go/types, types2: simplify cycle reporting code (minor cleanup)

Change-Id: I49c7107d9624c9a8aa97dcc87e2d4722b9ba0a20
Reviewed-on: https://go-review.googlesource.com/c/go/+/622055
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Tim King <taking@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>

diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index b8e43231a15d31f48e6d60e7e13581fff3fe58e4..517a3d3def8f79bec1e27f73dadfe86eeff14148 100644 (file)
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -306,9 +306,8 @@ func (check *Checker) cycleError(cycle []Object, start int) {
                return packagePrefix(obj.Pkg(), check.qualifier) + obj.Name()
        }
 
-       obj := cycle[start]
-       objName := name(obj)
        // If obj is a type alias, mark it as valid (not broken) in order to avoid follow-on errors.
+       obj := cycle[start]
        tname, _ := obj.(*TypeName)
        if tname != nil && tname.IsAlias() {
                // If we use Alias nodes, it is initialized with Typ[Invalid].
@@ -321,26 +320,24 @@ func (check *Checker) cycleError(cycle []Object, start int) {
        // report a more concise error for self references
        if len(cycle) == 1 {
                if tname != nil {
-                       check.errorf(obj, InvalidDeclCycle, "invalid recursive type: %s refers to itself", objName)
+                       check.errorf(obj, InvalidDeclCycle, "invalid recursive type: %s refers to itself", name(obj))
                } else {
-                       check.errorf(obj, InvalidDeclCycle, "invalid cycle in declaration: %s refers to itself", objName)
+                       check.errorf(obj, InvalidDeclCycle, "invalid cycle in declaration: %s refers to itself", name(obj))
                }
                return
        }
 
        err := check.newError(InvalidDeclCycle)
        if tname != nil {
-               err.addf(obj, "invalid recursive type %s", objName)
+               err.addf(obj, "invalid recursive type %s", name(obj))
        } else {
-               err.addf(obj, "invalid cycle in declaration of %s", objName)
-       }
-       // "cycle[i] refers to cycle[j]" for (i,j) = (s, s+1), (s+1, s+2), ..., (n, 0), (0,1), ..., (s-1,s) for len(cycle) = n, s = start.
-       n := len(cycle)
-       rotate := func(i int) int { return (i + start) % n }
-       for i := range n {
-               obj := cycle[rotate(i)]
-               next := cycle[rotate(i+1)]
+               err.addf(obj, "invalid cycle in declaration of %s", name(obj))
+       }
+       // "cycle[i] refers to cycle[j]" for (i,j) = (s,s+1), (s+1,s+2), ..., (n-1,0), (0,1), ..., (s-1,s) for len(cycle) = n, s = start.
+       for i := range cycle {
+               next := cycle[(start+i+1)%len(cycle)]
                err.addf(obj, "%s refers to %s", name(obj), name(next))
+               obj = next
        }
        err.report()
 }

diff --git a/src/cmd/compile/internal/types2/initorder.go b/src/cmd/compile/internal/types2/initorder.go
index 9efbf7f69f8581bc34f2587d27ef43c76b7eafed..ef2ad010a6d5fb80bc0bff2a6686f05a69226f6a 100644 (file)
--- a/src/cmd/compile/internal/types2/initorder.go
+++ b/src/cmd/compile/internal/types2/initorder.go
@@ -163,10 +163,11 @@ func (check *Checker) reportCycle(cycle []Object) {
 
        err := check.newError(InvalidInitCycle)
        err.addf(obj, "initialization cycle for %s", obj.Name())
-       // "cycle[i] refers to cycle[j]" for (i,j) = (0, n-1), (n-1, n-2), ..., (1,0) for len(cycle) = n.
+       // "cycle[i] refers to cycle[j]" for (i,j) = (0,n-1), (n-1,n-2), ..., (1,0) for len(cycle) = n.
        for j := len(cycle) - 1; j >= 0; j-- {
-               err.addf(obj, "%s refers to %s", obj.Name(), cycle[j].Name())
-               obj = cycle[j]
+               next := cycle[j]
+               err.addf(obj, "%s refers to %s", obj.Name(), next.Name())
+               obj = next
        }
        err.report()
 }

diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index 498eb16f8488291a8c27576a1e15700d4849dcd1..04dfc5af4b3720fcb2af7b9a56a89c6a4a30928d 100644 (file)
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -302,14 +302,13 @@ func (check *Checker) cycleError(cycle []Object, start int) {
        // name returns the (possibly qualified) object name.
        // This is needed because with generic types, cycles
        // may refer to imported types. See go.dev/issue/50788.
-       // TODO(gri) Thus functionality is used elsewhere. Factor it out.
+       // TODO(gri) This functionality is used elsewhere. Factor it out.
        name := func(obj Object) string {
                return packagePrefix(obj.Pkg(), check.qualifier) + obj.Name()
        }
 
-       obj := cycle[start]
-       objName := name(obj)
        // If obj is a type alias, mark it as valid (not broken) in order to avoid follow-on errors.
+       obj := cycle[start]
        tname, _ := obj.(*TypeName)
        if tname != nil && tname.IsAlias() {
                // If we use Alias nodes, it is initialized with Typ[Invalid].
@@ -322,27 +321,24 @@ func (check *Checker) cycleError(cycle []Object, start int) {
        // report a more concise error for self references
        if len(cycle) == 1 {
                if tname != nil {
-                       check.errorf(obj, InvalidDeclCycle, "invalid recursive type: %s refers to itself", objName)
+                       check.errorf(obj, InvalidDeclCycle, "invalid recursive type: %s refers to itself", name(obj))
                } else {
-                       check.errorf(obj, InvalidDeclCycle, "invalid cycle in declaration: %s refers to itself", objName)
+                       check.errorf(obj, InvalidDeclCycle, "invalid cycle in declaration: %s refers to itself", name(obj))
                }
                return
        }
 
        err := check.newError(InvalidDeclCycle)
        if tname != nil {
-               err.addf(obj, "invalid recursive type %s", objName)
+               err.addf(obj, "invalid recursive type %s", name(obj))
        } else {
-               err.addf(obj, "invalid cycle in declaration of %s", objName)
+               err.addf(obj, "invalid cycle in declaration of %s", name(obj))
        }
-
-       // "cycle[i] refers to cycle[j]" for (i,j) = (s, s+1), (s+1, s+2), ..., (n, 0), (0,1), ..., (s-1,s) for len(cycle) = n, s = start.
-       n := len(cycle)
-       rotate := func(i int) int { return (i + start) % n }
-       for i := range n {
-               obj := cycle[rotate(i)]
-               next := cycle[rotate(i+1)]
+       // "cycle[i] refers to cycle[j]" for (i,j) = (s,s+1), (s+1,s+2), ..., (n-1,0), (0,1), ..., (s-1,s) for len(cycle) = n, s = start.
+       for i := range cycle {
+               next := cycle[(start+i+1)%len(cycle)]
                err.addf(obj, "%s refers to %s", name(obj), name(next))
+               obj = next
        }
        err.report()
 }

diff --git a/src/go/types/initorder.go b/src/go/types/initorder.go
index 682a63e2d738c55ac0f9be67266efeda8670f235..7625c20667499435b96899318fa38fc4a4f4461d 100644 (file)
--- a/src/go/types/initorder.go
+++ b/src/go/types/initorder.go
@@ -166,10 +166,11 @@ func (check *Checker) reportCycle(cycle []Object) {
 
        err := check.newError(InvalidInitCycle)
        err.addf(obj, "initialization cycle for %s", obj.Name())
-       // "cycle[i] refers to cycle[j]" for (i,j) = (0, n-1), (n-1, n-2), ..., (1,0) for len(cycle) = n.
+       // "cycle[i] refers to cycle[j]" for (i,j) = (0,n-1), (n-1,n-2), ..., (1,0) for len(cycle) = n.
        for j := len(cycle) - 1; j >= 0; j-- {
-               err.addf(obj, "%s refers to %s", obj.Name(), cycle[j].Name())
-               obj = cycle[j]
+               next := cycle[j]
+               err.addf(obj, "%s refers to %s", obj.Name(), next.Name())
+               obj = next
        }
        err.report()
 }