cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) #51219

Karitham · 2022-02-16T11:25:12Z

What version of Go are you using (`go version`)?

❯ g version
go version devel go1.18-293ecd8 Tue Feb 15 22:54:38 2022 +0000 linux/amd64

Does this issue reproduce with the latest release?

1.18beta1, beta2 & gotip

What operating system and processor architecture are you using (`go env`)?

go env Output

❯ g env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/karitham/.cache/go-build"
GOENV="/home/karitham/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/karitham/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/karitham/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/karitham/sdk/gotip"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/karitham/sdk/gotip/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel go1.18-293ecd8 Tue Feb 15 22:54:38 2022 +0000"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/karitham/corde/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build4188918709=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Using type parameters, I get a compiler panic in an assignment.

I have tried extremely hard to provide a better program, but haven't managed to reproduce the bug easily on the playground.

See https://github.com/Karitham/corde/blob/error/compiler-panic/components/interactions.go#L148-L156 for the whole codebase with the log

What did you expect to see?

Either a compile error that makes sense, or my program building (most likely the second one, but I'm not familiar enough with generics yet to expect my code to be 100% valid)

What did you see instead?

Nonsensical error message and/or compiler panic

The text was updated successfully, but these errors were encountered:

dmitshur · 2022-02-16T13:48:53Z

CC @ianlancetaylor, @randall77.

randall77 · 2022-02-16T16:03:34Z

To reproduce:

$ git clone https://github.com/Karitham/corde
$ cd corde
$ git checkout 1848bb7405f089e2e68952b015278f94afe3f053
$ cd components
$ go build
# github.com/Karitham/corde/components
./interactions.go:152:11: cannot use bt.Data (variable of type JsonRaw) as type JsonRaw in assignment

I think there's some confusion as to what JsonRaw is. Inside UnmarshalJSON, JsonRaw is a type parameter. But in the definition of _basicT, JsonRaw is a concrete type (a []byte, defined in json.go).
So the error is correct, it is just confusing because you have two different types with the same name.

Same as if you did:

package main

type T int

var x T

func f() {
	type T float64
	var y T
	x = y
}

tmp1.go:10:4: cannot use y (type T) as type T in assignment

Closing, as this is not a bug. Maybe there would be ways to improve the error messages (include definition line of the type name when it appears more than once in the error message?) but this is currently working as expected.

Karitham · 2022-02-16T16:27:50Z

Have you tried removing the assignment, though?

Just to be clear, if you do remove the assignment you get a compiler internal error, which is for sure unexpected

It's also where an issue comes in, JsonRaw isn't defined as a type & a variable, it's used as a type in the Type Parameter on the receiver, but nowhere is it defined by something else.

I'm not sure why the type parameter on the receiver would turn out to be its own new type identifier when it shouldn't be?
Why would I not be able to assign to a variable of that type inside the function, especially since both underlying types are exactly the same? I can't cast either? Is this a lost cause?

It makes it literally impossible to make specific implementations of methods on structures with type parameters?

Karitham · 2022-02-16T16:40:58Z

I should have been more clear earlier, my mistake; I tried diving into the problem but it ended up like an X/Y problem

To reproduce the error building & the error message

git clone https://github.com/Karitham/corde
cd corde
git checkout ae8ae03a3401df2f1a6a365e81742bf90acfaf94
go test ./...

@randall77

Full stack trace

❯ g test
# github.com/Karitham/corde [github.com/Karitham/corde.test]
./router.go:91:11: internal compiler error: unexpected expr: COMPLIT Mux{...}

goroutine 1 [running]:
runtime/debug.Stack()
        /home/karitham/sdk/gotip/src/runtime/debug/stack.go:24 +0x65
cmd/compile/internal/base.FatalfAt({0xd4ca71?, 0x0?}, {0xd2fd6a, 0x16}, {0xc0000e90a8, 0x2, 0x2})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/base/print.go:227 +0x1d7
cmd/compile/internal/base.Fatalf(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/base/print.go:196
cmd/compile/internal/escape.(*escape).exprSkipInit(0xc001265e60, {0xc001272700?, 0xc0000e91a8?, 0x0?, 0x0?}, {0xe98e20, 0xc000de3e80?})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/expr.go:39 +0x1825
cmd/compile/internal/escape.(*escape).expr(0xc001272700?, {0xc001272700?, 0x0?, 0x0?, 0x30?}, {0xe98e20, 0xc000de3e80})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/expr.go:20 +0xad
cmd/compile/internal/escape.(*escape).exprSkipInit(0xc001265e60, {0xc001272700?, 0x6f4368?, 0x0?, 0x90?}, {0xe98330, 0xc0004ec320?})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/expr.go:64 +0xbed
cmd/compile/internal/escape.(*escape).expr(0xc001272700?, {0xc001272700?, 0x0?, 0x0?, 0x50?}, {0xe98330, 0xc0004ec320})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/expr.go:20 +0xad
cmd/compile/internal/escape.(*escape).assignList(0xc001265e60, {0xc0000e96b8, 0x1, 0xc0004e0a90?}, {0xc0000e96a8, 0x1, 0xc001265e60?}, {0xd1d7d2, 0x6}, {0xe98650, ...})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/assign.go:93 +0x3d6
cmd/compile/internal/escape.(*escape).stmt(0xc001265e60, {0xe98650, 0xc0004ec370?})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/stmt.go:143 +0x3b8
cmd/compile/internal/escape.(*escape).stmts(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/stmt.go:190
cmd/compile/internal/escape.(*escape).block(0xc001265e60?, {0xc000696e00?, 0x3?, 0xc0005b6a20?})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/stmt.go:197 +0x72
cmd/compile/internal/escape.(*batch).walkFunc(0xc0005b6a20, 0xc000d9c160)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/escape.go:227 +0xe5
cmd/compile/internal/escape.Batch({0xc001265e28?, 0x2, 0x3}, 0x0?)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/escape.go:143 +0x228
cmd/compile/internal/ir.(*bottomUpVisitor).visit(0xc00124b7d0, 0xc000d9c160)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/scc.go:127 +0x2f0
cmd/compile/internal/ir.(*bottomUpVisitor).visit.func1({0xe99398?, 0xc000d9c160?})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/scc.go:81 +0x45
cmd/compile/internal/ir.(*bottomUpVisitor).visit.func2({0xe9a018, 0xc000d8ba00})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/scc.go:91 +0x7e
cmd/compile/internal/ir.Visit.func1({0xe9a018, 0xc000d8ba00})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:105 +0x30
cmd/compile/internal/ir.(*CallExpr).doChildren(0xc000cd6ea0, 0xc00126ed38)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:260 +0x56
cmd/compile/internal/ir.DoChildren(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:94
cmd/compile/internal/ir.Visit.func1({0xe98a38, 0xc000cd6ea0})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:106 +0x57
cmd/compile/internal/ir.(*AssignStmt).doChildren(0xc000d82640, 0xc00126ed38)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:152 +0x7c
cmd/compile/internal/ir.DoChildren(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:94
cmd/compile/internal/ir.Visit.func1({0xe98650, 0xc000d82640})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:106 +0x57
cmd/compile/internal/ir.doNodes(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/node_gen.go:1512
cmd/compile/internal/ir.(*Func).doChildren(0xe99398?, 0xc00126ed38?)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/func.go:156 +0x6e
cmd/compile/internal/ir.DoChildren(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:94
cmd/compile/internal/ir.Visit.func1({0xe99398, 0xc000d9cdc0})
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:106 +0x57
cmd/compile/internal/ir.Visit({0xe99398, 0xc000d9cdc0}, 0xc001251c40)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/visit.go:108 +0xb8
cmd/compile/internal/ir.(*bottomUpVisitor).visit(0xc00124b7d0, 0xc000d9cdc0)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/scc.go:87 +0x1c8
cmd/compile/internal/ir.VisitFuncsBottomUp({0xc000517000, 0x87, 0x2?}, 0xd522c8)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/ir/scc.go:60 +0x105
cmd/compile/internal/escape.Funcs(...)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/escape/escape.go:118
cmd/compile/internal/gc.Main(0xd521b0)
        /home/karitham/sdk/gotip/src/cmd/compile/internal/gc/main.go:277 +0xe30
main.main()
        /home/karitham/sdk/gotip/src/cmd/compile/main.go:55 +0xdd

FAIL    github.com/Karitham/corde [build failed]

danscales · 2022-02-17T03:29:53Z

This relates to importing a complex recursive type. This issue only happens if the recursion happens through the type constraint. (In this program, the recursion actually goes through two different type constraints!)

I have the rough fix (small changes to the importers), but creating a minimized test case may take a while. I believe this is not a release-blocker, because of the unusual situation of recursion through the type constraint.

gopherbot · 2022-02-17T04:32:18Z

Change https://go.dev/cl/386335 mentions this issue: cmd/compile: fix importers to deal with recursion through type constraints

findleyr · 2022-02-18T18:25:14Z

I went to port this fix to x/tools/go/internal/gcimporter, and observed that it doesn't reproduce with the x/tools importer/exporter. @danscales mentioned something similar, that the error was not locally reproducible with the types2 importer. This suggests that there's some inconsistency across the types/import/export APIs. Reopening because we should nail down the root cause.

gopherbot · 2022-02-24T03:24:42Z

Change https://go.dev/cl/387814 mentions this issue: test: add new test case for 51219 that triggers the types2 issue

The existing test for 51219 didn't actually trigger the types2 issue - I hadn't been able to minimize the test case yet properly. This new test case issue51219b.go now does trigger the types2 issue (it's only slightly different). Updates #51219 Change-Id: Iaba8144b4702ff4fefec86c899b8acef127b10dc Reviewed-on: https://go-review.googlesource.com/c/go/+/387814 Trust: Dan Scales <danscales@google.com> Reviewed-by: Robert Findley <rfindley@google.com>

gopherbot · 2022-03-14T16:34:35Z

Change https://go.dev/cl/392475 mentions this issue: go/internal/gcimporter: guard against infinite recursion with recursive

gopherbot · 2022-03-14T18:34:35Z

Change https://go.dev/cl/392634 mentions this issue: gopls: update go.mod file for v0.8.1

For golang/go#51219 Change-Id: I62982e0ea084f78e81ec5ea6d6a0b6a039941968 Reviewed-on: https://go-review.googlesource.com/c/tools/+/392634 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> gopls-CI: kokoro <noreply+kokoro@google.com> Reviewed-by: Suzy Mueller <suzmue@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org>

gopherbot · 2022-03-14T19:57:14Z

Change https://go.dev/cl/392734 mentions this issue: go/internal/gcimporter: add a test case for issue 51219

type parameters This is a partial port of CL 386335 to x/tools. I have not yet been able to reproduce the crash in a test. For golang/go#51219 Change-Id: I262e6a9dba936b18513ee5f11a2a72d4155d3833 Reviewed-on: https://go-review.googlesource.com/c/tools/+/392475 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com> gopls-CI: kokoro <noreply+kokoro@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>

gopherbot · 2022-03-15T14:34:55Z

Change https://go.dev/cl/392915 mentions this issue: gopls: update go.mod file to pick up CL 392914

For golang/go#51219 Change-Id: Ib60fc1f22ce9ff094bc87ec36ad9e2c07c422c6e Reviewed-on: https://go-review.googlesource.com/c/tools/+/392915 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> gopls-CI: kokoro <noreply+kokoro@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

dmitshur added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 16, 2022

dmitshur added this to the Go1.18 milestone Feb 16, 2022

bcmills changed the title ~~cmd/go: internal compiler error~~ cmd/compile: internal compiler error Feb 16, 2022

randall77 closed this as completed Feb 16, 2022

randall77 reopened this Feb 16, 2022

danscales self-assigned this Feb 17, 2022

danscales changed the title ~~cmd/compile: internal compiler error~~ cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) Feb 17, 2022

virtuald mentioned this issue Feb 17, 2022

cmd/compile: internal compiler error: invalid memory address or nil pointer dereference #51232

Closed

gopherbot closed this as completed in d35ed09 Feb 18, 2022

findleyr reopened this Feb 18, 2022

gopherbot closed this as completed in golang/tools@40370f8 Mar 14, 2022

findleyr mentioned this issue Apr 1, 2022

go/types, types2: improve API for setting type parameter constraints in importers #52104

Open

rsc unassigned danscales Jun 22, 2022

golang locked and limited conversation to collaborators Jun 22, 2023

gopherbot added the FrozenDueToAge label Jun 22, 2023

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cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) #51219

cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) #51219

Karitham commented Feb 16, 2022

dmitshur commented Feb 16, 2022

randall77 commented Feb 16, 2022

Karitham commented Feb 16, 2022 •

edited

Karitham commented Feb 16, 2022 •

edited

danscales commented Feb 17, 2022

gopherbot commented Feb 17, 2022

findleyr commented Feb 18, 2022

gopherbot commented Feb 24, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 15, 2022

cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) #51219

cmd/compile: internal compiler error importing a recursive type (recursive through a type constraint) #51219

Comments

Karitham commented Feb 16, 2022

What version of Go are you using (go version)?

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

What did you do?

What did you expect to see?

What did you see instead?

dmitshur commented Feb 16, 2022

randall77 commented Feb 16, 2022

Karitham commented Feb 16, 2022 • edited

Karitham commented Feb 16, 2022 • edited

danscales commented Feb 17, 2022

gopherbot commented Feb 17, 2022

findleyr commented Feb 18, 2022

gopherbot commented Feb 24, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 14, 2022

gopherbot commented Mar 15, 2022

What version of Go are you using (`go version`)?

What operating system and processor architecture are you using (`go env`)?

Karitham commented Feb 16, 2022 •

edited

Karitham commented Feb 16, 2022 •

edited