cmd/link: linker panic and relocation errors with complex generics inlining

[denisvmedia]

Go version

go version go1.25.1 windows/amd64 (the same applies to running on linux/amd64)

Output of go env in your module/workspace:

set AR=ar
set CC=gcc
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_ENABLED=0
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set CXX=g++
set GCCGO=gccgo
set GO111MODULE=
set GOAMD64=v1
set GOARCH=amd64
set GOAUTH=netrc
set GOBIN=
set GOCACHE=C:\Users\user\AppData\Local\go-build
set GOCACHEPROG=
set GODEBUG=
set GOENV=C:\Users\user\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFIPS140=off
set GOFLAGS=
set GOGCCFLAGS=-m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=C:\Users\user\AppData\Local\Temp\go-build1541654439=/tmp/go-build -gno-record-gcc-switches
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMOD=NUL
set GOMODCACHE=C:\Users\user\go\pkg\mod
set GONOPROXY=gitlab.galeracluster.com/lib/executor
set GONOSUMDB=gitlab.galeracluster.com/lib/executor
set GOOS=windows
set GOPATH=C:\Users\user\go
set GOPRIVATE=gitlab.galeracluster.com/lib/executor
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Users\user\scoop\apps\go\current
set GOSUMDB=sum.golang.org
set GOTELEMETRY=local
set GOTELEMETRYDIR=C:\Users\user\AppData\Roaming\go\telemetry
set GOTMPDIR=
set GOTOOLCHAIN=auto
set GOTOOLDIR=C:\Users\user\scoop\apps\go\current\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.25.1
set GOWORK=
set PKG_CONFIG=pkg-config

What did you do?

Tested a project using complex generic constraints with different third-party generic ordered map libraries. The project uses a generic registry pattern with constrained type parameters.

This PR contains the issue demo: denisvmedia/inventario#579

Issue is observed with go 1.25.1 (also with 1.25.0), but is NOT observed with go 1.24.7.

What did you see happen?

Error 1: Relocation Target Not Defined with github.com/wk8/go-ordered-map/v2:

# github.com/denisvmedia/inventario/backup/restore.test
github.com/denisvmedia/inventario/backup/restore_test.TestRestoreService_SecurityValidation_CrossUserAccess: relocation target github.com/wk8/go-ordered-map/v2.New[go.shape.string,go.shape.*github.com/denisvmedia/inventario/models.User] not defined
github.com/denisvmedia/inventario/backup/restore_test.TestRestoreService_SecurityValidation_CrossTenantAccess: relocation target github.com/wk8/go-ordered-map/v2.New[go.shape.string,go.shape.*github.com/denisvmedia/inventario/models.User] not defined
[... multiple similar errors for different test functions ...]
Compilation finished with exit code 1

Error2: Linker Panic with github.com/elliotchance/orderedmap/v3

# github.com/denisvmedia/inventario/backup/restore.test
panic: inlined function github.com/elliotchance/orderedmap/v3.NewOrderedMap[go.shape.string,go.shape.*github.com/denisvmedia/inventario/models.User] missing func info

goroutine 1 [running]:
cmd/link/internal/ld.genInlTreeSym(0xc00013e000, 0x88a6d?, {0xc00012a388, 0xc000100700, {0xc000cb7860, 0x340, 0x340}, {0x10, 0x14, 0x1f, ...}}, ...)
	cmd/link/internal/ld/pcln.go:212 +0x4b9
cmd/link/internal/ld.makeInlSyms(0xc00013e000, {0xc012fdc000, 0x49b9, 0x49b9?}, 0xc0125cde30)
	cmd/link/internal/ld/pcln.go:235 +0x21e
cmd/link/internal/ld.(*Link).pclntab(0xc00013e000, {0xc012f26000?, 0xc0000123a8?, 0x12?})
	cmd/link/internal/ld/pcln.go:839 +0x1ce
cmd/link/internal/ld.Main(_, {0x20, 0x20, 0x1, 0x7, 0x10, 0x0, {0xc00000a691, 0x1, 0x1}, ...})
	cmd/link/internal/ld/main.go:430 +0x185c
main.main()
	cmd/link/main.go:72 +0xddb

Analysis

This appears to be a systematic linker issue when handling complex generic type parameters across package boundaries. The issue manifests in two different ways with different third-party libraries, but both involve:

1. Complex generic constraints: P registry.PIDable[T] where PIDable itself has type parameters
2. Cross-package inlining/linking of generic functions from third-party libraries
3. The same problematic type signature: [go.shape.string,go.shape.*github.com/denisvmedia/inventario/models.User]

Pattern observed:

• With orderedmap/v3: Linker panic during inlining metadata generation
• With go-ordered-map/v2: Linker relocation target not defined error
• Both involve the same complex generic type instantiation
• Both occur when building/testing, not during normal compilation

Workaround

The same fix works for both errors: Adding //go:noinline to the problematic function prevents both the panic and relocation errors:

//go:noinline
func NewRegistry[T any, P registry.PIDable[T]]() *Registry[T, P] {
    return &Registry[T, P]{
        items: orderedmap.NewOrderedMap[string, P](), // or go-ordered-map/v2.New[string, P]()
        lock:  &sync.RWMutex{},
    }
}

This strongly suggests the root cause is the same: linker issues with inlining complex generic functions.

Reproduction Conditions

The issue appears to require specific conditions that make minimal reproduction difficult:

• Complex generic constraint hierarchies (T any, P SomeInterface[T])
• Cross-package boundaries
• Multiple instantiation sites
• Specific build/test contexts (in this case only go test triggers it)

What did you expect to see?

Successful test execution.

[gabyhelp]

Related Issues

• cmd/compile: go1.21rc2: relocation R_X86_64_PC32 out of range error due to inliner changes #61218 (closed)
• cmd/compile/internal/types2: panic when type function selector is not instantiated #48048 (closed)
• cmd/link: index out of range panic when linking program #47432 (closed)
• cmd/compile: miscompilation of generic code; "unreachable method called. linker bug?" fatal error at runtime #48047 (closed)
• cmd/compile: nil pointer dereference in the 1.18 compiler when dealing with generic types #50423 (closed)
• cmd/compile/internal: nil pointer using labels on a function using generics. #48462 (closed)
• cmd/go2go: A type alias that references a parameterized type in another package causes a panic #39792 (closed)
• cmd/compile: panic when importing package contains self-referential generic interface type #48306 (closed)
• cmd/compile/internal/types2: invalid recursive type not detected and panics #48096 (closed)
• cmd/compile/internal/types: types.Type.LinkString has collisions for anonymous struct types with blank fields #47087 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[fengyoulin]

Bisect points to this CL https://go.dev/cl/641955. @cuonglm

[gopherbot]

Change https://go.dev/cl/703655 mentions this issue: cmd/compile: relax reshaping condition for pointers

[cuonglm]

@gopherbot please backport this issue to go1.25, it causes crashing when building a valid generic code.

[gopherbot]

Change https://go.dev/cl/704095 mentions this issue: cmd/compile: prevent shapifying of pointer shape type

[gopherbot]

Backport issue(s) opened: #75480 (for 1.25).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.