From 68c3af2eefd87ddb0c3f2672015238248b8be372 Mon Sep 17 00:00:00 2001
From: Alisdair McDiarmid <alisdair@users.noreply.github.com>
Date: Wed, 25 Mar 2020 14:03:55 -0400
Subject: [PATCH] function/stdlib: Preserve infinity for floor/ceil
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

floor(±infinity) and ceil(±infinity) would previously return the max/min
limit of int64. This could lead to confusing behaviour. Instead, we want
to pass through the infinite value without converting to integer.
---
 cty/function/stdlib/number.go      |  6 ++++++
 cty/function/stdlib/number_test.go | 21 +++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/cty/function/stdlib/number.go b/cty/function/stdlib/number.go
index 48438fe0..7bbe584b 100644
--- a/cty/function/stdlib/number.go
+++ b/cty/function/stdlib/number.go
@@ -375,6 +375,9 @@ var CeilFunc = function.New(&function.Spec{
 		if err := gocty.FromCtyValue(args[0], &val); err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
+		if math.IsInf(val, 0) {
+			return cty.NumberFloatVal(val), nil
+		}
 		return cty.NumberIntVal(int64(math.Ceil(val))), nil
 	},
 })
@@ -394,6 +397,9 @@ var FloorFunc = function.New(&function.Spec{
 		if err := gocty.FromCtyValue(args[0], &val); err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
+		if math.IsInf(val, 0) {
+			return cty.NumberFloatVal(val), nil
+		}
 		return cty.NumberIntVal(int64(math.Floor(val))), nil
 	},
 })
diff --git a/cty/function/stdlib/number_test.go b/cty/function/stdlib/number_test.go
index a8e8420b..14d69bf8 100644
--- a/cty/function/stdlib/number_test.go
+++ b/cty/function/stdlib/number_test.go
@@ -2,6 +2,7 @@ package stdlib
 
 import (
 	"fmt"
+	"math"
 	"math/big"
 	"testing"
 
@@ -806,6 +807,16 @@ func TestCeil(t *testing.T) {
 			cty.NumberFloatVal(2),
 			false,
 		},
+		{
+			cty.NumberFloatVal(math.Inf(1)),
+			cty.NumberFloatVal(math.Inf(1)),
+			false,
+		},
+		{
+			cty.NumberFloatVal(math.Inf(-1)),
+			cty.NumberFloatVal(math.Inf(-1)),
+			false,
+		},
 	}
 
 	for _, test := range tests {
@@ -844,6 +855,16 @@ func TestFloor(t *testing.T) {
 			cty.NumberFloatVal(1),
 			false,
 		},
+		{
+			cty.NumberFloatVal(math.Inf(1)),
+			cty.NumberFloatVal(math.Inf(1)),
+			false,
+		},
+		{
+			cty.NumberFloatVal(math.Inf(-1)),
+			cty.NumberFloatVal(math.Inf(-1)),
+			false,
+		},
 	}
 
 	for _, test := range tests {