cmd/compile: type assertion panic in types2.(*Checker).instantiatedType (1.24rc1)

[prattmic]

#!stacks
"cmd/compile/internal/types2.(*Checker).instantiatedType:+38"

Issue created by stacks.

This stack SiR3fA was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:+1
• cmd/compile/internal/types2.(*Checker).typ:=152
• cmd/compile/internal/types2.(*Checker).compositeLit:+17
• cmd/compile/internal/types2.(*Checker).exprInternal:+38
• cmd/compile/internal/types2.(*Checker).rawExpr:+10
• cmd/compile/internal/types2.(*Checker).genericExpr:+1

cmd/compile@go1.24rc1 go1.24rc1 darwin/arm64 (12)

This crash is a type assertion failure at https://cs.opensource.google/go/go/+/refs/tags/go1.24rc1:src/cmd/compile/internal/types2/typexpr.go;l=480;drc=b631b8e674195f6cdeca363ccb01279f14b10f13

inst := check.instance(x.Pos(), gtyp, targs, nil, check.context()).(genericType)

This type assertion is new in 1.24 (https://go.dev/cl/615275), so I am tentatively marking this a release blocker.

cc @griesemer @golang/compiler
Dups: 5UTERQ DeGb4g 9o-X9Q LUaCHQ 3uw3Qw NKGM6Q

[prattmic]

This stack 5UTERQ was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:+1
• cmd/compile/internal/types2.(*Checker).typ:=152
• cmd/compile/internal/types2.(*Checker).bound:+12
• cmd/compile/internal/types2.(*Checker).collectTypeParams:+38
• cmd/compile/internal/types2.(*Checker).typeDecl:+83
• cmd/compile/internal/types2.(*Checker).objDecl:+139

cmd/compile@go1.24rc1 go1.24rc1 linux/amd64 (10)

This stack DeGb4g was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:+1
• cmd/compile/internal/types2.(*Checker).typeDecl:+55
• cmd/compile/internal/types2.(*Checker).objDecl:+139
• cmd/compile/internal/types2.(*Checker).packageObjects:=691
• cmd/compile/internal/types2.(*Checker).checkFiles:+29
• cmd/compile/internal/types2.(*Checker).Files:+13

cmd/compile@go1.24rc1 go1.24rc1 linux/amd64 (1)

This stack 9o-X9Q was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:+1
• cmd/compile/internal/types2.(*Checker).typ:=152
• cmd/compile/internal/types2.(*Checker).compositeLit:+17
• cmd/compile/internal/types2.(*Checker).exprInternal:+38
• cmd/compile/internal/types2.(*Checker).rawExpr:+10
• cmd/compile/internal/types2.(*Checker).expr:+1

cmd/compile@go1.24rc1 go1.24rc1 darwin/arm64 (9)

This stack LUaCHQ was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:=195
• cmd/compile/internal/types2.(*Checker).varType:+1
• cmd/compile/internal/types2.(*Checker).collectParams:=351
• cmd/compile/internal/types2.(*Checker).funcType:+23
• cmd/compile/internal/types2.(*Checker).funcDecl:=759
• cmd/compile/internal/types2.(*Checker).objDecl:+143

cmd/compile@go1.24rc1 go1.24rc1 darwin/arm64 (5)

This stack 3uw3Qw was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:=195
• cmd/compile/internal/types2.(*Checker).varType:+1
• cmd/compile/internal/types2.(*Checker).typeList:+3
• cmd/compile/internal/types2.(*Checker).instantiatedType:+30
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:=195

cmd/compile@go1.24rc1 go1.24rc1 linux/amd64 (6)

This stack NKGM6Q was reported by telemetry:

• compile/bug
• cmd/compile/internal/base.FatalfAt:+3
• cmd/compile/internal/base.Fatalf:=195
• cmd/compile/internal/gc.handlePanic:+7
• runtime.gopanic:+50
• cmd/compile/internal/types2.(*Checker).handleBailout:+7
• runtime.gopanic:+50
• runtime.getitab:=102
• runtime.typeAssert:+7
• cmd/compile/internal/types2.(*Checker).instantiatedType:+38
• cmd/compile/internal/types2.(*Checker).typInternal:+60
• cmd/compile/internal/types2.(*Checker).definedType:+1
• cmd/compile/internal/types2.(*Checker).typ:=152
• cmd/compile/internal/types2.(*Checker).bound:+12
• cmd/compile/internal/types2.(*Checker).collectTypeParams:+38
• cmd/compile/internal/types2.(*Checker).funcType:+19
• cmd/compile/internal/types2.(*Checker).funcDecl:=759

cmd/compile@go1.24rc1 go1.24rc1 linux/amd64 (2)

[griesemer]

I believe this is a dup of #71198 for which the fix will be submitted shortly: CL 641857.

[gabyhelp]

Related Issues

• go/types: failed genericType assertion in Checker.instantiatedType #71198
• cmd/compile: bug in cmd/compile/internal/types2.setDefType #71010
• cmd/compile: bug in cmd/compile/internal/importer.(*pkgReader).objIdx.func1 #70996
• cmd/compile/internal/types2: panic when type function selector is not instantiated #48048 (closed)
• cmd/compile: bug in cmd/compile/internal/importer.(*reader).typInfo #71012
• cmd/compile/internal/types2: unify.go:449: assertion failed, panic #67872 (closed)
• go/types: panic("t.fromRHS = %s, typ = %s") in setDefType #71029
• cmd/go2go: Panic in type checker #42522 (closed)
• cmd/compile: internal compiler error: panic: builtins.go: assertion failed #61486 (closed)
• go/types, types2: crash in typesSummary (which assumes well-typedness) #70526 (closed)

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

[prattmic]

Thanks!