radiance · commit

Resolve coerced throw types

5579ed175341f1c57cabd28ce6dbad6c4a1908820bcd4487e9673581d336f70a

Throw resolution recorded the error tag from the expression's
pre-coercion type. Throwing an unsuffixed integer from a `throws(u8)`
function therefore emitted the tag for `Int` while typed `u8` catch
dispatch expected the `u8` tag and missed the handler.

Select the throw's resolved coerced type when registering and lowering
its error payload, while retaining the original type when no coercion
exists.

Alexis Sellier committed 23 days ago 1 parent c08a46ca

lib/std/lang/lower.rad +2 -1


/// Lower a throw statement.
fn lowerThrowStmt(self: *mut FnLowerer, expr: *ast::Node) throws (LowerError) {
    assert self.fnType.throwList.len > 0;

    let errType = try typeOf(self, expr);
    let errType = *self.fnType.throwList[0] if self.fnType.throwList.len == 1
        else try typeOf(self, expr);
    let tag = getOrAssignErrorTag(self.low, errType) as i64;
    let errVal = try lowerExpr(self, expr);
    let resultVal = try buildResult(self, tag, errVal, errType);

    try emitRetVal(self, resultVal);

test/tests/error.throw.coercion.rad added +16 -0

1	+	//! returns: 0
2	+	//! A coerced error value must use the declared error type's dispatch tag.
3	+
4	+	fn fail() throws (u8) {
5	+	throw 7;
6	+	}
7	+
8	+	@default fn main() -> i32 {
9	+	let mut caught = false;
10	+	try fail() catch value as u8 {
11	+	assert value == 7;
12	+	set caught = true;
13	+	};
14	+	assert caught;
15	+	return 0;
16	+	}

5683	5683
5684	5684		/// Lower a throw statement.
5685	5685		fn lowerThrowStmt(self: mut FnLowerer, expr: ast::Node) throws (LowerError) {
5686	5686		assert self.fnType.throwList.len > 0;
5687	5687
5688		-	let errType = try typeOf(self, expr);
	5688	+	let errType = *self.fnType.throwList[0] if self.fnType.throwList.len == 1
	5689	+	else try typeOf(self, expr);
5689	5690		let tag = getOrAssignErrorTag(self.low, errType) as i64;
5690	5691		let errVal = try lowerExpr(self, expr);
5691	5692		let resultVal = try buildResult(self, tag, errVal, errType);
5692	5693
5693	5694		try emitRetVal(self, resultVal);