From c048a9a11f21e879a76e328b7a92f3a47f298b37 Mon Sep 17 00:00:00 2001
From: Mark Freeman <mark@golang.org>
Date: Tue, 25 Nov 2025 13:56:18 -0500
Subject: [PATCH] go/types, types2: remove InvalidTypeCycle from literals.go

Both CL 722161 and CL 724140 implement a more general solution to
detecting cycles involving values of a type on the object path.

The logic in literals.go was intended to be a stop-gap solution and
is no longer necessary.

Change-Id: I328c0febf35444f07fc1894278dc76ab140710bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/724380
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Mark Freeman <markfreeman@google.com>
---
 src/cmd/compile/internal/types2/literals.go | 29 ---------------------
 src/go/types/literals.go                    | 29 ---------------------
 2 files changed, 58 deletions(-)

diff --git a/src/cmd/compile/internal/types2/literals.go b/src/cmd/compile/internal/types2/literals.go
index 5b2dae9b13a..ed1c3f695c8 100644
--- a/src/cmd/compile/internal/types2/literals.go
+++ b/src/cmd/compile/internal/types2/literals.go
@@ -145,13 +145,6 @@ func (check *Checker) compositeLit(x *operand, e *syntax.CompositeLit, hint Type
 
 	switch u, _ := commonUnder(base, nil); utyp := u.(type) {
 	case *Struct:
-		// Prevent crash if the struct referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.fields == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		if len(e.ElemList) == 0 {
 			break
 		}
@@ -225,14 +218,6 @@ func (check *Checker) compositeLit(x *operand, e *syntax.CompositeLit, hint Type
 		}
 
 	case *Array:
-		// Prevent crash if the array referred to is not yet set up. Was go.dev/issue/18643.
-		// This is a stop-gap solution. Should use Checker.objPath to report entire
-		// path starting with earliest declaration in the source. TODO(gri) fix this.
-		if utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		n := check.indexedElts(e.ElemList, utyp.elem, utyp.len)
 		// If we have an array of unknown length (usually [...]T arrays, but also
 		// arrays [n]T where n is invalid) set the length now that we know it and
@@ -254,23 +239,9 @@ func (check *Checker) compositeLit(x *operand, e *syntax.CompositeLit, hint Type
 		}
 
 	case *Slice:
-		// Prevent crash if the slice referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		check.indexedElts(e.ElemList, utyp.elem, -1)
 
 	case *Map:
-		// Prevent crash if the map referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.key == nil || utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		// If the map key type is an interface (but not a type parameter),
 		// the type of a constant key must be considered when checking for
 		// duplicates.
diff --git a/src/go/types/literals.go b/src/go/types/literals.go
index df02b770364..7ca351e60b1 100644
--- a/src/go/types/literals.go
+++ b/src/go/types/literals.go
@@ -149,13 +149,6 @@ func (check *Checker) compositeLit(x *operand, e *ast.CompositeLit, hint Type) {
 
 	switch u, _ := commonUnder(base, nil); utyp := u.(type) {
 	case *Struct:
-		// Prevent crash if the struct referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.fields == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		if len(e.Elts) == 0 {
 			break
 		}
@@ -229,14 +222,6 @@ func (check *Checker) compositeLit(x *operand, e *ast.CompositeLit, hint Type) {
 		}
 
 	case *Array:
-		// Prevent crash if the array referred to is not yet set up. Was go.dev/issue/18643.
-		// This is a stop-gap solution. Should use Checker.objPath to report entire
-		// path starting with earliest declaration in the source. TODO(gri) fix this.
-		if utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		n := check.indexedElts(e.Elts, utyp.elem, utyp.len)
 		// If we have an array of unknown length (usually [...]T arrays, but also
 		// arrays [n]T where n is invalid) set the length now that we know it and
@@ -258,23 +243,9 @@ func (check *Checker) compositeLit(x *operand, e *ast.CompositeLit, hint Type) {
 		}
 
 	case *Slice:
-		// Prevent crash if the slice referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		check.indexedElts(e.Elts, utyp.elem, -1)
 
 	case *Map:
-		// Prevent crash if the map referred to is not yet set up.
-		// See analogous comment for *Array.
-		if utyp.key == nil || utyp.elem == nil {
-			check.error(e, InvalidTypeCycle, "invalid recursive type")
-			x.mode = invalid
-			return
-		}
 		// If the map key type is an interface (but not a type parameter),
 		// the type of a constant key must be considered when checking for
 		// duplicates.