From: Dan Scales <danscales@google.com>
Date: Sun, 18 Jul 2021 18:10:41 +0000 (-0700)
Subject: [dev.typeparams] transformDot() should set Selection and tc flag for added ODOTs
X-Git-Tag: go1.18beta1~1818^2^2~104
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=a2e2b0362bb2e7b93de668007027d08888bc9a38;p=gostls13.git

[dev.typeparams] transformDot() should set Selection and tc flag for added ODOTs

Fixes -G=3 issue with issue44688.go.

Change-Id: Ie98c0cbd48683dedd115332043f14c8f3160f46c
Reviewed-on: https://go-review.googlesource.com/c/go/+/337029
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
---

diff --git a/src/cmd/compile/internal/noder/transform.go b/src/cmd/compile/internal/noder/transform.go
index f89ae13237..2fe55a6852 100644
--- a/src/cmd/compile/internal/noder/transform.go
+++ b/src/cmd/compile/internal/noder/transform.go
@@ -591,6 +591,24 @@ func transformDot(n *ir.SelectorExpr, isCall bool) ir.Node {
 	if n.Op() == ir.OXDOT {
 		n = typecheck.AddImplicitDots(n)
 		n.SetOp(ir.ODOT)
+
+		// Set the Selection field and typecheck flag for any new ODOT nodes
+		// added by AddImplicitDots(), and also transform to ODOTPTR if
+		// needed. Equivalent to 'n.X = typecheck(n.X, ctxExpr|ctxType)' in
+		// tcDot.
+		for n1 := n; n1.X.Op() == ir.ODOT; {
+			n1 = n1.X.(*ir.SelectorExpr)
+			if !n1.Implicit() {
+				break
+			}
+			t1 := n1.X.Type()
+			if t1.IsPtr() && !t1.Elem().IsInterface() {
+				t1 = t1.Elem()
+				n1.SetOp(ir.ODOTPTR)
+			}
+			typecheck.Lookdot(n1, t1, 0)
+			n1.SetTypecheck(1)
+		}
 	}
 
 	t := n.X.Type()
diff --git a/test/run.go b/test/run.go
index 5624654fec..1e7fab4359 100644
--- a/test/run.go
+++ b/test/run.go
@@ -2185,8 +2185,7 @@ var g3Failures = setOf(
 	"typeparam/mdempsky/4.go",  // -G=3 can't export functions with labeled breaks in loops
 	"typeparam/mdempsky/13.go", // problem with interface as as a type arg.
 
-	"typeparam/cons.go",       // causes an unreachable method
-	"typeparam/issue44688.go", // interface conversion fails due to missing method
+	"typeparam/cons.go", // causes an unreachable method
 )
 
 var unifiedFailures = setOf(