cmd/compile: do not shapify when reading reshaping expr

Fixes #71184

Change-Id: I22e7ae5203311e86a90502bfe155b0597007887d
Reviewed-on: https://go-review.googlesource.com/c/go/+/641955
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 95054a4f8b6e52aa7b9cb154823f054890889839..c8546198972ad9ee4776f0a3531ca8624971b3f9 100644 (file)
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -49,6 +49,9 @@ type pkgReader struct {
        // but bitwise inverted so we can detect if we're missing the entry
        // or not.
        newindex []index
+
+       // indicates whether the data is reading during reshaping.
+       reshaping bool
 }
 
 func newPkgReader(pr pkgbits.PkgDecoder) *pkgReader {
@@ -116,6 +119,10 @@ type reader struct {
        // find parameters/results.
        funarghack bool
 
+       // reshaping is used during reading exprReshape code, preventing
+       // the reader from shapifying the re-shaped type.
+       reshaping bool
+
        // methodSym is the name of method's name, if reading a method.
        // It's nil if reading a normal function or closure body.
        methodSym *types.Sym
@@ -1007,7 +1014,7 @@ func (pr *pkgReader) objDictIdx(sym *types.Sym, idx index, implicits, explicits
        // arguments.
        for i, targ := range dict.targs {
                basic := r.Bool()
-               if dict.shaped {
+               if dict.shaped && !pr.reshaping {
                        dict.targs[i] = shapify(targ, basic)
                }
        }
@@ -2445,7 +2452,10 @@ func (r *reader) expr() (res ir.Node) {
 
        case exprReshape:
                typ := r.typ()
+               old := r.reshaping
+               r.reshaping = true
                x := r.expr()
+               r.reshaping = old
 
                if types.IdenticalStrict(x.Type(), typ) {
                        return x
@@ -2568,7 +2578,10 @@ func (r *reader) funcInst(pos src.XPos) (wrapperFn, baseFn, dictPtr ir.Node) {
                info := r.dict.subdicts[idx]
                explicits := r.p.typListIdx(info.explicits, r.dict)
 
+               old := r.p.reshaping
+               r.p.reshaping = r.reshaping
                baseFn = r.p.objIdx(info.idx, implicits, explicits, true).(*ir.Name)
+               r.p.reshaping = old
 
                // TODO(mdempsky): Is there a more robust way to get the
                // dictionary pointer type here?

diff --git a/test/fixedbugs/issue71184.go b/test/fixedbugs/issue71184.go
new file mode 100644 (file)
index 0000000..74afc53
--- /dev/null
+++ b/test/fixedbugs/issue71184.go
@@ -0,0 +1,17 @@
+// compile
+
+// Copyright 2024 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 x
+
+func F[T int32]() {
+       _ = G[*[0]T]()[:]
+}
+
+func G[T any]() (v T) {
+       return
+}
+
+var _ = F[int32]