From d348d8b4cfc572e34b8b3bb0f9ff6b638d422fbd Mon Sep 17 00:00:00 2001
From: Pat Whittingslow <graded.sp@gmail.com>
Date: Tue, 26 May 2026 10:27:32 -0300
Subject: [PATCH] rp2040: fix `-gc=leaking/none`

---
 GNUmakefile                       | 2 ++
 src/machine/machine_rp2040_usb.go | 2 +-
 src/machine/machine_rp2_usb.go    | 2 +-
 src/runtime/gc_leaking.go         | 5 +++++
 src/runtime/gc_none.go            | 4 ++++
 5 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/GNUmakefile b/GNUmakefile
index 57abe1839..450323a8b 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -784,6 +784,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pico                examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pico -gc=leaking    examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nano-33-ble         examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nano-rp2040         examples/blinky1
diff --git a/src/machine/machine_rp2040_usb.go b/src/machine/machine_rp2040_usb.go
index 7f8210199..538cb0176 100644
--- a/src/machine/machine_rp2040_usb.go
+++ b/src/machine/machine_rp2040_usb.go
@@ -128,7 +128,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 	const ackTimeout = 570
 
 	rp.USBCTRL_REGS.SIE_STATUS.Set(rp.USBCTRL_REGS_SIE_STATUS_ACK_REC)
-	sendUSBPacket(0, []byte{})
+	sendUSBPacket(0, nil)
 
 	// Wait for transfer to complete with a timeout.
 	t := timer.timeElapsed()
diff --git a/src/machine/machine_rp2_usb.go b/src/machine/machine_rp2_usb.go
index aa46aa858..36a0aab54 100644
--- a/src/machine/machine_rp2_usb.go
+++ b/src/machine/machine_rp2_usb.go
@@ -141,7 +141,7 @@ func setEPDataPID(ep uint32, dataOne bool) {
 }
 
 func SendZlp() {
-	sendUSBPacket(0, []byte{})
+	sendUSBPacket(0, nil)
 }
 
 func sendViaEPIn(ep uint32, data []byte, count int) {
diff --git a/src/runtime/gc_leaking.go b/src/runtime/gc_leaking.go
index 24eea44bb..51ae247f7 100644
--- a/src/runtime/gc_leaking.go
+++ b/src/runtime/gc_leaking.go
@@ -8,11 +8,16 @@ package runtime
 
 import (
 	"internal/task"
+	"sync/atomic"
 	"unsafe"
 )
 
 const needsStaticHeap = true
 
+var gcScanState atomic.Uint32
+
+func scanCurrentStack() {}
+
 // Ever-incrementing pointer: no memory is freed.
 var heapptr uintptr
 
diff --git a/src/runtime/gc_none.go b/src/runtime/gc_none.go
index b9e3155e4..3c092c65c 100644
--- a/src/runtime/gc_none.go
+++ b/src/runtime/gc_none.go
@@ -7,6 +7,7 @@ package runtime
 // targets that have far too little RAM even for the leaking memory allocator.
 
 import (
+	"sync/atomic"
 	"unsafe"
 )
 
@@ -15,6 +16,9 @@ const needsStaticHeap = false
 var gcTotalAlloc uint64 // for runtime.MemStats
 var gcMallocs uint64
 var gcFrees uint64
+var gcScanState atomic.Uint32
+
+func scanCurrentStack() {}
 
 func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer