Skip to content

cmd/compile: crash when compiling function named "_" #29870

Closed
@alandonovan

Description

@alandonovan
$ go version
go version devel +cad6d1fef5 Mon Jan 21 23:31:09 2019 +0000 linux/amd64
$ cat test/test.go 
package test

import "log"

func a() {
        log.Println("%2F")
}
$ go build test
$ sed -i -e 's/func a/func _/' test/test.go
$ go build test
# test
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x60 pc=0xc4e259]

goroutine 50 [running]:
cmd/compile/internal/gc.emitStackObjects(0xc000538000, 0xc0005ea0e0)
        ~/goroot/src/cmd/compile/internal/gc/ssa.go:5057 +0x1c9
cmd/compile/internal/gc.genssa(0xc00053c000, 0xc0005ea0e0)
        ~/goroot/src/cmd/compile/internal/gc/ssa.go:5092 +0xe1
cmd/compile/internal/gc.compileSSA(0xc0000cc420, 0x1)
        ~/goroot/src/cmd/compile/internal/gc/pgen.go:301 +0x378
cmd/compile/internal/gc.compileFunctions.func2(0xc0004fcf60, 0xc0004fe1d0, 0x1)
        ~/goroot/src/cmd/compile/internal/gc/pgen.go:356 +0x49
created by cmd/compile/internal/gc.compileFunctions
        ~/goroot/src/cmd/compile/internal/gc/pgen.go:354 +0x129

Activity

added
NeedsInvestigationSomeone must examine and confirm this is a valid issue and not a duplicate of an existing one.
on Jan 22, 2019
bcmills

bcmills commented on Jan 22, 2019

@bcmills
Contributor
added this to the Go1.13 milestone on Jan 22, 2019
self-assigned this
on Jan 22, 2019
gopherbot

gopherbot commented on Jan 22, 2019

@gopherbot
Contributor

Change https://golang.org/cl/158845 mentions this issue: cmd/compile: don't bother compiling functions named "_"

randall77

randall77 commented on Jan 22, 2019

@randall77
Contributor

This was introduced as part of adding stack objects. Fix out for review.

Do we care about functions named "_"? Is there any legitimate use for them? If so, we should fix this in 1.12. If not, we can leave for 1.13.

bcmills

bcmills commented on Jan 22, 2019

@bcmills
Contributor

I could imagine someone using them to contain static assertions: that is, a function named _ that fails to compile if certain conditions (such as equality of sizes) are not met.

I don't know whether anyone does that in practice.

alandonovan

alandonovan commented on Jan 22, 2019

@alandonovan
ContributorAuthor

I could imagine someone using them to contain static assertions.

Exactly. They must be type-checked, but there's no need to generate code for them.

gopherbot

gopherbot commented on Jan 22, 2019

@gopherbot
Contributor

Change https://golang.org/cl/158820 mentions this issue: cmd/compile: don't bother compiling functions named "_"

randall77

randall77 commented on Jan 22, 2019

@randall77
Contributor

The latter CL is for 1.12. The former CL has more clean up in it and will go in for 1.13.

locked and limited conversation to collaborators on Feb 26, 2020
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    FrozenDueToAgeNeedsInvestigationSomeone must examine and confirm this is a valid issue and not a duplicate of an existing one.

    Type

    No type

    Projects

    No projects

    Relationships

    None yet

      Development

      No branches or pull requests

        Participants

        @eliasnaur@bcmills@randall77@alandonovan@gopherbot

        Issue actions

          cmd/compile: crash when compiling function named "_" · Issue #29870 · golang/go