From be571a36c7aa7198aef4712f8c6cde633e2f380b Mon Sep 17 00:00:00 2001 From: Leonard Wang Date: Thu, 7 Oct 2021 20:14:22 +0800 Subject: [PATCH] cmd/compile: fix the index variable is shadowed in dictPass The CL 349613 causes this problem. In fact, we want to use the outer i to find m.List[i], but the newly created index variable i in the nearest for range shadow the outer i. Fixes #48838. Change-Id: I10f0bd985340f9443eefaadda6fc56e4e7e9a10c Reviewed-on: https://go-review.googlesource.com/c/go/+/354549 Run-TryBot: Cuong Manh Le TryBot-Result: Go Bot Reviewed-by: Keith Randall Reviewed-by: Dan Scales Trust: Dan Scales --- src/cmd/compile/internal/noder/stencil.go | 4 +-- test/typeparam/issue48838.go | 31 +++++++++++++++++++++++ 2 files changed, 33 insertions(+), 2 deletions(-) create mode 100644 test/typeparam/issue48838.go diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go index 2bc1756b8d..62d6a45819 100644 --- a/src/cmd/compile/internal/noder/stencil.go +++ b/src/cmd/compile/internal/noder/stencil.go @@ -1298,9 +1298,9 @@ func (g *irgen) dictPass(info *instInfo) { // Type switch from nonempty interface. We need a *runtime.itab // for the dynamic type. ix := -1 - for i, ic := range info.dictInfo.itabConvs { + for j, ic := range info.dictInfo.itabConvs { if ic == m.List[i] { - ix = info.dictInfo.startItabConv + i + ix = info.dictInfo.startItabConv + j break } } diff --git a/test/typeparam/issue48838.go b/test/typeparam/issue48838.go new file mode 100644 index 0000000000..ef2150d6a2 --- /dev/null +++ b/test/typeparam/issue48838.go @@ -0,0 +1,31 @@ +// run -gcflags=-G=3 + +// Copyright 2021 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package main + +func main() { + check[string]() +} + +func check[T any]() { + var result setter[T] + switch result.(type) { + case fooA[T]: + case fooB[T]: + } +} + +type setter[T any] interface { + Set(T) +} + +type fooA[T any] struct{} + +func (fooA[T]) Set(T) {} + +type fooB[T any] struct{} + +func (fooB[T]) Set(T) {} -- 2.50.0