[dev.typeparams] cmd/compile/internal/types2: better names for things (cleanup)

- use the symbol 𝓤 (as in 𝓤niverse) instead of ⊤ to denote the set
  of all types (for better readabilty, ⊤ is hard to distinguish from
  T in some fonts)

- use isAll instead of isTop to test for the set of all types

- use allTermlist instead of topTermlist to denote the termlist
  representing all types

Change-Id: Idcb0b3398782b38653338e65173c0dbb935e430a
Reviewed-on: https://go-review.googlesource.com/c/go/+/339891
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

8 files changed, 100 insertions, 101 deletions

diff --git a/src/cmd/compile/internal/types2/instantiate.go b/src/cmd/compile/internal/types2/instantiate.go
index b7ea193a06..0bb4ac956b 100644
--- a/src/cmd/compile/internal/types2/instantiate.go
+++ b/src/cmd/compile/internal/types2/instantiate.go
@@ -174,7 +174,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
 	// if iface is comparable, targ must be comparable
 	// TODO(gri) the error messages needs to be better, here
 	if iface.IsComparable() && !Comparable(targ) {
-		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsTop() {
+		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsAll() {
 			check.softErrorf(pos, "%s has no constraints", targ)
 			return false
 		}
diff --git a/src/cmd/compile/internal/types2/interface.go b/src/cmd/compile/internal/types2/interface.go
index aa7d0b05a0..f763f8ff44 100644
--- a/src/cmd/compile/internal/types2/interface.go
+++ b/src/cmd/compile/internal/types2/interface.go
@@ -92,7 +92,7 @@ func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
 func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
 
 // Empty reports whether t is the empty interface.
-func (t *Interface) Empty() bool { return t.typeSet().IsTop() }
+func (t *Interface) Empty() bool { return t.typeSet().IsAll() }
 
 // IsComparable reports whether each type in interface t's type set is comparable.
 func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
diff --git a/src/cmd/compile/internal/types2/termlist.go b/src/cmd/compile/internal/types2/termlist.go
index 07056edd97..378ba6b8f4 100644
--- a/src/cmd/compile/internal/types2/termlist.go
+++ b/src/cmd/compile/internal/types2/termlist.go
@@ -13,9 +13,9 @@ import "bytes"
 // normal form.
 type termlist []*term
 
-// topTermlist represents the set of all types.
+// allTermlist represents the set of all types.
 // It is in normal form.
-var topTermlist = termlist{new(term)}
+var allTermlist = termlist{new(term)}
 
 // String prints the termlist exactly (without normalization).
 func (xl termlist) String() string {
@@ -45,9 +45,9 @@ func (xl termlist) isEmpty() bool {
 	return true
 }
 
-// isTop reports whether the termlist xl represents the set of all types.
-func (xl termlist) isTop() bool {
-	// If there's a ⊤ (top) term, the entire list is ⊤ (top).
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
 	// If the termlist is in normal form, this requires at most
 	// one iteration.
 	for _, x := range xl {
@@ -74,14 +74,14 @@ func (xl termlist) norm() termlist {
 				continue
 			}
 			if u1, u2 := xi.union(xj); u2 == nil {
-				// If we encounter a ⊤ (top) term, the entire
-				// list is ⊤ (top). Exit early.
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
 				// (Note that this is not just an optimization;
-				// if we continue, we may end up with a ⊤ term
+				// if we continue, we may end up with a 𝓤 term
 				// and other terms and the result would not be
 				// in normal form.)
 				if u1.typ == nil {
-					return topTermlist
+					return allTermlist
 				}
 				xi = u1
 				used[j] = true // xj is now unioned into xi - ignore it in future iterations
@@ -92,11 +92,11 @@ func (xl termlist) norm() termlist {
 	return rl
 }
 
-// If the type set represented by xl is specified by a single (non-⊤) term,
+// If the type set represented by xl is specified by a single (non-𝓤) term,
 // structuralType returns that type. Otherwise it returns nil.
 func (xl termlist) structuralType() Type {
 	if nl := xl.norm(); len(nl) == 1 {
-		return nl[0].typ // if nl.isTop() then typ is nil, which is ok
+		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
 	}
 	return nil
 }
diff --git a/src/cmd/compile/internal/types2/termlist_test.go b/src/cmd/compile/internal/types2/termlist_test.go
index c36baeb86f..706b4c9756 100644
--- a/src/cmd/compile/internal/types2/termlist_test.go
+++ b/src/cmd/compile/internal/types2/termlist_test.go
@@ -21,20 +21,20 @@ func maketl(s string) termlist {
 }
 
 func TestTermlistTop(t *testing.T) {
-	if !topTermlist.isTop() {
-		t.Errorf("topTermlist is not top")
+	if !allTermlist.isAll() {
+		t.Errorf("allTermlist is not the set of all types")
 	}
 }
 
 func TestTermlistString(t *testing.T) {
 	for _, want := range []string{
 		"∅",
-		"⊤",
+		"𝓤",
 		"int",
 		"~int",
 		"∅ ∪ ∅",
-		"⊤ ∪ ⊤",
-		"∅ ∪ ⊤ ∪ int",
+		"𝓤 ∪ 𝓤",
+		"∅ ∪ 𝓤 ∪ int",
 	} {
 		if got := maketl(want).String(); got != want {
 			t.Errorf("(%v).String() == %v", want, got)
@@ -46,9 +46,9 @@ func TestTermlistIsEmpty(t *testing.T) {
 	for test, want := range map[string]bool{
 		"∅":         true,
 		"∅ ∪ ∅":     true,
-		"∅ ∪ ∅ ∪ ⊤": false,
-		"⊤":         false,
-		"⊤ ∪ int":   false,
+		"∅ ∪ ∅ ∪ 𝓤": false,
+		"𝓤":         false,
+		"𝓤 ∪ int":   false,
 	} {
 		xl := maketl(test)
 		got := xl.isEmpty()
@@ -58,19 +58,19 @@ func TestTermlistIsEmpty(t *testing.T) {
 	}
 }
 
-func TestTermlistIsTop(t *testing.T) {
+func TestTermlistIsAll(t *testing.T) {
 	for test, want := range map[string]bool{
 		"∅":             false,
 		"∅ ∪ ∅":         false,
 		"int ∪ ~string": false,
-		"∅ ∪ ∅ ∪ ⊤":     true,
-		"⊤":             true,
-		"⊤ ∪ int":       true,
+		"∅ ∪ ∅ ∪ 𝓤":     true,
+		"𝓤":             true,
+		"𝓤 ∪ int":       true,
 	} {
 		xl := maketl(test)
-		got := xl.isTop()
+		got := xl.isAll()
 		if got != want {
-			t.Errorf("(%v).isTop() == %v; want %v", test, got, want)
+			t.Errorf("(%v).isAll() == %v; want %v", test, got, want)
 		}
 	}
 }
@@ -82,10 +82,10 @@ func TestTermlistNorm(t *testing.T) {
 		{"∅", "∅"},
 		{"∅ ∪ ∅", "∅"},
 		{"∅ ∪ int", "int"},
-		{"⊤ ∪ int", "⊤"},
+		{"𝓤 ∪ int", "𝓤"},
 		{"~int ∪ int", "~int"},
 		{"int ∪ ~string ∪ int", "int ∪ ~string"},
-		{"~int ∪ string ∪ ⊤ ∪ ~string ∪ int", "⊤"},
+		{"~int ∪ string ∪ 𝓤 ∪ ~string ∪ int", "𝓤"},
 	} {
 		xl := maketl(test.xl)
 		got := maketl(test.xl).norm()
@@ -106,7 +106,7 @@ func TestTermlistStructuralType(t *testing.T) {
 
 	for test, want := range map[string]string{
 		"∅":                 "nil",
-		"⊤":                 "nil",
+		"𝓤":                 "nil",
 		"int":               "int",
 		"~int":              "int",
 		"~int ∪ string":     "nil",
@@ -128,15 +128,15 @@ func TestTermlistUnion(t *testing.T) {
 	}{
 
 		{"∅", "∅", "∅"},
-		{"∅", "⊤", "⊤"},
+		{"∅", "𝓤", "𝓤"},
 		{"∅", "int", "int"},
-		{"⊤", "~int", "⊤"},
+		{"𝓤", "~int", "𝓤"},
 		{"int", "~int", "~int"},
 		{"int", "string", "int ∪ string"},
 		{"int ∪ string", "~string", "int ∪ ~string"},
 		{"~int ∪ string", "~string ∪ int", "~int ∪ ~string"},
 		{"~int ∪ string ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
-		{"~int ∪ string ∪ ⊤", "~string ∪ int", "⊤"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "𝓤"},
 	} {
 		xl := maketl(test.xl)
 		yl := maketl(test.yl)
@@ -153,15 +153,15 @@ func TestTermlistIntersect(t *testing.T) {
 	}{
 
 		{"∅", "∅", "∅"},
-		{"∅", "⊤", "∅"},
+		{"∅", "𝓤", "∅"},
 		{"∅", "int", "∅"},
-		{"⊤", "~int", "~int"},
+		{"𝓤", "~int", "~int"},
 		{"int", "~int", "int"},
 		{"int", "string", "∅"},
 		{"int ∪ string", "~string", "string"},
 		{"~int ∪ string", "~string ∪ int", "int ∪ string"},
 		{"~int ∪ string ∪ ∅", "~string ∪ int", "int ∪ string"},
-		{"~int ∪ string ∪ ⊤", "~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "int ∪ ~string"},
 	} {
 		xl := maketl(test.xl)
 		yl := maketl(test.yl)
@@ -178,10 +178,10 @@ func TestTermlistEqual(t *testing.T) {
 		want   bool
 	}{
 		{"∅", "∅", true},
-		{"∅", "⊤", false},
-		{"⊤", "⊤", true},
-		{"⊤ ∪ int", "⊤", true},
-		{"⊤ ∪ int", "string ∪ ⊤", true},
+		{"∅", "𝓤", false},
+		{"𝓤", "𝓤", true},
+		{"𝓤 ∪ int", "𝓤", true},
+		{"𝓤 ∪ int", "string ∪ 𝓤", true},
 		{"int ∪ ~string", "string ∪ int", false},
 		{"int ∪ ~string ∪ ∅", "string ∪ int ∪ ~string", true},
 	} {
@@ -200,14 +200,14 @@ func TestTermlistIncludes(t *testing.T) {
 		want    bool
 	}{
 		{"∅", "int", false},
-		{"⊤", "int", true},
+		{"𝓤", "int", true},
 		{"~int", "int", true},
 		{"int", "string", false},
 		{"~int", "string", false},
 		{"int ∪ string", "string", true},
 		{"~int ∪ string", "int", true},
 		{"~int ∪ string ∪ ∅", "string", true},
-		{"~string ∪ ∅ ∪ ⊤", "int", true},
+		{"~string ∪ ∅ ∪ 𝓤", "int", true},
 	} {
 		xl := maketl(test.xl)
 		yl := testTerm(test.typ).typ
@@ -224,12 +224,12 @@ func TestTermlistSupersetOf(t *testing.T) {
 		want    bool
 	}{
 		{"∅", "∅", true},
-		{"∅", "⊤", false},
+		{"∅", "𝓤", false},
 		{"∅", "int", false},
-		{"⊤", "∅", true},
-		{"⊤", "⊤", true},
-		{"⊤", "int", true},
-		{"⊤", "~int", true},
+		{"𝓤", "∅", true},
+		{"𝓤", "𝓤", true},
+		{"𝓤", "int", true},
+		{"𝓤", "~int", true},
 		{"~int", "int", true},
 		{"~int", "~int", true},
 		{"int", "~int", false},
@@ -239,7 +239,7 @@ func TestTermlistSupersetOf(t *testing.T) {
 		{"int ∪ string", "~string", false},
 		{"~int ∪ string", "int", true},
 		{"~int ∪ string ∪ ∅", "string", true},
-		{"~string ∪ ∅ ∪ ⊤", "int", true},
+		{"~string ∪ ∅ ∪ 𝓤", "int", true},
 	} {
 		xl := maketl(test.xl)
 		y := testTerm(test.typ)
@@ -256,16 +256,16 @@ func TestTermlistSubsetOf(t *testing.T) {
 		want   bool
 	}{
 		{"∅", "∅", true},
-		{"∅", "⊤", true},
-		{"⊤", "∅", false},
-		{"⊤", "⊤", true},
+		{"∅", "𝓤", true},
+		{"𝓤", "∅", false},
+		{"𝓤", "𝓤", true},
 		{"int", "int ∪ string", true},
 		{"~int", "int ∪ string", false},
 		{"~int", "string ∪ string ∪ int ∪ ~int", true},
 		{"int ∪ string", "string", false},
 		{"int ∪ string", "string ∪ int", true},
 		{"int ∪ ~string", "string ∪ int", false},
-		{"int ∪ ~string", "string ∪ int ∪ ⊤", true},
+		{"int ∪ ~string", "string ∪ int ∪ 𝓤", true},
 		{"int ∪ ~string", "string ∪ int ∪ ∅ ∪ string", false},
 	} {
 		xl := maketl(test.xl)
diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
index c5fcb97ff9..83df51389b 100644
--- a/src/cmd/compile/internal/types2/typeset.go
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -25,17 +25,19 @@ type TypeSet struct {
 // IsEmpty reports whether type set s is the empty set.
 func (s *TypeSet) IsEmpty() bool { return s.terms.isEmpty() }
 
-// IsTop reports whether type set s is the set of all types (corresponding to the empty interface).
-func (s *TypeSet) IsTop() bool { return !s.comparable && len(s.methods) == 0 && s.terms.isTop() }
+// IsAll reports whether type set s is the set of all types (corresponding to the empty interface).
+func (s *TypeSet) IsAll() bool {
+	return !s.comparable && len(s.methods) == 0 && s.terms.isAll()
+}
 
 // TODO(gri) IsMethodSet is not a great name for this predicate. Find a better one.
 
 // IsMethodSet reports whether the type set s is described by a single set of methods.
-func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isTop() }
+func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isAll() }
 
 // IsComparable reports whether each type in the set is comparable.
 func (s *TypeSet) IsComparable() bool {
-	if s.terms.isTop() {
+	if s.terms.isAll() {
 		return s.comparable
 	}
 	return s.is(func(t *term) bool {
@@ -67,8 +69,8 @@ func (s *TypeSet) String() string {
 	switch {
 	case s.IsEmpty():
 		return "∅"
-	case s.IsTop():
-		return "⊤"
+	case s.IsAll():
+		return "𝓤"
 	}
 
 	hasMethods := len(s.methods) > 0
@@ -103,7 +105,7 @@ func (s *TypeSet) String() string {
 // ----------------------------------------------------------------------------
 // Implementation
 
-func (s *TypeSet) hasTerms() bool             { return !s.terms.isTop() }
+func (s *TypeSet) hasTerms() bool             { return !s.terms.isAll() }
 func (s *TypeSet) structuralType() Type       { return s.terms.structuralType() }
 func (s *TypeSet) includes(t Type) bool       { return s.terms.includes(t) }
 func (s1 *TypeSet) subsetOf(s2 *TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
@@ -156,7 +158,7 @@ func (s *TypeSet) underIs(f func(Type) bool) bool {
 }
 
 // topTypeSet may be used as type set for the empty interface.
-var topTypeSet = TypeSet{terms: topTermlist}
+var topTypeSet = TypeSet{terms: allTermlist}
 
 // computeInterfaceTypeSet may be called with check == nil.
 func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *TypeSet {
@@ -195,7 +197,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T
 	// have valid interfaces. Mark the interface as complete to avoid
 	// infinite recursion if the validType check occurs later for some
 	// reason.
-	ityp.tset = &TypeSet{terms: topTermlist} // TODO(gri) is this sufficient?
+	ityp.tset = &TypeSet{terms: allTermlist} // TODO(gri) is this sufficient?
 
 	// Methods of embedded interfaces are collected unchanged; i.e., the identity
 	// of a method I.m's Func Object of an interface I is the same as that of
@@ -256,7 +258,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T
 	}
 
 	// collect embedded elements
-	var allTerms = topTermlist
+	var allTerms = allTermlist
 	for i, typ := range ityp.embeddeds {
 		// The embedding position is nil for imported interfaces
 		// and also for interface copies after substitution (but
diff --git a/src/cmd/compile/internal/types2/typeterm.go b/src/cmd/compile/internal/types2/typeterm.go
index 59a89cb004..8edbefa579 100644
--- a/src/cmd/compile/internal/types2/typeterm.go
+++ b/src/cmd/compile/internal/types2/typeterm.go
@@ -4,13 +4,10 @@
 
 package types2
 
-// TODO(gri) use a different symbol instead of ⊤ for the set of all types
-//           (⊤ is hard to distinguish from T in some fonts)
-
 // A term describes elementary type sets:
 //
 //   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
-//   ⊤:  &term{}          == ⊤                      // set of all types
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
 //   T:  &term{false, T}  == {T}                    // set of type T
 //  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
 //
@@ -24,7 +21,7 @@ func (x *term) String() string {
 	case x == nil:
 		return "∅"
 	case x.typ == nil:
-		return "⊤"
+		return "𝓤"
 	case x.tilde:
 		return "~" + x.typ.String()
 	default:
@@ -41,7 +38,7 @@ func (x *term) equal(y *term) bool {
 	case x.typ == nil || y.typ == nil:
 		return x.typ == y.typ
 	}
-	// ∅ ⊂ x, y ⊂ ⊤
+	// ∅ ⊂ x, y ⊂ 𝓤
 
 	return x.tilde == y.tilde && Identical(x.typ, y.typ)
 }
@@ -57,11 +54,11 @@ func (x *term) union(y *term) (_, _ *term) {
 	case y == nil:
 		return x, nil // x ∪ ∅ == x
 	case x.typ == nil:
-		return x, nil // ⊤ ∪ y == ⊤
+		return x, nil // 𝓤 ∪ y == 𝓤
 	case y.typ == nil:
-		return y, nil // x ∪ ⊤ == ⊤
+		return y, nil // x ∪ 𝓤 == 𝓤
 	}
-	// ∅ ⊂ x, y ⊂ ⊤
+	// ∅ ⊂ x, y ⊂ 𝓤
 
 	if x.disjoint(y) {
 		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
@@ -85,11 +82,11 @@ func (x *term) intersect(y *term) *term {
 	case x == nil || y == nil:
 		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
 	case x.typ == nil:
-		return y // ⊤ ∩ y == y
+		return y // 𝓤 ∩ y == y
 	case y.typ == nil:
-		return x // x ∩ ⊤ == x
+		return x // x ∩ 𝓤 == x
 	}
-	// ∅ ⊂ x, y ⊂ ⊤
+	// ∅ ⊂ x, y ⊂ 𝓤
 
 	if x.disjoint(y) {
 		return nil // x ∩ y == ∅ if x ∩ y == ∅
@@ -113,9 +110,9 @@ func (x *term) includes(t Type) bool {
 	case x == nil:
 		return false // t ∈ ∅ == false
 	case x.typ == nil:
-		return true // t ∈ ⊤ == true
+		return true // t ∈ 𝓤 == true
 	}
-	// ∅ ⊂ x ⊂ ⊤
+	// ∅ ⊂ x ⊂ 𝓤
 
 	u := t
 	if x.tilde {
@@ -133,11 +130,11 @@ func (x *term) subsetOf(y *term) bool {
 	case y == nil:
 		return false // x ⊆ ∅ == false since x != ∅
 	case y.typ == nil:
-		return true // x ⊆ ⊤ == true
+		return true // x ⊆ 𝓤 == true
 	case x.typ == nil:
-		return false // ⊤ ⊆ y == false since y != ⊤
+		return false // 𝓤 ⊆ y == false since y != 𝓤
 	}
-	// ∅ ⊂ x, y ⊂ ⊤
+	// ∅ ⊂ x, y ⊂ 𝓤
 
 	if x.disjoint(y) {
 		return false // x ⊆ y == false if x ∩ y == ∅
diff --git a/src/cmd/compile/internal/types2/typeterm_test.go b/src/cmd/compile/internal/types2/typeterm_test.go
index cc4e30d989..a8cc362f56 100644
--- a/src/cmd/compile/internal/types2/typeterm_test.go
+++ b/src/cmd/compile/internal/types2/typeterm_test.go
@@ -11,7 +11,7 @@ import (
 
 var testTerms = map[string]*term{
 	"∅":       nil,
-	"⊤":       {},
+	"𝓤":       {},
 	"int":     {false, Typ[Int]},
 	"~int":    {true, Typ[Int]},
 	"string":  {false, Typ[String]},
@@ -46,14 +46,14 @@ func testTerm(name string) *term {
 func TestTermEqual(t *testing.T) {
 	for _, test := range []string{
 		"∅ ∅ T",
-		"⊤ ⊤ T",
+		"𝓤 𝓤 T",
 		"int int T",
 		"~int ~int T",
-		"∅ ⊤ F",
+		"∅ 𝓤 F",
 		"∅ int F",
 		"∅ ~int F",
-		"⊤ int F",
-		"⊤ ~int F",
+		"𝓤 int F",
+		"𝓤 ~int F",
 		"int ~int F",
 	} {
 		args := split(test, 3)
@@ -74,12 +74,12 @@ func TestTermEqual(t *testing.T) {
 func TestTermUnion(t *testing.T) {
 	for _, test := range []string{
 		"∅ ∅ ∅ ∅",
-		"∅ ⊤ ⊤ ∅",
+		"∅ 𝓤 𝓤 ∅",
 		"∅ int int ∅",
 		"∅ ~int ~int ∅",
-		"⊤ ⊤ ⊤ ∅",
-		"⊤ int ⊤ ∅",
-		"⊤ ~int ⊤ ∅",
+		"𝓤 𝓤 𝓤 ∅",
+		"𝓤 int 𝓤 ∅",
+		"𝓤 ~int 𝓤 ∅",
 		"int int int ∅",
 		"int ~int ~int ∅",
 		"int string int string",
@@ -87,11 +87,11 @@ func TestTermUnion(t *testing.T) {
 		"~int ~string ~int ~string",
 
 		// union is symmetric, but the result order isn't - repeat symmetric cases explictly
-		"⊤ ∅ ⊤ ∅",
+		"𝓤 ∅ 𝓤 ∅",
 		"int ∅ int ∅",
 		"~int ∅ ~int ∅",
-		"int ⊤ ⊤ ∅",
-		"~int ⊤ ⊤ ∅",
+		"int 𝓤 𝓤 ∅",
+		"~int 𝓤 𝓤 ∅",
 		"~int int ~int ∅",
 		"string int string int",
 		"~string int ~string int",
@@ -111,12 +111,12 @@ func TestTermUnion(t *testing.T) {
 func TestTermIntersection(t *testing.T) {
 	for _, test := range []string{
 		"∅ ∅ ∅",
-		"∅ ⊤ ∅",
+		"∅ 𝓤 ∅",
 		"∅ int ∅",
 		"∅ ~int ∅",
-		"⊤ ⊤ ⊤",
-		"⊤ int int",
-		"⊤ ~int ~int",
+		"𝓤 𝓤 𝓤",
+		"𝓤 int int",
+		"𝓤 ~int ~int",
 		"int int int",
 		"int ~int int",
 		"int string ∅",
@@ -141,7 +141,7 @@ func TestTermIntersection(t *testing.T) {
 func TestTermIncludes(t *testing.T) {
 	for _, test := range []string{
 		"∅ int F",
-		"⊤ int T",
+		"𝓤 int T",
 		"int int T",
 		"~int int T",
 		"string int F",
@@ -160,14 +160,14 @@ func TestTermIncludes(t *testing.T) {
 func TestTermSubsetOf(t *testing.T) {
 	for _, test := range []string{
 		"∅ ∅ T",
-		"⊤ ⊤ T",
+		"𝓤 𝓤 T",
 		"int int T",
 		"~int ~int T",
-		"∅ ⊤ T",
+		"∅ 𝓤 T",
 		"∅ int T",
 		"∅ ~int T",
-		"⊤ int F",
-		"⊤ ~int F",
+		"𝓤 int F",
+		"𝓤 ~int F",
 		"int ~int T",
 	} {
 		args := split(test, 3)
diff --git a/src/cmd/compile/internal/types2/universe.go b/src/cmd/compile/internal/types2/universe.go
index 55bf0982b3..f14c079222 100644
--- a/src/cmd/compile/internal/types2/universe.go
+++ b/src/cmd/compile/internal/types2/universe.go
@@ -99,7 +99,7 @@ func defPredeclaredTypes() {
 	{
 		obj := NewTypeName(nopos, nil, "comparable", nil)
 		obj.setColor(black)
-		ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, topTermlist}}
+		ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, allTermlist}}
 		NewNamed(obj, ityp, nil)
 		def(obj)
 	}