From 849770dec9191475ffed23f0d0985d8222c51e53 Mon Sep 17 00:00:00 2001 From: Cherry Mui Date: Tue, 14 May 2024 22:34:58 -0400 Subject: [PATCH] cmd/compile: disallow linkname referring to instantiations Linknaming an instantiated generic symbol isn't particularly useful: it doesn't guarantee the instantiation exists, and the instantiated symbol name may be subject to change. Checked with a large code corpus, currently there is no occurrance of linkname to an instantiated generic symbol (or symbol with a bracket in its name). This also suggests that it is not very useful. Linkname is already an unsafe mechanism. We don't need to allow it to do more unsafe things without justification. Change-Id: Ifaa20c98166b28a9d7dc3290c013c2b5bb7682e7 Reviewed-on: https://go-review.googlesource.com/c/go/+/585458 LUCI-TryBot-Result: Go LUCI Reviewed-by: Than McIntosh --- src/cmd/compile/internal/noder/writer.go | 5 +++++ test/linkname3.go | 6 +++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go index a48e193c5f..13706f9dd2 100644 --- a/src/cmd/compile/internal/noder/writer.go +++ b/src/cmd/compile/internal/noder/writer.go @@ -12,6 +12,7 @@ import ( "internal/buildcfg" "internal/pkgbits" "os" + "strings" "cmd/compile/internal/base" "cmd/compile/internal/ir" @@ -2610,6 +2611,10 @@ func (pw *pkgWriter) collectDecls(noders []*noder) { pw.errorf(l.pos, "//go:linkname only allowed in Go files that import \"unsafe\"") continue } + if strings.Contains(l.remote, "[") && strings.Contains(l.remote, "]") { + pw.errorf(l.pos, "//go:linkname reference of an instantiation is not allowed") + continue + } switch obj := pw.curpkg.Scope().Lookup(l.local).(type) { case *types2.Func, *types2.Var: diff --git a/test/linkname3.go b/test/linkname3.go index df110cd064..0d5df0b86e 100644 --- a/test/linkname3.go +++ b/test/linkname3.go @@ -13,13 +13,17 @@ type t int var x, y int +func F[T any](T) {} + //go:linkname x ok // ERROR "//go:linkname must refer to declared function or variable" // ERROR "//go:linkname must refer to declared function or variable" // ERROR "duplicate //go:linkname for x" +// ERROR "//go:linkname reference of an instantiation is not allowed" -//line linkname3.go:18 +//line linkname3.go:20 //go:linkname nonexist nonexist //go:linkname t notvarfunc //go:linkname x duplicate +//go:linkname i F[go.shape.int]