From 05104eea01b775a8738a8ddef7e5d3168fbbbdd0 Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Tue, 30 Jul 2024 19:54:04 +0200
Subject: [PATCH] interp: fix a missing implicit type conversion for binary
 expression

When parsing binary operator expressions, make sure that implicit type conversions for untyped expressions are performed. It involves walking the sub-expression subtree at post-processing of binary expressions.

Fixes #1653.
---
 _test/issue-1653.go | 12 ++++++++++++
 interp/cfg.go       | 17 +++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 _test/issue-1653.go

diff --git a/_test/issue-1653.go b/_test/issue-1653.go
new file mode 100644
index 00000000..8986d1f6
--- /dev/null
+++ b/_test/issue-1653.go
@@ -0,0 +1,12 @@
+package main
+
+func f(b uint) uint {
+	return uint(1) + (0x1 >> b)
+}
+
+func main() {
+	println(f(1))
+}
+
+// Output:
+// 1
diff --git a/interp/cfg.go b/interp/cfg.go
index ce9f6a9c..e5eae1ff 100644
--- a/interp/cfg.go
+++ b/interp/cfg.go
@@ -982,6 +982,9 @@ func (interp *Interpreter) cfg(root *node, sc *scope, importPath, pkgName string
 				// Allocate a new location in frame, and store the result here.
 				n.findex = sc.add(n.typ)
 			}
+			if n.typ != nil && !n.typ.untyped {
+				fixUntyped(n, sc)
+			}
 
 		case indexExpr:
 			if isBlank(n.child[0]) {
@@ -2300,6 +2303,20 @@ func (interp *Interpreter) cfg(root *node, sc *scope, importPath, pkgName string
 	return initNodes, err
 }
 
+// fixUntyped propagates implicit type conversions for untyped binary expressions.
+func fixUntyped(nod *node, sc *scope) {
+	nod.Walk(func(n *node) bool {
+		if n == nod || (n.kind != binaryExpr && n.kind != parenExpr) || !n.typ.untyped {
+			return true
+		}
+		n.typ = nod.typ
+		if n.findex >= 0 {
+			sc.types[n.findex] = nod.typ.frameType()
+		}
+		return true
+	}, nil)
+}
+
 func compDefineX(sc *scope, n *node) error {
 	l := len(n.child) - 1
 	types := []*itype{}