0, 0, 0];
 	z = y;
+	let w = [1, 0];
+	w = [2, w[0]];
 	assert(y[0] == 1 && y[1] == 2 && y[2] == 3);
 	assert(z[0] == 1 && z[1] == 2 && z[2] == 3);
+	assert(w[0] == 2 && w[1] == 1);
 
 	assert(compile("
 		export fn main() void = {
diff --git a/tests/21-tuples.ha b/tests/21-tuples.ha
@@ -122,6 +122,10 @@ fn unpacking() void = {
 // Regression tests for miscellaneous compiler bugs
 fn regression() void = {
 	let a: (((int | void), int) | void) = (void, 0);
+
+	let x = (1, 0);
+	x = (2, x.0);
+	assert(x.0 == 2 && x.1 == 1);
 };
 
 fn reject() void = {