From 1bddb66b7c6bd32eae3bcbf8ae9eb51398166ea9 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Fri, 13 Sep 2019 22:18:19 -0700
Subject: [PATCH] go/types: more operators supported by contracts

Change-Id: I03493508813d13dd1a16cd675de68170da14b29f
---
 src/go/types/predicates.go          | 57 ++++++++---------------------
 src/go/types/testdata/contracts.go2 | 21 +++++++++--
 2 files changed, 34 insertions(+), 44 deletions(-)

diff --git a/src/go/types/predicates.go b/src/go/types/predicates.go
index f4e332d07a..5f5e14f75d 100644
--- a/src/go/types/predicates.go
+++ b/src/go/types/predicates.go
@@ -16,40 +16,23 @@ func isNamed(typ Type) bool {
 	return ok
 }
 
-func isBoolean(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsBoolean != 0
+func is(typ Type, what BasicInfo) bool {
+	switch t := typ.Underlying().(type) {
+	case *Basic:
+		return t.info&what != 0
+	case *TypeParam:
+		return t.contr.ifaceAt(t.index).is(func(typ Type) bool { return is(typ, what) })
+	}
+	return false
 }
 
-func isInteger(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsInteger != 0
-}
-
-func isUnsigned(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsUnsigned != 0
-}
-
-func isFloat(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsFloat != 0
-}
-
-func isComplex(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsComplex != 0
-}
-
-func isNumeric(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsNumeric != 0
-}
-
-func isString(typ Type) bool {
-	t, ok := typ.Underlying().(*Basic)
-	return ok && t.info&IsString != 0
-}
+func isBoolean(typ Type) bool  { return is(typ, IsBoolean) }
+func isInteger(typ Type) bool  { return is(typ, IsInteger) }
+func isUnsigned(typ Type) bool { return is(typ, IsUnsigned) }
+func isFloat(typ Type) bool    { return is(typ, IsFloat) }
+func isComplex(typ Type) bool  { return is(typ, IsComplex) }
+func isNumeric(typ Type) bool  { return is(typ, IsNumeric) }
+func isString(typ Type) bool   { return is(typ, IsString) }
 
 func isTyped(typ Type) bool {
 	t, ok := typ.Underlying().(*Basic)
@@ -61,15 +44,7 @@ func isUntyped(typ Type) bool {
 	return ok && t.info&IsUntyped != 0
 }
 
-func isOrdered(typ Type) bool {
-	switch t := typ.Underlying().(type) {
-	case *Basic:
-		return t.info&IsOrdered != 0
-	case *TypeParam:
-		return t.contr.ifaceAt(t.index).is(isOrdered)
-	}
-	return false
-}
+func isOrdered(typ Type) bool { return is(typ, IsOrdered) }
 
 func isConstType(typ Type) bool {
 	t, ok := typ.Underlying().(*Basic)
diff --git a/src/go/types/testdata/contracts.go2 b/src/go/types/testdata/contracts.go2
index ed19849031..ef128e1115 100644
--- a/src/go/types/testdata/contracts.go2
+++ b/src/go/types/testdata/contracts.go2
@@ -119,13 +119,28 @@ var _ T2(struct{x int})
 
 // Use of contracts in parameterized functions
 
-contract SignedInteger(T) {
-        T int8, int16, int32, int64, int
+contract Ordered(T) {
+        T int8, int16, int32, int64, int,
+          uint8, uint16, uint32, uint64, uint,
+          float32, float64, string, rune
 }
 
-func min(type T SignedInteger)(x, y T) T {
+func min(type T Ordered)(x, y T) T {
         if x < y {
                 return x
         }
         return y
+}
+
+contract Integer(T) {
+        T int8, int16, int32, int64, int,
+          uint8, uint16, uint32, uint64, uint
+}
+
+func sum(type T Integer)(data []T) T {
+        var s T
+        for _, x := range data {
+                s += x
+        }
+        return s
 }
\ No newline at end of file