Golang x/tools/internal/mcp/examples/sse: unrecognized failures

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

Issue created automatically to collect these failures.

Example (log):

FAIL    golang.org/x/tools/internal/mcp/examples/sse [build failed]
# golang.org/x/tools/internal/mcp/jsonschema
runtime: pointer 0xc002349e80 to unused region of span span.base()=0xc002348000 span.limit=0xc002149f80 span.state=1
runtime: found in object at *(0xc001bc0d20+0x48)
object=0xc001bc0d20 s.base()=0xc001bc0000 s.limit=0xc001bc1f40 s.spanclass=14 s.elemsize=80 s.state=mSpanInUse
 *(object+0) = 0x13609000000408
 *(object+8) = 0x116
 *(object+16) = 0x0
 *(object+24) = 0x0
 *(object+32) = 0x0
...
fatal error: found bad pointer in Go heap (incorrect use of unsafe or cgo?)

runtime stack:
runtime.throw({0x11471b32?, 0x6?})
    runtime/panic.go:1094 +0x48 fp=0x700007284d70 sp=0x700007284d40 pc=0x10acf4e8
runtime.badPointer(0x12e477c8, 0xc002349e80, 0xc001bc0d20, 0x48)
    runtime/mbitmap.go:1292 +0x165 fp=0x700007284dc0 sp=0x700007284d70 pc=0x10a66f85
runtime.findObject(...)
    runtime/mbitmap.go:1344
runtime.scanobject(0xc000041850?, 0xc000041850)
...
runtime.gopark(...)
    runtime/proc.go:460
runtime.gcBgMarkWorker(0xc002d69dc0)
    runtime/mgc.go:1463 +0x196 fp=0xc003ec37c8 sp=0xc003ec3740 pc=0x10a70b96
runtime.gcBgMarkStartWorkers.gowrap1()
    runtime/mgc.go:1373 +0x25 fp=0xc003ec37e0 sp=0xc003ec37c8 pc=0x10a709a5
runtime.goexit({})
    runtime/asm_amd64.s:1693 +0x1 fp=0xc003ec37e8 sp=0xc003ec37e0 pc=0x10ad7521
created by runtime.gcBgMarkStartWorkers in goroutine 215
    runtime/mgc.go:1373 +0x105

— watchflakes

Comment From: gopherbot

Found new dashboard test flakes for:

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

2025-07-09 19:52 x_tools-gotip-darwin-amd64_12 tools@63f81c9f go@67c17044 x/tools/internal/mcp/examples/sse (log)

FAIL golang.org/x/tools/internal/mcp/examples/sse [build failed] # golang.org/x/tools/internal/mcp/jsonschema runtime: pointer 0xc002349e80 to unused region of span span.base()=0xc002348000 span.limit=0xc002149f80 span.state=1 runtime: found in object at *(0xc001bc0d20+0x48) object=0xc001bc0d20 s.base()=0xc001bc0000 s.limit=0xc001bc1f40 s.spanclass=14 s.elemsize=80 s.state=mSpanInUse *(object+0) = 0x13609000000408 *(object+8) = 0x116 *(object+16) = 0x0 *(object+24) = 0x0 *(object+32) = 0x0 ... fatal error: found bad pointer in Go heap (incorrect use of unsafe or cgo?) runtime stack: runtime.throw({0x11471b32?, 0x6?}) runtime/panic.go:1094 +0x48 fp=0x700007284d70 sp=0x700007284d40 pc=0x10acf4e8 runtime.badPointer(0x12e477c8, 0xc002349e80, 0xc001bc0d20, 0x48) runtime/mbitmap.go:1292 +0x165 fp=0x700007284dc0 sp=0x700007284d70 pc=0x10a66f85 runtime.findObject(...) runtime/mbitmap.go:1344 runtime.scanobject(0xc000041850?, 0xc000041850) ... runtime.gopark(...) runtime/proc.go:460 runtime.gcBgMarkWorker(0xc002d69dc0) runtime/mgc.go:1463 +0x196 fp=0xc003ec37c8 sp=0xc003ec3740 pc=0x10a70b96 runtime.gcBgMarkStartWorkers.gowrap1() runtime/mgc.go:1373 +0x25 fp=0xc003ec37e0 sp=0xc003ec37c8 pc=0x10a709a5 runtime.goexit({}) runtime/asm_amd64.s:1693 +0x1 fp=0xc003ec37e8 sp=0xc003ec37e0 pc=0x10ad7521 created by runtime.gcBgMarkStartWorkers in goroutine 215 runtime/mgc.go:1373 +0x105

— watchflakes

Comment From: cherrymui

Dup of #74552.