treewide: initialize empty structs with var

Change-Id: I72d3993eaf5fe57c77b1dda8218e36a8cc11813d
Reviewed-on: https://review.monogon.dev/c/monogon/+/3108
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/event/etcd/etcd_test.go b/metropolis/pkg/event/etcd/etcd_test.go
index c6d50b1..bd96363 100644
--- a/metropolis/pkg/event/etcd/etcd_test.go
+++ b/metropolis/pkg/event/etcd/etcd_test.go
@@ -63,7 +63,7 @@
 // it starts the watcher. This is used to test potential race conditions
 // present between these two steps.
 func setRaceWg[T any](w event.Watcher[T]) *sync.WaitGroup {
-	wg := sync.WaitGroup{}
+	var wg sync.WaitGroup
 	w.(*watcher[T]).testRaceWG = &wg
 	return &wg
 }
@@ -72,7 +72,7 @@
 // thie WG after an etcd watch channel is created. This is used in tests to
 // ensure that the watcher is fully created before it is tested.
 func setSetupWg[T any](w event.Watcher[T]) *sync.WaitGroup {
-	wg := sync.WaitGroup{}
+	var wg sync.WaitGroup
 	w.(*watcher[T]).testSetupWG = &wg
 	return &wg
 }
diff --git a/metropolis/pkg/event/memory/example_test.go b/metropolis/pkg/event/memory/example_test.go
index 583650c..1ae12c6 100644
--- a/metropolis/pkg/event/memory/example_test.go
+++ b/metropolis/pkg/event/memory/example_test.go
@@ -82,7 +82,7 @@
 	defer ctxC()
 
 	// Create a fake NetworkService.
-	ns := NetworkService{}
+	var ns NetworkService
 
 	// Run an /etc/hosts updater. It will watch for updates from the NetworkService
 	// about the current IP address of the node.
diff --git a/metropolis/pkg/event/memory/memory_test.go b/metropolis/pkg/event/memory/memory_test.go
index 80ac575..eec0a37 100644
--- a/metropolis/pkg/event/memory/memory_test.go
+++ b/metropolis/pkg/event/memory/memory_test.go
@@ -71,7 +71,7 @@
 		Sync: true,
 	}
 	values := make(chan int, 100)
-	wg := sync.WaitGroup{}
+	var wg sync.WaitGroup
 	wg.Add(1)
 	go func() {
 		ctx := context.Background()
diff --git a/metropolis/pkg/tpm/eventlog/eventlog.go b/metropolis/pkg/tpm/eventlog/eventlog.go
index 036185a..dbfeae0 100644
--- a/metropolis/pkg/tpm/eventlog/eventlog.go
+++ b/metropolis/pkg/tpm/eventlog/eventlog.go
@@ -489,8 +489,8 @@
 	// TODO(ericchiang): Check errata? Or do we expect that to change in ways
 	// we're okay with?
 
-	specAlg := specAlgSize{}
-	e := specIDEvent{}
+	var specAlg specAlgSize
+	var e specIDEvent
 	for i := 0; i < int(header.NumAlgs); i++ {
 		if err := binary.Read(r, binary.LittleEndian, &specAlg); err != nil {
 			return nil, fmt.Errorf("reading algorithm: %v", err)
diff --git a/metropolis/pkg/tpm/eventlog/internal/events.go b/metropolis/pkg/tpm/eventlog/internal/events.go
index 3a719ab..eb121b2 100644
--- a/metropolis/pkg/tpm/eventlog/internal/events.go
+++ b/metropolis/pkg/tpm/eventlog/internal/events.go
@@ -275,7 +275,7 @@
 		// Being passed an empty signature list here appears to be valid
 		return nil, nil, nil
 	}
-	signatures := efiSignatureList{}
+	var signatures efiSignatureList
 	buf := bytes.NewReader(b)
 	var certificates []x509.Certificate
 	var hashes [][]byte
@@ -297,7 +297,7 @@
 		switch signatureType {
 		case certX509SigGUID: // X509 certificate
 			for sigOffset := 0; uint32(sigOffset) < signatures.Header.SignatureListSize-28; {
-				signature := efiSignatureData{}
+				var signature efiSignatureData
 				signature.SignatureData = make([]byte, signatures.Header.SignatureSize-16)
 				err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner)
 				if err != nil {
@@ -316,7 +316,7 @@
 			}
 		case hashSHA256SigGUID: // SHA256
 			for sigOffset := 0; uint32(sigOffset) < signatures.Header.SignatureListSize-28; {
-				signature := efiSignatureData{}
+				var signature efiSignatureData
 				signature.SignatureData = make([]byte, signatures.Header.SignatureSize-16)
 				err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner)
 				if err != nil {
@@ -375,7 +375,7 @@
 	}
 
 	buf := bytes.NewReader(b)
-	signature := EFISignatureData{}
+	var signature EFISignatureData
 	signature.SignatureData = make([]byte, len(b)-16)
 
 	if err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner); err != nil {