fix(ipam): only suppress diffs when IP host part is identical

internal/services/ipam/helpers.go

@@ -43,30 +43,19 @@ func NewAPIWithRegionAndID(m any, id string) (*ipam.API, scw.Region, string, err
 	return ipamAPI, region, ID, err
 }
 
-func diffSuppressFuncStandaloneIPandCIDR(_, oldValue, newValue string, _ *schema.ResourceData) bool {
-	oldIP, oldNet, errOld := net.ParseCIDR(oldValue)
-	if errOld != nil {
-		oldIP = net.ParseIP(oldValue)
-	}
-
-	newIP, newNet, errNew := net.ParseCIDR(newValue)
-	if errNew != nil {
-		newIP = net.ParseIP(newValue)
-	}
-
-	if oldIP != nil && newIP != nil && oldIP.Equal(newIP) {
-		return true
-	}
+func DiffSuppressFuncStandaloneIPandCIDR(_, oldValue, newValue string, _ *schema.ResourceData) bool {
+	parseIPOrCIDR := func(s string) net.IP {
+		if ip, _, err := net.ParseCIDR(s); err == nil {
+			return ip
+		}
 
-	if oldNet != nil && newIP != nil && oldNet.Contains(newIP) {
-		return true
+		return net.ParseIP(s)
 	}
 
-	if newNet != nil && oldIP != nil && newNet.Contains(oldIP) {
-		return true
-	}
+	oldIP := parseIPOrCIDR(oldValue)
+	newIP := parseIPOrCIDR(newValue)
 
-	return false
+	return oldIP != nil && newIP != nil && oldIP.Equal(newIP)
 }
 
 type GetResourcePrivateIPsOptions struct {

internal/services/ipam/helpers_test.go

@@ -0,0 +1,86 @@
+package ipam_test
+
+import (
+	"testing"
+
+	"github.com/scaleway/terraform-provider-scaleway/v2/internal/services/ipam"
+)
+
+func TestDiffSuppress_IPAMIP(t *testing.T) {
+	tests := []struct {
+		name     string
+		oldValue string
+		newValue string
+		want     bool
+	}{
+		{
+			name:     "IP == IP",
+			oldValue: "172.16.32.7",
+			newValue: "172.16.32.7",
+			want:     true,
+		},
+		{
+			name:     "IP == IP/CIDR same host",
+			oldValue: "172.16.32.7/22",
+			newValue: "172.16.32.7",
+			want:     true,
+		},
+		{
+			name:     "IP/CIDR == IP same host (reversed)",
+			oldValue: "172.16.32.7",
+			newValue: "172.16.32.7/22",
+			want:     true,
+		},
+		{
+			name:     "Different host within same CIDR is NOT suppressed",
+			oldValue: "172.16.32.7/22",
+			newValue: "172.16.32.8",
+			want:     false,
+		},
+		{
+			name:     "Different host (plain IPs) is NOT suppressed",
+			oldValue: "172.16.32.7",
+			newValue: "172.16.32.8",
+			want:     false,
+		},
+		{
+			name:     "Equal but with /32 single-host CIDR",
+			oldValue: "10.0.0.1/32",
+			newValue: "10.0.0.1",
+			want:     true,
+		},
+		{
+			name:     "Broader CIDR vs network address should NOT suppress",
+			oldValue: "10.0.0.1/24",
+			newValue: "10.0.0.0",
+			want:     false,
+		},
+		{
+			name:     "Invalid old value -> not suppressed",
+			oldValue: "not-an-ip",
+			newValue: "10.0.0.1",
+			want:     false,
+		},
+		{
+			name:     "Invalid new value -> not suppressed",
+			oldValue: "10.0.0.1",
+			newValue: "bad/32",
+			want:     false,
+		},
+		{
+			name:     "Both invalid -> not suppressed",
+			oldValue: "nope",
+			newValue: "nope2",
+			want:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ipam.DiffSuppressFuncStandaloneIPandCIDR("", tt.oldValue, tt.newValue, nil)
+			if got != tt.want {
+				t.Fatalf("diffSuppress(%q, %q) = %v, want %v", tt.oldValue, tt.newValue, got, tt.want)
+			}
+		})
+	}
+}

internal/services/ipam/ip.go

@@ -38,7 +38,7 @@ func ResourceIP() *schema.Resource {
 				ForceNew:         true,
 				Description:      "Request a specific IP in the requested source pool",
 				ValidateFunc:     validation.IsIPAddress,
-				DiffSuppressFunc: diffSuppressFuncStandaloneIPandCIDR,
+				DiffSuppressFunc: DiffSuppressFuncStandaloneIPandCIDR,
 			},
 			"source": {
 				Type:        schema.TypeList,