regression: compiler/vmgen.nim(354, 20) `false` leaking temporary 10 slotTempInt [AssertionError]

[zevv]

On latest devel, related to #12485

This snippet:

type

  thingKind = enum
    One

  Thing = object
    case op: thingKind
      of One:
        name: int

static:
  var g: seq[Thing]
  for i in g.items:
    if i.op == One:
      var i2 = i
      i2.name = 44

crashes the compiler with compiler/vmgen.nim(354, 20) false leaking temporary 10 slotTempInt [AssertionError]. Unfortunately this breaks NPeg for me on devel.

Full stack trace:

/home/ico/external/Nim/compiler/nim.nim(106) nim
/home/ico/external/Nim/compiler/nim.nim(83) handleCmdLine
/home/ico/external/Nim/compiler/cmdlinehelper.nim(98) loadConfigsAndRunMainCommand
/home/ico/external/Nim/compiler/main.nim(188) mainCommand
/home/ico/external/Nim/compiler/main.nim(92) commandCompileToC
/home/ico/external/Nim/compiler/modules.nim(144) compileProject
/home/ico/external/Nim/compiler/modules.nim(85) compileModule
/home/ico/external/Nim/compiler/passes.nim(216) processModule
/home/ico/external/Nim/compiler/passes.nim(86) processTopLevelStmt
/home/ico/external/Nim/compiler/sem.nim(601) myProcess
/home/ico/external/Nim/compiler/sem.nim(569) semStmtAndGenerateGenerics
/home/ico/external/Nim/compiler/semstmts.nim(2216) semStmt
/home/ico/external/Nim/compiler/semexprs.nim(987) semExprNoType
/home/ico/external/Nim/compiler/semexprs.nim(2775) semExpr
/home/ico/external/Nim/compiler/importer.nim(214) evalImport
/home/ico/external/Nim/compiler/importer.nim(184) impMod
/home/ico/external/Nim/compiler/importer.nim(156) myImportModule
/home/ico/external/Nim/compiler/modules.nim(99) importModule
/home/ico/external/Nim/compiler/modules.nim(85) compileModule
/home/ico/external/Nim/compiler/passes.nim(210) processModule
/home/ico/external/Nim/compiler/passes.nim(86) processTopLevelStmt
/home/ico/external/Nim/compiler/sem.nim(601) myProcess
/home/ico/external/Nim/compiler/sem.nim(569) semStmtAndGenerateGenerics
/home/ico/external/Nim/compiler/semstmts.nim(2216) semStmt
/home/ico/external/Nim/compiler/semexprs.nim(987) semExprNoType
/home/ico/external/Nim/compiler/semexprs.nim(2742) semExpr
/home/ico/external/Nim/compiler/semstmts.nim(2156) semStmtList
/home/ico/external/Nim/compiler/semexprs.nim(2639) semExpr
/home/ico/external/Nim/compiler/semexprs.nim(969) semDirectOp
/home/ico/external/Nim/compiler/semexprs.nim(861) afterCallActions
/home/ico/external/Nim/compiler/sem.nim(470) semMacroExpr
/home/ico/external/Nim/compiler/vm.nim(2158) evalMacroCall
/home/ico/external/Nim/compiler/vm.nim(1113) rawExecute
/home/ico/external/Nim/compiler/vm.nim(459) compile
/home/ico/external/Nim/compiler/vmgen.nim(2257) genProc
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2066) gen
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2053) gen
/home/ico/external/Nim/compiler/vmgen.nim(343) genBlock
/home/ico/external/Nim/compiler/vmgen.nim(2066) gen
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2066) gen
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2053) gen
/home/ico/external/Nim/compiler/vmgen.nim(343) genBlock
/home/ico/external/Nim/compiler/vmgen.nim(2066) gen
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2066) gen
/home/ico/external/Nim/compiler/vmgen.nim(286) gen
/home/ico/external/Nim/compiler/vmgen.nim(2053) gen
/home/ico/external/Nim/compiler/vmgen.nim(354) genBlock
/home/ico/external/Nim/lib/system/assertions.nim(27) failedAssertImpl
/home/ico/external/Nim/lib/system/assertions.nim(20) raiseAssert
/home/ico/external/Nim/lib/system/fatal.nim(39) sysFatal
Error: unhandled exception: /home/ico/external/Nim/compiler/vmgen.nim(354, 20) `false` leaking temporary 10 slotTempInt [AssertionError]

Nim Compiler Version 1.1.0 [Linux: amd64]
Compiled at 2019-10-28
Copyright (c) 2006-2019 by Andreas Rumpf

git hash: 44b1ecc287fec603a9f24995ce6401ad0d109c55
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