From: Robert Griesemer <gri@golang.org>
Date: Thu, 20 Oct 2022 22:56:11 +0000 (-0700)
Subject: cmd/compile: add support for alternative comparable semantics
X-Git-Tag: go1.20rc1~537
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b95ea201d54953055e7d5d29cf68bb5f19f21f93;p=gostls13.git

cmd/compile: add support for alternative comparable semantics

Add the experimental compiler flag -altcomparable. If set, the
compiler uses alternative comparable semantics: any ordinary
(non-type parameter) interface implements the comparable
constraint.

This permits experimenting with this alternative semantics
akin to what is proposed in #52509.

For #52509.

Change-Id: I64192eee6f2a550eeb50de011079f2f0b994cf94
Reviewed-on: https://go-review.googlesource.com/c/go/+/444636
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
---

diff --git a/src/cmd/compile/internal/base/flag.go b/src/cmd/compile/internal/base/flag.go
index 42273ea350..3e9d86c9bc 100644
--- a/src/cmd/compile/internal/base/flag.go
+++ b/src/cmd/compile/internal/base/flag.go
@@ -122,7 +122,8 @@ type CmdFlags struct {
 	SymABIs            string       "help:\"read symbol ABIs from `file`\""
 	TraceProfile       string       "help:\"write an execution trace to `file`\""
 	TrimPath           string       "help:\"remove `prefix` from recorded source file paths\""
-	WB                 bool         "help:\"enable write barrier\"" // TODO: remove
+	WB                 bool         "help:\"enable write barrier\""                    // TODO: remove
+	AltComparable      bool         "help:\"enable alternative comparable semantics\"" // experiment - remove eventually
 
 	// Configuration derived from flags; not a flag itself.
 	Cfg struct {
diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 57872bce27..4a15c626b9 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -55,8 +55,9 @@ func checkFiles(noders []*noder) (posMap, *types2.Package, *types2.Info) {
 			}
 			base.ErrorfAt(m.makeXPos(terr.Pos), "%s", msg)
 		},
-		Importer: &importer,
-		Sizes:    &gcSizes{},
+		Importer:               &importer,
+		Sizes:                  &gcSizes{},
+		AltComparableSemantics: base.Flag.AltComparable, // experiment - remove eventually
 	}
 	info := &types2.Info{
 		StoreTypesInSyntax: true,