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cmd/compile: assertion failure when building syntax package with gotypesalias enabled #66873

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griesemer opened this issue Apr 17, 2024 · 9 comments
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done.
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@griesemer
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griesemer commented Apr 17, 2024

To reproduce:

  1. make.bash at tip
  2. comment out cmd/compile/internal/noder/irgen.go:91 (i.e., don't call os.Setenv)
  3. go install cmd/compile
  4. go build cmd/compile/internal/syntax

$ go build cmd/compile/internal/syntax
# cmd/compile/internal/syntax
cmd/compile/internal/syntax/tokens.go:7:6: internal compiler error: assertion failed

goroutine 1 [running]:
runtime/debug.Stack()
./runtime/debug/stack.go:26 +0x5e
cmd/compile/internal/base.FatalfAt({0x1853a40?, 0xc0?}, {0x69dcafc, 0x10}, {0x0, 0x0, 0x0})
cmd/compile/internal/base/print.go:225 +0x1d7
cmd/compile/internal/base.Fatalf(...)
cmd/compile/internal/base/print.go:194
cmd/compile/internal/base.Assert(...)
cmd/compile/internal/base/print.go:237
cmd/compile/internal/noder.assert(...)
cmd/compile/internal/noder/stencil.go:15
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:430
cmd/compile/internal/noder.(*reader).typWrapped(0xc0018537c0, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x156
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*reader).param(0xc0018537c0)
cmd/compile/internal/noder/reader.go:622 +0x18d
cmd/compile/internal/noder.(*reader).method(0xc0018537c0, 0xc001853900)
cmd/compile/internal/noder/reader.go:1022 +0x7c
cmd/compile/internal/noder.(*pkgReader).objIdxMayFail(0xc000ad56c0, 0x25, {0x0, 0x0, 0x0}, {0x721b420, 0x0, 0x0}, 0x0)
cmd/compile/internal/noder/reader.go:816 +0xd76
cmd/compile/internal/noder.(*pkgReader).objIdx(...)
cmd/compile/internal/noder/reader.go:670
cmd/compile/internal/noder.(*pkgReader).objInstIdx(0xc000ad56c0, {0xffffffff?, {0x721b420?, 0xc000600008?, 0xc0018468f0?}}, 0xc0017f5790, 0x0)
cmd/compile/internal/noder/reader.go:662 +0x96
cmd/compile/internal/noder.(*reader).obj(0xc001853400)
cmd/compile/internal/noder/reader.go:634 +0x46
cmd/compile/internal/noder.(*reader).doTyp(0xc001853400)
cmd/compile/internal/noder/reader.go:500 +0x72
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc001853040, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*pkgReader).objIdxMayFail(0xc000ad56c0, 0x24, {0x0, 0x0, 0x0}, {0x721b420, 0x0, 0x0}, 0x0)
cmd/compile/internal/noder/reader.go:744 +0xca5
cmd/compile/internal/noder.(*pkgReader).objIdx(...)
cmd/compile/internal/noder/reader.go:670
cmd/compile/internal/noder.(*pkgReader).objInstIdx(0xc000ad56c0, {0xffffffff?, {0x721b420?, 0xc000ccea40?, 0x60c1056?}}, 0xc0017f56c0, 0x0)
cmd/compile/internal/noder/reader.go:662 +0x96
cmd/compile/internal/noder.(*reader).obj(0xc001852c80)
cmd/compile/internal/noder/reader.go:634 +0x46
cmd/compile/internal/noder.(*reader).doTyp(0xc001852c80)
cmd/compile/internal/noder/reader.go:500 +0x72
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc001852b40, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*reader).structType(0xc001852b40)
cmd/compile/internal/noder/reader.go:589 +0xad
cmd/compile/internal/noder.(*reader).doTyp(0xc001852b40)
cmd/compile/internal/noder/reader.go:522 +0x37f
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc0018528c0, 0x0)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*pkgReader).objIdxMayFail(0xc000ad56c0, 0x23, {0x0, 0x0, 0x0}, {0x721b420, 0x0, 0x0}, 0x0)
cmd/compile/internal/noder/reader.go:805 +0x53c
cmd/compile/internal/noder.(*pkgReader).objIdx(...)
cmd/compile/internal/noder/reader.go:670
cmd/compile/internal/noder.(*pkgReader).objInstIdx(0xc000ad56c0, {0xffffffff?, {0x721b420?, 0x39300000005?, 0x0?}}, 0xc0017f4dd0, 0x0)
cmd/compile/internal/noder/reader.go:662 +0x96
cmd/compile/internal/noder.(*reader).obj(0xc001852500)
cmd/compile/internal/noder/reader.go:634 +0x46
cmd/compile/internal/noder.(*reader).doTyp(0xc001852500)
cmd/compile/internal/noder/reader.go:500 +0x72
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc0018523c0, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*reader).doTyp(0xc0018523c0)
cmd/compile/internal/noder/reader.go:516 +0xdb
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc001852280, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*reader).doTyp(0xc001852280)
cmd/compile/internal/noder/reader.go:520 +0x297
cmd/compile/internal/noder.(*pkgReader).typIdx(...)
cmd/compile/internal/noder/reader.go:429
cmd/compile/internal/noder.(*reader).typWrapped(0xc001844140, 0x1)
cmd/compile/internal/noder/reader.go:388 +0x125
cmd/compile/internal/noder.(*reader).typ(...)
cmd/compile/internal/noder/reader.go:382
cmd/compile/internal/noder.(*reader).param(...)
cmd/compile/internal/noder/reader.go:622
cmd/compile/internal/noder.(*reader).params(0xc001844140)
cmd/compile/internal/noder/reader.go:615 +0xad
cmd/compile/internal/noder.(*reader).signature(0xc001844140, 0xc001848870)
cmd/compile/internal/noder/reader.go:603 +0x5c
cmd/compile/internal/noder.(*reader).method(0xc001844140, 0xc001844280)
cmd/compile/internal/noder/reader.go:1023 +0x94
cmd/compile/internal/noder.(*pkgReader).objIdxMayFail(0xc000ad56c0, 0xcd, {0x0, 0x0, 0x0}, {0x721b420, 0x0, 0x0}, 0x0)
cmd/compile/internal/noder/reader.go:816 +0xd76
cmd/compile/internal/noder.(*pkgReader).objIdx(...)
cmd/compile/internal/noder/reader.go:670
cmd/compile/internal/noder.(*pkgReader).objInstIdx(0xc000ad56c0, {0xccf628?, {0x721b420?, 0x610d669?, 0x8?}}, 0x0, 0x0)
cmd/compile/internal/noder/reader.go:662 +0x96
cmd/compile/internal/noder.(*reader).obj(0xc000fed400)
cmd/compile/internal/noder/reader.go:634 +0x46
cmd/compile/internal/noder.(*reader).pkgObjs(0xc000fed400, 0xc000000240)
cmd/compile/internal/noder/reader.go:3314 +0x9d
cmd/compile/internal/noder.(*reader).pkgDecls(0xc000fed400, 0xc000000240)
cmd/compile/internal/noder/reader.go:3303 +0x18f
cmd/compile/internal/noder.(*reader).pkgInit(0xc000fed400, 0xc00007a320?, 0xc000000240)
cmd/compile/internal/noder/reader.go:3209 +0xe5
cmd/compile/internal/noder.unified({0x0?, {0x0?, 0x0?}}, {0xc000158380?, 0x6b64b00?, 0x0?})
cmd/compile/internal/noder/unified.go:188 +0x17c
cmd/compile/internal/noder.LoadPackage({0xc000022358, 0x10, 0x12})
cmd/compile/internal/noder/noder.go:77 +0x43a
cmd/compile/internal/gc.Main(0x6c18470)
cmd/compile/internal/gc/main.go:197 +0xbbd
main.main()
cmd/compile/main.go:57 +0xf9

@griesemer griesemer added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Apr 17, 2024
@griesemer griesemer added this to the Go1.23 milestone Apr 17, 2024
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Apr 17, 2024
@griesemer
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@adonovan for visibility

@griesemer
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griesemer commented Apr 17, 2024

The package object being compiled is checkBranches (cmd/compile/internal/syntax/branches.go) and then as part of it, (*labelScope).enclosingTarget.

@griesemer
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Follo-up: With pending CL 579935 (which may eventually get submitted), to enable type alias nodes, set the new types2.Config.EnableAlias flag in irgen.go.

@gopherbot
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Change https://go.dev/cl/568455 mentions this issue: cmd/compile: add test case for using Alias types

@griesemer
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Simple reproducer:

package p

func f(A) {}

type T int

type A = T

func (A) m() {}

Compiling this package (go tool compile p.go) with types2.Config.EnableAlias enabled causes the assertion failure. Changing the order of the declarations avoids the failure.

@mdempsky any insights?

@cuonglm
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cuonglm commented May 13, 2024

See also my investigation here: #65893 (comment)

We should probably land CL https://go-review.googlesource.com/c/go/+/568455, so this is the only issue that track the problem.

@griesemer
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The type checker seems to be doing the right thing for the above program:

== packageObjects ==

testdata/manual.go:14:6:        -- checking type T (white, objPath = )
testdata/manual.go:14:8:        .  -- type int
testdata/manual.go:14:8:        .  => int // *Basic
testdata/manual.go:14:6:        => type T int (black)

testdata/manual.go:16:6:        -- checking type A (white, objPath = )
testdata/manual.go:16:10:       .  -- type T
testdata/manual.go:16:10:       .  => T (under = int) // *Named
testdata/manual.go:16:6:        => type A = T (black)

testdata/manual.go:12:6:        -- checking func f (white, objPath = )
testdata/manual.go:12:8:        .  -- type A
testdata/manual.go:12:8:        .  => A (under = int) // *Alias
testdata/manual.go:12:6:        => func f(A) (black)

testdata/manual.go:18:10:       -- checking func m (white, objPath = )
testdata/manual.go:18:7:        .  -- type A
testdata/manual.go:18:7:        .  => A (under = int) // *Alias
testdata/manual.go:18:10:       => func (A).m() (black)

== processDelayed ==
testdata/manual.go:14:6:        -- validType(T)
testdata/manual.go:14:6:        .  validType(T) nest , path 
testdata/manual.go:14:6:        .  .  validType(int) nest T, path T

testdata/manual.go:14:6:        -- verifying field uniqueness for T

testdata/manual.go:16:6:        -- validType(A)
testdata/manual.go:14:6:        .  validType(T) nest , path 
testdata/manual.go:14:6:        .  .  validType(int) nest T, path T

testdata/manual.go:12:8:        -- check var type A

testdata/manual.go:12:6:        -- func f
testdata/manual.go:12:11:       -- f: func(A)

testdata/manual.go:18:7:        -- check var type A

testdata/manual.go:18:7:        -- validate receiver var  A

testdata/manual.go:18:10:       -- func m
testdata/manual.go:18:14:       -- m: func()

@mdempsky
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I think types2 is behaving correctly. The issue is we don't have proper alias types in compiler IR, so the importer can't rely on them to break cycles.

We might have to do a two-phase initialization to ensure IR is constructed in the right order. Thinking about it.

@gopherbot
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Change https://go.dev/cl/585399 mentions this issue: cmd/compile/internal/noder: enable type aliases in type checker

@dmitshur dmitshur added NeedsFix The path to resolution is known, but the work has not been done. and removed NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels May 15, 2024
gopherbot pushed a commit that referenced this issue May 16, 2024
CL 579935 disabled usage of Alias types in the compiler, and tracks
the problem with issue #66873. The test case in #65893 passes now
with the current tip. This CL adds a test case to ensure there is no
regression once Alias types are enabled for the compiler.

Updates #66873
Fixes #65893

Change-Id: I51b51bb13ca59549bc5925dd95f73da40465556d
Reviewed-on: https://go-review.googlesource.com/c/go/+/568455
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
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