runtime: fatal error in finishsweep_m: "span set block with unpopped elements found in reset

[gopherbot]

#!watchflakes
default <- pkg == "golang.org/x/tools/gopls/internal/golang.test" && test == ""

Issue created automatically to collect these failures.

Example (log):

# golang.org/x/tools/gopls/internal/golang.test
fatal error: span set block with unpopped elements found in reset

runtime stack:
runtime.throw({0x737979b?, 0x103d9000?})
	runtime/panic.go:1229 +0x48 fp=0x70000f060ed8 sp=0x70000f060ea8 pc=0x710b9e8
runtime.(*spanSet).reset(0x768ff90?)
	runtime/mspanset.go:273 +0xb6 fp=0x70000f060f08 sp=0x70000f060ed8 pc=0x70cfe16
runtime.finishsweep_m()
	runtime/mgcsweep.go:258 +0x93 fp=0x70000f060f48 sp=0x70000f060f08 pc=0x70c0b33
...
runtime.gopark(0x1a329bc18003?, 0x0?, 0x0?, 0x0?, 0x0?)
	runtime/proc.go:462 +0xce fp=0x3f3368ff4740 sp=0x3f3368ff4720 pc=0x710bb0e
runtime.gcBgMarkWorker(0x3f3369092150)
	runtime/mgc.go:1791 +0xeb fp=0x3f3368ff47c8 sp=0x3f3368ff4740 pc=0x70b4b6b
runtime.gcBgMarkStartWorkers.gowrap1()
	runtime/mgc.go:1695 +0x17 fp=0x3f3368ff47e0 sp=0x3f3368ff47c8 pc=0x70b4a57
runtime.goexit({})
	runtime/asm_amd64.s:1776 +0x1 fp=0x3f3368ff47e8 sp=0x3f3368ff47e0 pc=0x7112f21
created by runtime.gcBgMarkStartWorkers in goroutine 1
	runtime/mgc.go:1695 +0x105

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/tools/gopls/internal/golang.test" && test == ""

2025-12-08 14:39 x_tools-go1.26-darwin-amd64_12 tools@748477b5 release-branch.go1.26@6b694d01 x/tools/gopls/internal/golang.test (log)

# golang.org/x/tools/gopls/internal/golang.test
fatal error: span set block with unpopped elements found in reset

runtime stack:
runtime.throw({0x737979b?, 0x103d9000?})
	runtime/panic.go:1229 +0x48 fp=0x70000f060ed8 sp=0x70000f060ea8 pc=0x710b9e8
runtime.(*spanSet).reset(0x768ff90?)
	runtime/mspanset.go:273 +0xb6 fp=0x70000f060f08 sp=0x70000f060ed8 pc=0x70cfe16
runtime.finishsweep_m()
	runtime/mgcsweep.go:258 +0x93 fp=0x70000f060f48 sp=0x70000f060f08 pc=0x70c0b33
...
runtime.gopark(0x1a329bc18003?, 0x0?, 0x0?, 0x0?, 0x0?)
	runtime/proc.go:462 +0xce fp=0x3f3368ff4740 sp=0x3f3368ff4720 pc=0x710bb0e
runtime.gcBgMarkWorker(0x3f3369092150)
	runtime/mgc.go:1791 +0xeb fp=0x3f3368ff47c8 sp=0x3f3368ff4740 pc=0x70b4b6b
runtime.gcBgMarkStartWorkers.gowrap1()
	runtime/mgc.go:1695 +0x17 fp=0x3f3368ff47e0 sp=0x3f3368ff47c8 pc=0x70b4a57
runtime.goexit({})
	runtime/asm_amd64.s:1776 +0x1 fp=0x3f3368ff47e8 sp=0x3f3368ff47e0 pc=0x7112f21
created by runtime.gcBgMarkStartWorkers in goroutine 1
	runtime/mgc.go:1695 +0x105

— watchflakes