interp: fix switch expression (traefik#1370)

The control flow graph was incorrect for the initial clause. Fixes traefik#1368.
hswuhao · Apr 6, 2022 · 371103f · 371103f
1 parent 8bd7afb
commit 371103f
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diff --git a/_test/issue-1368.go b/_test/issue-1368.go
@@ -0,0 +1,16 @@
+package main
+
+const dollar byte = 36
+
+func main() {
+	var c byte = 36
+	switch true {
+	case c == dollar:
+		println("ok")
+	default:
+		println("not ok")
+	}
+}
+
+// Output:
+// ok
diff --git a/interp/cfg.go b/interp/cfg.go
@@ -1832,6 +1832,7 @@ func (interp *Interpreter) cfg(root *node, sc *scope, importPath, pkgName string
 					setFNext(c, clauses[i+1])
 				}
 			}
+			sbn.start = clauses[0].start
 			n.start = n.child[0].start
 			n.child[0].tnext = sbn.start