[ICE] Combination of concept, dotOperators & static leads to internal error

[Vindaar]

Description

This is a highly reduced case of an issue I encountered because a bug in a macro meant the wrong code was generated, leaving me with an internal error.

edit: See metagn's version in the first response for a smaller example.

import std / macros
macro matchMe*(x: typed): untyped =
  discard x.getTypeImpl 

type
  SomeUnit* = concept x
    matchMe(x)

template `.`*[T: SomeUnit](x: T): untyped =  discard

proc foo*() = discard

type
  ElementRT* = object
  Element*[Z: static int] = ElementRT # this version is needed, even though we don't use it

let ar = ElementRT()
discard ar.mutate(foo())

Nim Version

Nim Compiler Version 1.7.3 [Linux: amd64]
Compiled at 2022-12-02
Copyright (c) 2006-2022 by Andreas Rumpf

git hash: 10b6e4f
active boot switches: -d:release -d:danger

Current Output

SIGSEGV: Illegal storage access. (Attempt to read from nil?)
zsh: segmentation fault  nim c /t/bug3

Expected Output

Something along the lines of: Error: expression 'foo()' has no type (or is ambiguous)

Possible Solution

Running koch temp on it yields:

/home/basti/src/nim/nim_git_repo/compiler/nim.nim(153) nim
/home/basti/src/nim/nim_git_repo/compiler/nim.nim(108) handleCmdLine
/home/basti/src/nim/nim_git_repo/compiler/main.nim(285) mainCommand
/home/basti/src/nim/nim_git_repo/compiler/main.nim(254) compileToBackend
/home/basti/src/nim/nim_git_repo/compiler/main.nim(110) commandCompileToC
/home/basti/src/nim/nim_git_repo/compiler/modules.nim(136) compileProject
/home/basti/src/nim/nim_git_repo/compiler/modules.nim(56) compileModule
/home/basti/src/nim/nim_git_repo/compiler/passes.nim(186) processModule
/home/basti/src/nim/nim_git_repo/compiler/passes.nim(79) processTopLevelStmt
/home/basti/src/nim/nim_git_repo/compiler/sem.nim(783) myProcess
/home/basti/src/nim/nim_git_repo/compiler/sem.nim(751) semStmtAndGenerateGenerics
/home/basti/src/nim/nim_git_repo/compiler/semstmts.nim(2520) semStmt
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(1090) semExprNoType
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3122) semExpr
/home/basti/src/nim/nim_git_repo/lib/system.nim(910) semStmtList
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3128) semExpr
/home/basti/src/nim/nim_git_repo/compiler/semstmts.nim(45) semDiscard
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(87) semExprWithType
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(71) semExprCheck
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3036) semExpr
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(983) semIndirectOp
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3028) semExpr
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(1071) semDirectOp
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(908) semOverloadedCallAnalyseEffects
/home/basti/src/nim/nim_git_repo/compiler/semcall.nim(574) semOverloadedCall
/home/basti/src/nim/nim_git_repo/compiler/semcall.nim(386) resolveOverloads
/home/basti/src/nim/nim_git_repo/compiler/semcall.nim(95) pickBestCandidate
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(2586) matches
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(2520) matchesAux
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(2227) paramTypesMatch
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(2068) paramTypesMatchAux
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(1720) typeRel
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(1644) typeRel
/home/basti/src/nim/nim_git_repo/compiler/sigmatch.nim(752) matchUserTypeClass
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(2209) tryExpr
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3122) semExpr
/home/basti/src/nim/nim_git_repo/lib/system.nim(910) semStmtList
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(3034) semExpr
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(1072) semDirectOp
/home/basti/src/nim/nim_git_repo/compiler/semexprs.nim(953) afterCallActions
/home/basti/src/nim/nim_git_repo/compiler/sem.nim(500) semMacroExpr
/home/basti/src/nim/nim_git_repo/compiler/vm.nim(2471) evalMacroCall
/home/basti/src/nim/nim_git_repo/compiler/vm.nim(1813) rawExecute
/home/basti/src/nim/nim_git_repo/compiler/vmdeps.nim(323) opMapTypeImplToAst
/home/basti/src/nim/nim_git_repo/compiler/vmdeps.nim(150) mapTypeToAstX
/home/basti/src/nim/nim_git_repo/compiler/vmdeps.nim(172) mapTypeToAstX
/home/basti/src/nim/nim_git_repo/lib/system/fatal.nim(54) sysFatal
Error: unhandled exception: field 'sons' is not accessible for type 'TNode' using 'kind = 3' [FieldDefect]
FAILURE

checking the source of the problem indicates the following line (https://github.com/nim-lang/Nim/blob/devel/compiler/vmdeps.nim#L170):

      result.add objectDef[0].copyTree  # copy object pragmas

so it accesses the first child of objectDef, which in this case is invalid. Extending the nkRefTy check above to:

      elif objectDef.kind == nkSym:
        objectDef = objectDef.sym.ast[2]

gives the correct compiler error in this case. But this is just me copying the logic from a few lines above for the case where the AST of the input symbol is itself a symbol. I suppose there is a cleaner solution?

Additional Information

No response

[metagn]

Minimized? Unsure if this is the same error

import std/macros

macro matchMe(x: typed): untyped =
  discard x.getTypeImpl

type
  ElementRT = object
  Element[Z] = ElementRT # this version is needed, even though we don't use it

let ar = ElementRT()
matchMe(ar)

For some reason this "generic alias impl AST replaces original type impl AST" situation feels familiar but I can't find a related issue.

[Vindaar]

Haha, after manically reducing the code from having to remove 3 big dependencies to reproduce it and keeping "one bit" from each made me miss the forest for the trees. :) Yeah, your code is the same issue!