From 8568b9b0795c6b56b5ce481b4879cd5b9dc9a4b5 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Mon, 19 Jul 2021 17:31:13 +0200
Subject: [PATCH] Fix right -> left associativity for assignment.

---
 src/compiler/parse_expr.c                     | 10 +++++++-
 .../expressions/assignment_precedence.c3t     | 23 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 test/test_suite/expressions/assignment_precedence.c3t

diff --git a/src/compiler/parse_expr.c b/src/compiler/parse_expr.c
index 3478902d9..bcd5ac94c 100644
--- a/src/compiler/parse_expr.c
+++ b/src/compiler/parse_expr.c
@@ -391,7 +391,15 @@ static Expr *parse_binary(Context *context, Expr *left_side)
 	}
 	else
 	{
-		right_side = TRY_EXPR_OR(parse_precedence(context, rules[operator_type].precedence + 1), poisoned_expr);
+		// Assignment operators have precedence right -> left.
+		if (rules[operator_type].precedence == PREC_ASSIGNMENT)
+		{
+			right_side = TRY_EXPR_OR(parse_precedence(context, PREC_ASSIGNMENT), poisoned_expr);
+		}
+		else
+		{
+			right_side = TRY_EXPR_OR(parse_precedence(context, rules[operator_type].precedence + 1), poisoned_expr);
+		}
 	}
 
 	Expr *expr = EXPR_NEW_EXPR(EXPR_BINARY, left_side);
diff --git a/test/test_suite/expressions/assignment_precedence.c3t b/test/test_suite/expressions/assignment_precedence.c3t
new file mode 100644
index 000000000..71ab108ff
--- /dev/null
+++ b/test/test_suite/expressions/assignment_precedence.c3t
@@ -0,0 +1,23 @@
+module prec;
+
+func void test()
+{
+    int i = 1;
+    int j = 2;
+    int k = 3;
+    int l = i = j = k;
+}
+
+// #expect: prec.ll
+
+  %i = alloca i32, align 4
+  %j = alloca i32, align 4
+  %k = alloca i32, align 4
+  %l = alloca i32, align 4
+  store i32 1, i32* %i, align 4
+  store i32 2, i32* %j, align 4
+  store i32 3, i32* %k, align 4
+  %0 = load i32, i32* %k, align 4
+  store i32 %0, i32* %j, align 4
+  store i32 %0, i32* %i, align 4
+  store i32 %0, i32* %l, align 4
\ No newline at end of file