From dcc8350ad304714824cc8e5b8a00105dabb61c54 Mon Sep 17 00:00:00 2001 From: Dan Scales Date: Sun, 18 Jul 2021 22:10:13 -0700 Subject: [PATCH] [dev.typeparams] cmd/compile: handle ++/-- in noder2 for operands with generic type types2 will have already proved the expression's type is compatible, so just assign the one const to have the same type as the operand. Fixes #47258. Change-Id: If0844e6bf6d0a5e6b11453b87df71353863ccc5d Reviewed-on: https://go-review.googlesource.com/c/go/+/336009 Run-TryBot: Dan Scales TryBot-Result: Go Bot Reviewed-by: Keith Randall Trust: Dan Scales --- src/cmd/compile/internal/noder/helpers.go | 12 ++++++++- test/typeparam/issue47258.go | 32 +++++++++++++++++++++++ 2 files changed, 43 insertions(+), 1 deletion(-) create mode 100644 test/typeparam/issue47258.go diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go index 7da5aa3102..15b3277908 100644 --- a/src/cmd/compile/internal/noder/helpers.go +++ b/src/cmd/compile/internal/noder/helpers.go @@ -337,5 +337,15 @@ var one = constant.MakeInt64(1) func IncDec(pos src.XPos, op ir.Op, x ir.Node) *ir.AssignOpStmt { assert(x.Type() != nil) - return ir.NewAssignOpStmt(pos, op, x, typecheck.DefaultLit(ir.NewBasicLit(pos, one), x.Type())) + bl := ir.NewBasicLit(pos, one) + if x.Type().HasTParam() { + // If the operand is generic, then types2 will have proved it must be + // a type that fits with increment/decrement, so just set the type of + // "one" to n.Type(). This works even for types that are eventually + // float or complex. + typed(x.Type(), bl) + } else { + bl = typecheck.DefaultLit(bl, x.Type()) + } + return ir.NewAssignOpStmt(pos, op, x, bl) } diff --git a/test/typeparam/issue47258.go b/test/typeparam/issue47258.go new file mode 100644 index 0000000000..76629f7424 --- /dev/null +++ b/test/typeparam/issue47258.go @@ -0,0 +1,32 @@ +// 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 + +import ( + "fmt" +) + +type Numeric interface { + int32|int64|float64|complex64 +} + +//go:noline +func inc[T Numeric](x T) T { + x++ + return x +} +func main() { + if got, want := inc(int32(5)), int32(6); got != want { + panic(fmt.Sprintf("got %d, want %d", got, want)) + } + if got, want := inc(float64(5)), float64(6.0); got != want { + panic(fmt.Sprintf("got %d, want %d", got, want)) + } + if got, want := inc(complex64(5)), complex64(6.0); got != want { + panic(fmt.Sprintf("got %d, want %d", got, want)) + } +}