compiler: fix `??=`, `||=` and `&&=` logical assignment semantics

When compiling logical assignment expressions, ensure that the right hand
side of the assignment is not evaluated when the assignment condition is
unfulfilled.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 30 insertions, 0 deletions

diff --git a/tests/custom/00_syntax/25_and_or_assignment b/tests/custom/00_syntax/25_and_or_assignment
index 4dbc5f3..d6a9415 100644
--- a/tests/custom/00_syntax/25_and_or_assignment
+++ b/tests/custom/00_syntax/25_and_or_assignment
@@ -53,3 +53,33 @@ expression result if the lhs is falsy.
 	printf("%.J\n", [ x, y, z ]);
 %}
 -- End --
+
+
+3. Ensure that the assignment value expression is not evaluated if the
+assignment condition is false.
+
+-- Expect stdout --
+[
+	0,
+	0,
+	0
+]
+-- End --
+
+-- Testcase --
+{%
+	a = 0;
+	b = 0;
+	c = 0;
+
+	x = false;
+	y = false;
+	z = true;
+
+	x ??= a++;
+	y &&= b++;
+	z ||= c++;
+
+	printf("%.J\n", [ a, b, c ]);
+%}
+-- End --