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griesemer opened this issue Jun 1, 2018 · 5 comments
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gccgo: internal compiler error with cyclic function declaration (esoteric) #25680

griesemer opened this issue Jun 1, 2018 · 5 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Gccgo

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@griesemer
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With

$ gccgo --version
gccgo (google-gccgo-257955) 8.0.1 20180223 (experimental)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

compiling the following program:

$ cat x.go
package main

func g() [g()[0]]int { panic(0) }

func main() {
}

leads to an internal compiler error:

$ gccgo x.go
gccgo: internal compiler error: Segmentation fault signal terminated program go1
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://go.ext.google.com/go/> for instructions.

cc: @thanm
@griesemer griesemer added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jun 1, 2018
@griesemer griesemer added this to the Gccgo milestone Jun 1, 2018
@ianlancetaylor
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I hope that program is not valid Go.

@griesemer
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I don't think it is. But it probably shouldn't crash. But certainly not important in any case. Just reporting another test case for the cycle test suite...

@AlbinoGeek AlbinoGeek mentioned this issue Jun 1, 2018
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This was referenced Jun 1, 2018
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@thanm thanm assigned thanm and unassigned ianlancetaylor Jun 1, 2018
@thanm
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thanm commented Jun 1, 2018

Related to #25315, #25677, #25299. Should be able to fix them together (at least for gccgo).

@deanveloper
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I hope that program is not valid Go.

It isn't. Array lengths are defined as follows:

The length is part of the array's type; it must evaluate to a non-negative constant representable by a value of type int.

Since [g()[0]]int is an array, and g()[0] is not a constant this is not valid Go.

@gopherbot
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Change https://golang.org/cl/115796 mentions this issue: compiler: fix crashes on cyclic var/type references

hubot pushed a commit to gcc-mirror/gcc that referenced this issue Jun 4, 2018
compiler: fix crashes on cyclic var/type references
54934d7 
    
    This patch fixes type traversal to avoid compiler crashes for test
    cases where a type T includes an expression that refers back to the
    type without actually explicitly mentioning T. Examples include
    
      var x [uintptr(unsafe.Sizeof(&x))]byte
      var a [len(a)]int
    
    The fix involves expanding the set of types that the traversal code
    "remembers" (to avoid cycles) to include array types, and introducing an
    additional guard in Builtin_call_expression::do_is_constant to catch
    cyclic type constructs.
    
    Fixes golang/go#25299
    Fixes golang/go#25679
    Fixes golang/go#25315
    Fixes golang/go#25680
    
    Reviewed-on: https://go-review.googlesource.com/115796


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@261168 138bc75d-0d04-0410-961f-82ee72b054a4
@golang golang locked and limited conversation to collaborators Jun 4, 2019
asiekierka pushed a commit to WonderfulToolchain/gcc-ia16 that referenced this issue May 16, 2022
compiler: fix crashes on cyclic var/type references
f0ebf6e 
    
    This patch fixes type traversal to avoid compiler crashes for test
    cases where a type T includes an expression that refers back to the
    type without actually explicitly mentioning T. Examples include
    
      var x [uintptr(unsafe.Sizeof(&x))]byte
      var a [len(a)]int
    
    The fix involves expanding the set of types that the traversal code
    "remembers" (to avoid cycles) to include array types, and introducing an
    additional guard in Builtin_call_expression::do_is_constant to catch
    cyclic type constructs.
    
    Fixes golang/go#25299
    Fixes golang/go#25679
    Fixes golang/go#25315
    Fixes golang/go#25680
    
    Reviewed-on: https://go-review.googlesource.com/115796

From-SVN: r261168
@rsc rsc unassigned thanm Jun 23, 2022
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