Nim crash; constant array of refs is not reported as an error

[Tormund]

Nim is crashing when I compile this code

    type SomeRefObj = ref object of RootObj
        someIntMember: int

    proc createSomeRefObj(v: int): SomeRefObj=
        result.new()
        result.someIntMember = v

    const compileTimeSeqOfRefObjs = @[createSomeRefObj(100500), createSomeRefObj(2)]

With this stack-trace:

nim.nim(121)             nim
nim.nim(77)              handleCmdLine
main.nim(163)            mainCommand
main.nim(74)             commandCompileToC
modules.nim(240)         compileProject
modules.nim(180)         compileModule
passes.nim(215)          processModule
passes.nim(135)          processTopLevelStmt
sem.nim(549)             myProcess
sem.nim(521)             semStmtAndGenerateGenerics
semstmts.nim(1790)       semStmt
semexprs.nim(812)        semExprNoType
semexprs.nim(2371)       semExpr
importer.nim(212)        evalImport
importer.nim(191)        impMod
importer.nim(177)        myImportModule
modules.nim(203)         importModule
modules.nim(180)         compileModule
passes.nim(215)          processModule
passes.nim(135)          processTopLevelStmt
cgen.nim(1297)           myProcess
ccgstmts.nim(1126)       genStmts
ccgexprs.nim(2086)       expr
ccgstmts.nim(1126)       genStmts
ccgexprs.nim(2109)       expr
ccgstmts.nim(274)        genConstStmt
cgen.nim(805)            requestConstImpl
ccgexprs.nim(2272)       genConstExpr
ccgexprs.nim(2245)       genConstSeq
ccgexprs.nim(2276)       genConstExpr
ccgexprs.nim(2225)       genConstObjConstr
ccgexprs.nim(2196)       getNullValueAux
SIGSEGV: Illegal storage access. (Attempt to read from nil?)

nim git revision: 2b8a1ce

[Parashurama]

The general issue here is that const values cannot be of ref type.
Try this:

type SomeRefObj = object of RootObj
    someIntMember: int
const compileTimeSeqOfRefObjs  = (ref SomeRefObj)() # this fail
const compileTimeSeqOfRefObjs  = (SomeRefObj)() # this works

You can certainly use ref types in procs used at compile time.

proc builder(x: int): int =
    let k = new(SomeRefObj)
    k.someIntMember = x
    result = k.someIntMember
const compileTimeSeqOfRefObjs = builder(3)

Obviously the compiler shouldn't be crashing in this case but rather report an error message like this:

 Error: invalid type for const: ref SomeRefObj

[genotrance]

No longer crashes on #head.

[data-man]

I confirm and can't close for some reason. ;-)

@dom96 what about a test-case?

[genotrance]

This needs to be reopened - it shouldn't compile and should error out instead. Araq also could get it to crash in another way.

type SomeRefObj = ref object of RootObj
    someIntMember: int

proc createSomeRefObj(v: int): SomeRefObj=
    result.new()
    result.someIntMember = v

const compileTimeSeqOfRefObjs = @[createSomeRefObj(100500), createSomeRefObj(2)]

for i in 0..1:
  echo compileTimeSeqOfRefObjs[i].someIntMember

[genotrance]

Full stack trace:

Hint: used config file 'c:\Users\gt\Desktop\dl\programming\nimdevel\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: temp [Processing]
Traceback (most recent call last)
nim.nim(133)             nim
nim.nim(97)              handleCmdLine
main.nim(162)            mainCommand
main.nim(73)             commandCompileToC
modules.nim(124)         compileProject
modules.nim(71)          compileModule
passes.nim(194)          processModule
passes.nim(103)          processTopLevelStmt
cgen.nim(1379)           myProcess
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2255)       expr
ccgstmts.nim(514)        genBlock
ccgexprs.nim(2257)       expr
ccgexprs.nim(2052)       genStmtList
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2257)       expr
ccgexprs.nim(2052)       genStmtList
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2257)       expr
ccgexprs.nim(2052)       genStmtList
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2255)       expr
ccgstmts.nim(514)        genBlock
ccgexprs.nim(2278)       expr
ccgstmts.nim(492)        genWhileStmt
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2257)       expr
ccgexprs.nim(2041)       genStmtList
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2257)       expr
ccgexprs.nim(2052)       genStmtList
ccgstmts.nim(1150)       genStmts
ccgexprs.nim(2221)       expr
ccgexprs.nim(1898)       genMagicExpr
ccgexprs.nim(1005)       genEcho
cgen.nim(491)            initLocExpr
ccgexprs.nim(2241)       expr
ccgexprs.nim(2017)       genArrayConstr
ccgexprs.nim(2227)       expr
ccgexprs.nim(1847)       genMagicExpr
ccgexprs.nim(1457)       genDollar
cgen.nim(491)            initLocExpr
ccgexprs.nim(2253)       expr
ccgexprs.nim(778)        genRecordField
ccgexprs.nim(740)        genRecordFieldAux
cgen.nim(491)            initLocExpr
ccgexprs.nim(2252)       expr
ccgexprs.nim(689)        genDeref
cgen.nim(496)            initLocExprSingleUse
ccgexprs.nim(2251)       expr
ccgexprs.nim(939)        genBracketExpr
ccgexprs.nim(913)        genSeqElem
cgen.nim(491)            initLocExpr
ccgexprs.nim(2170)       expr
ccgexprs.nim(2020)       genComplexConst
cgen.nim(870)            requestConstImpl
ccgexprs.nim(2476)       genConstExpr
ccgexprs.nim(2449)       genConstSeq
ccgexprs.nim(2489)       genConstExpr
ccgexprs.nim(2428)       genConstObjConstr
ccgexprs.nim(2416)       getNullValueAuxT
ccgexprs.nim(2380)       getNullValueAux
SIGSEGV: Illegal storage access. (Attempt to read from nil?)

[timotheecour]

note:

this doesn't crash:
echo compileTimeSeqOfRefObjs[0].someIntMember

this crashes:
for i in 0..1: echo compileTimeSeqOfRefObjs[i].someIntMember

so, should it be illegal, or not?