harec

commit c77ca2f0b265f4421cacedd6b10fce3e6adb8515
parent ba423ce6f0a2692e2105645b05b2beb09c061c28
Author: Eyal Sawady <ecs@d2evs.net>
Date:   Wed, 11 Aug 2021 07:19:41 +0000

gen: fix nested match with aliases

In this case:

type t = (void | int);
fn foo() void = {
	let x: (t | int) = 10;
	match (x) {
		(void | int) => void,
		int => void,
	};
};

we wouldn't exit the loop on test == t because it doesn't have the same
id as (void | int). Rather than just testing against t, test against
type_dealias(t) as well.

We don't want to dealias _case->type, because that can lead to false
positives. For example, in this case:

type foo = void;
type bar = void;
fn foo() void = {
	match (foo) {
		bar => void,
		foo => void,
	};
};

we need to avoid matching with bar.

This issue was causing 18-match to fail, now that it's fixed, enable
that test.

Signed-off-by: Eyal Sawady <ecs@d2evs.net>

Diffstat:
M
src/gen.c
 | 
6
++++--
M
tests/configure
 | 
2
+-

2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/src/gen.c b/src/gen.c
@@ -1638,7 +1638,8 @@ gen_nested_match_tests(struct gen_context *ctx, struct gen_value object,
 		pushi(ctx->current, NULL, Q_JNZ, &match, &bsubtype, &bnext, NULL);
 		push(&ctx->current->body, &lsubtype);
 
-		if (test->id != _case->type->id) {
+		if (test->id != _case->type->id
+				&& type_dealias(test)-> id != _case->type->id) {
 			struct qbe_value offs = constl(subtype->align);
 			pushi(ctx->current, &subval, Q_ADD, &subval, &offs, NULL);
 			pushi(ctx->current, &temp, Q_LOADUW, &subval, NULL);
@@ -1647,7 +1648,8 @@ gen_nested_match_tests(struct gen_context *ctx, struct gen_value object,
 		}
 
 		subtype = test;
-	} while (test->id != _case->type->id);
+	} while (test->id != _case->type->id
+		&& type_dealias(test)->id != _case->type->id);
 
 	pushi(ctx->current, NULL, Q_JMP, &bmatch, NULL);
 }
diff --git a/tests/configure b/tests/configure
@@ -57,6 +57,7 @@ EOF
 		15-enums \
 		16-defer \
 		17-alloc \
+		18-match \
 		19-append \
 		20-if \
 		24-imports \
@@ -66,7 +67,6 @@ EOF
 		29-unarithm
 
 	# Disabled tests
-		#18-match \
 		#21-tuples \
 		#22-delete \
 		#23-errors \