Version 1.4.0 released

We are very proud to announce Nim version 1.4 after six months of continuous development! Other than version 1.0, this is probably the biggest Nim release yet and we’re very excited to release it!

It contains exactly 900 new commits which have not already been backported to our previous versions. There are several new features and standard library additions compared to 1.2. We tried to keep breaking changes to a minimum, but some bugfixes weren’t possible without making those necessary changes, and we feel that our users will benefit from them.

We would recommend to all of our users to upgrade and use version 1.4.

This release also includes the latest version of Nim’s package manager Nimble, v0.12.0, the changelog for which is available here.

Installing Nim 1.4

New users

Check out if the package manager of your OS already ships version 1.4 or install it as described here.

Existing users

If you have installed a previous version of Nim using choosenim, getting Nim 1.4 is as easy as:

$ choosenim update self
$ choosenim update stable

If you don’t have choosenim, you can follow the same install link as above.

Contributors to v1.4

Our contributors are amazing, and there are far too many to list here. Big thanks to all of you, we couldn’t have pulled off this release without you!

New features


A new reference counting algorithm called ARC was first shipped with Nim 1.2. If you haven’t watched it already, we recommend this video from NimConf 2020 where Araq explains details behind ARC and shows some benchmarks that illustrate the benefits.

As far as we know, ARC works with the complete standard library except for the current implementation of async, because that introduces cycles that ARC doesn’t deal with. There are other async implementations in development that don’t introduce cycles.

ORC is the existing ARC algorithm plus a cycle collector, and --gc:orc is our main new feature for this release! We recommend reading this introductory ARC/ORC post to get an idea about ARC/ORC’s advantages.

How to use ARC and ORC

If you haven’t used ARC already with Nim 1.2, all you have to do is to pass --gc:arc on the command line:

nim c -d:release --gc:arc myprogram.nim

For the majority of programs this is all it takes.

If your code uses cyclic data structures, or if you’re not sure if your code produces cycles, you need to use --gc:orc and not --gc:arc.

If you have an object that looks cyclic, but you know it isn’t, you can help ORC by marking it as {.acyclic.} in the following way:

  Node {.acyclic.} = ref object
    left, right: Node
    data: string

To read more about {.acyclic.} pragma, please check out the manual.

Known incompatibilities and gotchas


If you use system.deepCopy in your code, you need to enable it via --deepCopy:on on the command line. This is a band-aid and a better solution for this will arrive in the future.

The reason for this opt-in switch is that ARC and ORC do not use the old runtime type information (RTTI) that system.deepCopy is built upon. We’ve built ARC and ORC with embedded devices in mind where the overhead of the old RTTI has been reported to be unacceptable.

Order of declarations

The second gotcha people might encounter is the strict ordering requirement for custom destructors; this affects old code as well, because finalizers are mapped to destructors. For example:

  CustomObject = ref object
    p: ptr int

proc tricky() =
  # would use the default destructor
  var x: CustomObject

proc finalizer(x: CustomObject) =
  if x.p != nil:

proc newCustomObject(): CustomObject =
  new(result, finalizer)

This produces the following error message:

temp.nim(15, 6) Error: cannot bind another '=destroy' to: CustomObject:ObjectType;
previous declaration was constructed here implicitly: temp.nim(8, 7)

The reason is that only after the new(result, finalizer) call the compiler knows that it needs to generate a custom destructor for the CustomObject type, but when it compiled tricky the default destructor was used.

The solution is to move the proc tricky after the newCustomObject declaration:

  CustomObject = ref object
    p: ptr int

proc finalizer(x: CustomObject) =
  if x.p != nil:

proc newCustomObject(): CustomObject =
  new(result, finalizer)

proc tricky() =
  # uses the custom destructor
  var x: CustomObject

This is a current limitation that will be improved in future versions of the compiler.

Strict(er) functions

This is an experimental feature available via {.experimental: "strictFuncs".} pragma in your code or via the --experimental:strictFuncs switch.

It introduces a stricter definition of a “side effect”: If an object is reachable via a parameter that is not declared as a var parameter, any mutation to that object counts as a side effect.

Here is an example from the experimental manual:

{.experimental: "strictFuncs".}

  Node = ref object
    le, ri: Node
    data: string

func len(n: Node): int =
  # valid: len does not have side effects
  var it = n
  while it != nil:
    inc result
    it = it.ri

func mut(n: Node) =
  let m = n # is the statement that connected the mutation to the parameter = "yeah" # the mutation is here
  # Error: 'mut' can have side effects
  # an object reachable from 'n' is potentially mutated

For more details, please see Araq’s blog post.


Standard library additions and changes

  • Added some enhancements to std/jsonutils module.
    • Added a possibility to deserialize JSON arrays directly to HashSet and OrderedSet types and respectively to serialize those types to JSON arrays via jsonutils.fromJson and jsonutils.toJson procedures.
    • Added a possibility to deserialize JSON null objects to Nim option objects and respectively to serialize Nim option object to JSON object if isSome or to JSON null object if isNone via jsonutils.fromJson and jsonutils.toJson procedures.
    • Added a Joptions parameter to jsonutils.fromJson currently containing two boolean options allowExtraKeys and allowMissingKeys.
      • If allowExtraKeys is true Nim’s object to which the JSON is parsed is not required to have a field for every JSON key.
      • If allowMissingKeys is true Nim’s object to which JSON is parsed is allowed to have fields without corresponding JSON keys.
  • Added bindParams, bindParam to db_sqlite for binding parameters into a SqlPrepared statement.
  • Added tryInsert,insert procs to db_* libs which accept primary key column name.
  • Added xmltree.newVerbatimText support create style’s,script’s text.
  • uri module now implements RFC-2397.
  • Added DOM Parser to the dom module for the JavaScript target.
  • The default hash for Ordinal has changed to something more bit-scrambling. import hashes; proc hash(x: myInt): Hash = hashIdentity(x) recovers the old one in an instantiation context while -d:nimIntHash1 recovers it globally.
  • deques.peekFirst and deques.peekLast now have var Deque[T] -> var T overloads.
  • File handles created from high-level abstractions in the stdlib will no longer be inherited by child processes. In particular, these modules are affected: asyncdispatch, asyncnet, system, nativesockets, net and selectors.

    For asyncdispatch, asyncnet, net and nativesockets, an inheritable flag has been added to all procs that create sockets, allowing the user to control whether the resulting socket is inheritable. This flag is provided to ease the writing of multi-process servers, where sockets inheritance is desired.

    For a transition period, define nimInheritHandles to enable file handle inheritance by default. This flag does not affect the selectors module due to the differing semantics between operating systems.

    asyncdispatch.setInheritable, system.setInheritable and nativesockets.setInheritable are also introduced for setting file handle or socket inheritance. Not all platforms have these procs defined.

  • The file descriptors created for internal bookkeeping by ioselector_kqueue and ioselector_epoll will no longer be leaked to child processes.

  • strutils.formatFloat with precision = 0 has been restored to the version 1 behaviour that produces a trailing dot, e.g. formatFloat(3.14159, precision = 0) is now 3., not 3.
  • Added commonPrefixLen to critbits.

  • relativePath(rel, abs) and relativePath(abs, rel) used to silently give wrong results (see #13222); instead they now use getCurrentDir to resolve those cases, and this can now throw in edge cases where getCurrentDir throws. relativePath also now works for js with -d:nodejs.

  • JavaScript and NimScript standard library changes: streams.StringStream is now supported in JavaScript, with the limitation that any buffer pointers used must be castable to ptr string, any incompatible pointer type will not work. The lexbase and streams modules used to fail to compile on NimScript due to a bug, but this has been fixed.

    The following modules now compile on both JS and NimScript: parsecsv, parsecfg, parsesql, xmlparser, htmlparser and ropes. Additionally supported for JS is cstrutils.startsWith and cstrutils.endsWith, for NimScript: json, parsejson, strtabs and unidecode.

  • Added streams.readStr and streams.peekStr overloads to accept an existing string to modify, which avoids memory allocations, similar to streams.readLine (#13857).

  • Added high-level asyncnet.sendTo and asyncnet.recvFrom UDP functionality.

  • dollars.$ now works for unsigned ints with nim js.

  • Improvements to the bitops module, including bitslices, non-mutating versions of the original masking functions, mask/masked, and varargs support for bitand, bitor, and bitxor.

  • sugar.=> and sugar.-> changes: Previously (x, y: int) was transformed into (x: auto, y: int), it now becomes (x: int, y: int) for consistency with regular proc definitions (although you cannot use semicolons).

    Pragmas and using a name are now allowed on the lefthand side of =>. Here is an example of these changes:

    import sugar
    foo(x, y: int) {.noSideEffect.} => x + y
    # is transformed into
    proc foo(x: int, y: int): auto {.noSideEffect.} = x + y
  • The fields of times.DateTime are now private, and are accessed with getters and deprecated setters.

  • The times module now handles the default value for DateTime more consistently. Most procs raise an assertion error when given an uninitialized DateTime, the exceptions are == and $ (which returns "Uninitialized DateTime"). The proc times.isInitialized has been added which can be used to check if a DateTime has been initialized.

  • Fix a bug where calling close on io streams in osproc.startProcess was a noop and led to hangs if a process had both reads from stdin and writes (e.g. to stdout).

  • The callback that is passed to system.onThreadDestruction must now be .raises: [].
  • The callback that is assigned to system.onUnhandledException must now be .gcsafe.

  • osproc.execCmdEx now takes an optional input for stdin, workingDir and env parameters.

  • Added a ssl_config module containing lists of secure ciphers as recommended by Mozilla OpSec

  • net.newContext now defaults to the list of ciphers targeting “Intermediate compatibility” per Mozilla’s recommendation instead of ALL. This change should protect users from the use of weak and insecure ciphers while still provides adequate compatibility with the majority of the Internet.

  • A new module std/jsonutils with hookable jsonTo,toJson,fromJson operations for json serialization/deserialization of custom types was added.

  • A new proc heapqueue.find[T](heap: HeapQueue[T], x: T): int to get index of element x was added.
  • Added rstgen.rstToLatex a convenience proc for renderRstToOut and initRstGenerator.
  • Added os.normalizeExe.
  • macros.newLit now preserves named vs unnamed tuples.
  • Added random.gauss, that uses the ratio of uniforms method of sampling from a Gaussian distribution.
  • Added typetraits.elementType to get the element type of an iterable.
  • typetraits.$ changes: $(int,) is now "(int,)" instead of "(int)"; $tuple[] is now "tuple[]" instead of "tuple"; $((int, float), int) is now "((int, float), int)" instead of "(tuple of (int, float), int)"
  • Added macros.extractDocCommentsAndRunnables helper.

  • strformat.fmt and strformat.& support specifier =. fmt"{expr=}" now expands to fmt"expr={expr}".
  • Deprecations: instead of os.existsDir use dirExists, instead of os.existsFile use fileExists.

  • Added the jsre module, Regular Expressions for the JavaScript target..
  • Made maxLines argument Positive in logging.newRollingFileLogger, because negative values will result in a new file being created for each logged line which doesn’t make sense.
  • Changed log in logging to use proper log level for JavaScript, e.g. debug uses console.debug, info uses, warn uses console.warn, etc.
  • Tables, HashSets, SharedTables and deques don’t require anymore that the passed initial size must be a power of two - this is done internally. Proc rightSize for Tables and HashSets is deprecated, as it is not needed anymore. takes val: int again not val: Positive; i.e. it can “count down” again.
  • Removed deprecated symbols from macros module, some of which were deprecated already in 0.15.
  • Removed sugar.distinctBase, deprecated since 0.19. Use typetraits.distinctBase.
  • asyncdispatch.PDispatcher.handles is exported so that an external low-level libraries can access it.

  • std/with, sugar.dup now support object field assignment expressions:
    import std/with
    type Foo = object
      x, y: int
    var foo = Foo()
    with foo:
      x = 10
      y = 20
    echo foo
  • Proc math.round is no longer deprecated. The advice to use strformat instead cannot be applied to every use case. The limitations and the (lack of) reliability of round are well documented.

  • Added getprotobyname to winlean. Added getProtoByname to nativesockets which returns a protocol code from the database that matches the protocol name.

  • Added missing attributes and methods to dom.Navigator like deviceMemory, onLine, vibrate(), etc.

  • Added strutils.indentation and strutils.dedent which enable indented string literals:
    import strutils
    echo dedent """
  • Added initUri(isIpv6: bool) to uri module, now uri supports parsing ipv6 hostname.

  • Added readLines(p: Process) to osproc.

  • Added the below toX procs for collections. The usage is similar to procs such as sets.toHashSet and tables.toTable. Previously, it was necessary to create the respective empty collection and add items manually.
    • critbits.toCritBitTree, which creates a CritBitTree from an openArray of items or an openArray of pairs.
    • deques.toDeque, which creates a Deque from an openArray.
    • heapqueue.toHeapQueue, which creates a HeapQueue from an openArray.
    • intsets.toIntSet, which creates an IntSet from an openArray.
  • Added progressInterval argument to asyncftpclient.newAsyncFtpClient to control the interval at which progress callbacks are called.

  • Added os.copyFileToDir.

Language changes

  • The =destroy hook no longer has to reset its target, as the compiler now automatically inserts wasMoved calls where needed.
  • The = hook is now called =copy for clarity. The old name = is still available so there is no need to update your code. This change was backported to 1.2 too so you can use the more readable =copy without loss of compatibility.

  • In the newruntime it is now allowed to assign to the discriminator field without restrictions as long as the case object doesn’t have a custom destructor. The discriminator value doesn’t have to be a constant either. If you have a custom destructor for a case object and you do want to freely assign discriminator fields, it is recommended to refactor the object into 2 objects like this:

      MyObj = object
        case kind: bool
        of true: y: ptr UncheckedArray[float]
        of false: z: seq[int]
    proc `=destroy`(x: MyObj) =
      if x.kind and x.y != nil:

    Refactor into:

      MySubObj = object
        val: ptr UncheckedArray[float]
      MyObj = object
        case kind: bool
        of true: y: MySubObj
        of false: z: seq[int]
    proc `=destroy`(x: MySubObj) =
      if x.val != nil:
  • getImpl on enum type symbols now returns field syms instead of idents. This helps with writing typed macros. The old behavior for backwards compatibility can be restored with --useVersion:1.0.
  • The typed AST for proc headers will now have the arguments be syms instead of idents. This helps with writing typed macros. The old behaviour for backwards compatibility can be restored with --useVersion:1.0.
  • let statements can now be used without a value if declared with importc/importcpp/importjs/importobjc.
  • The keyword from is now usable as an operator.
  • Exceptions inheriting from system.Defect are no longer tracked with the .raises: [] exception tracking mechanism. This is more consistent with the built-in operations. The following always used to compile (and still does):
    proc mydiv(a, b): int {.raises: [].} =
      a div b # can raise an DivByZeroDefect

    Now also this compiles:

    proc mydiv(a, b): int {.raises: [].} =
      if b == 0: raise newException(DivByZeroDefect, "division by zero")
      else: result = a div b

    The reason for this is that DivByZeroDefect inherits from Defect and with --panics:on Defects become unrecoverable errors.

  • Added the thiscall calling convention as specified by Microsoft, mostly for hooking purposes.
  • Deprecated the {.unroll.} pragma, because it was always ignored by the compiler anyway.
  • Removed the deprecated strutils.isNilOrWhitespace.
  • Removed the deprecated sharedtables.initSharedTable.
  • Removed the deprecated asyncdispatch.newAsyncNativeSocket.
  • Removed the deprecated dom.releaseEvents and dom.captureEvents.

  • Removed sharedlists.initSharedList, was deprecated and produces undefined behaviour.

  • There is a new experimental feature called “strictFuncs” which makes the definition of .noSideEffect stricter. See here for more information.

  • “for-loop macros” (see the manual) are no longer an experimental feature. In other words, you don’t have to write pragma {.experimental: "forLoopMacros".} if you want to use them.

  • Added the .noalias pragma. It is mapped to C’s restrict keyword for the increased performance this keyword can enable.

  • items no longer compiles with enums with holes as its behavior was error prone, see #14004.
  • system.deepcopy has to be enabled explicitly for --gc:arc and --gc:orc via --deepcopy:on.

  • Added the std/effecttraits module for introspection of the inferred effects. We hope this enables async macros that are precise about the possible exceptions that can be raised.
  • The pragma blocks {.gcsafe.}: ... and {.noSideEffect.}: ... can now also be written as {.cast(gcsafe).}: ... and {.cast(noSideEffect).}: .... This is the new preferred way of writing these, emphasizing their unsafe nature.

Compiler changes

  • Specific warnings can now be turned into errors via --warningAsError[X]:on|off.
  • The define and undef pragmas have been de-deprecated.
  • New command: nim r main.nim [args...] which compiles and runs main.nim, and implies --usenimcache so that the output is saved to $nimcache/main$exeExt, using the same logic as nim c -r to avoid recompilations when sources don’t change. Example:
    nim r compiler/nim.nim --help # only compiled the first time
    echo 'import os; echo getCurrentCompilerExe()' | nim r - # this works too
    nim r compiler/nim.nim --fullhelp # no recompilation
    nim r --nimcache:/tmp main # binary saved to /tmp/main
  • --hint:processing is now supported and means --hint:processing:on (likewise with other hints and warnings), which is consistent with all other bool flags. (since 1.3.3).
  • nim doc -r main and nim rst2html -r main now call openDefaultBrowser.
  • Added the new hint --hint:msgOrigin will show where a compiler msg (hint|warning|error) was generated; this helps in particular when it’s non obvious where it came from either because multiple locations generate the same message, or because the message involves runtime formatting.
  • Added the new flag --backend:js|c|cpp|objc (or -b:js etc), to change the backend; can be used with any command (e.g. nim r, doc, check etc); safe to re-assign.
  • Added the new flag --doccmd:cmd to pass additional flags for runnableExamples, e.g.: --doccmd:-d:foo --threads use --doccmd:skip to skip runnableExamples and rst test snippets.
  • Added the new flag --usenimcache to output binary files to nimcache.
  • runnableExamples "-b:cpp -r:off": code is now supported, allowing to override how an example is compiled and run, for example to change the backend.
  • nim doc now outputs under $projectPath/htmldocs when --outdir is unspecified (with or without --project); passing --project now automatically generates an index and enables search. See docgen for details.
  • Removed the --oldNewlines switch.
  • Removed the --laxStrings switch for mutating the internal zero terminator on strings.
  • Removed the --oldast switch.
  • Removed the --oldgensym switch.
  • $getType(untyped) is now “untyped” instead of “expr”, $getType(typed) is now “typed” instead of “stmt”.
  • Sink inference is now disabled per default and has to enabled explicitly via --sinkInference:on. Note: For the standard library sink inference remains enabled. This change is most relevant for the --gc:arc, --gc:orc memory management modes.

Tool changes

  • nimsuggest now returns both the forward declaration and the implementation location upon a def query. Previously the behavior was to return the forward declaration only.


  • Fixed “repr() not available for uint{,8,16,32,64} under –gc:arc” (#13872)
  • Fixed “Critical: 1 completed Future, multiple await: Only 1 await will be awakened (the last one)” (#13889)
  • Fixed “crash on openarray interator with argument in stmtListExpr” (#13739)
  • Fixed “Some compilers on Windows don’t work” (#13910)
  • Fixed “httpclient hangs if it recieves an HTTP 204 (No Content)” (#13894)
  • Fixed ““distinct uint64” type corruption on 32-bit, when using {.borrow.} operators” (#13902)
  • Fixed “Regression: impossible to use typed pragmas with proc types” (#13909)
  • Fixed “openssl wrapper corrupts stack on OpenSSL 1.1.1f + Android” (#13903)
  • Fixed “C compile error with –gc:arc on version 1.2.0 “unknown type name ‘TGenericSeq’” (#13863)
  • Fixed “var return type for proc doesn’t work at c++ backend” (#13848)
  • Fixed “TimeFormat() should raise an error but craches at compilation time” (#12864)
  • Fixed “gc:arc cannot fully support threadpool with FlowVar” (#13781)
  • Fixed “simple ‘var openarray[char]’ assignment crash when the openarray source is a local string and using gc:arc” (#14003)
  • Fixed “Cant use expressions with when in type sections.” (#14007)
  • Fixed “for a in MyEnum gives incorrect results with enum with holes” (#14001)
  • Fixed “Trivial crash” (#12741)
  • Fixed “Enum with holes cannot be used as Table index” (#12834)
  • Fixed “spawn proc that uses typedesc crashes the compiler” (#14014)
  • Fixed “Docs Search Results box styling is not Dark Mode Friendly” (#13972)
  • Fixed “–gc:arc -d:useSysAssert undeclared identifier cstderr with newSeq” (#14038)
  • Fixed “issues in the manual” (#12486)
  • Fixed “Annoying warning: inherit from a more precise exception type like ValueError, IOError or OSError [InheritFromException]” (#14052)
  • Fixed “relativePath(“foo”, “/”) and relativePath(“/”, “foo”) is wrong” (#13222)
  • Fixed “[regression] parseEnum does not work anymore for enums with holes” (#14030)
  • Fixed “Exception types in the stdlib should inherit from CatchableError or Defect, not Exception” (#10288)
  • Fixed “Make debugSend and debugRecv procs public in smtp.nim” (#12189)
  • Fixed “xmltree need add raw text, when add style element” (#14064)
  • Fixed “raises requirement does not propagate to derived methods” (#8481)
  • Fixed “tests/stdlib/tgetaddrinfo.nim fails on NetBSD” (#14091)
  • Fixed “tests/niminaction/Chapter8/sdl/sdl_test.nim fails on NetBSD” (#14088)
  • Fixed “Incorrect escape sequence for example in jsffi library documentation” (#14110)
  • Fixed “HCR: Can not link exported const, in external library” (#13915)
  • Fixed “Cannot import std/unidecode” (#14112)
  • Fixed “macOS: dsymutil should not be called on static libraries” (#14132)
  • Fixed “nim jsondoc -o:doc.json filename.nim fails when sequences without a type are used” (#14066)
  • Fixed “algorithm.sortedByIt template corrupts tuple input under –gc:arc” (#14079)
  • Fixed “Invalid C code with lvalue conversion” (#14160)
  • Fixed “strformat: doc example fails” (#14054)
  • Fixed “Nim doc fail to run for nim 1.2.0 (nim 1.0.4 is ok)” (#13986)
  • Fixed “Exception when converting csize to clong” (#13698)
  • Fixed “[Documentation] overloading using named arguments works but is not documented” (#11932)
  • Fixed “import os + use of existsDir/dirExists/existsFile/fileExists/findExe in config.nims causes “ambiguous call’ error” (#14142)
  • Fixed “import os + use of existsDir/dirExists/existsFile/fileExists/findExe in config.nims causes “ambiguous call’ error” (#14142)
  • Fixed “runnableExamples doc gen crashes compiler with except Exception as e syntax” (#14177)
  • Fixed “[ARC] Segfault with cyclic references (?)” (#14159)
  • Fixed “Semcheck regression when accessing a static parameter in proc” (#14136)
  • Fixed “iterator walkDir doesn’t work with -d:useWinAnsi” (#14201)
  • Fixed “cas is wrong for tcc” (#14151)
  • Fixed “proc execCmdEx doesn’t work with -d:useWinAnsi” (#14203)
  • Fixed “Use -d:nimEmulateOverflowChecks by default?” (#14209)
  • Fixed “Old sequences with destructor objects bug” (#14217)
  • Fixed “[ARC] ICE when changing the discriminant of a return value” (#14244)
  • Fixed “[ARC] ICE with static objects” (#14236)
  • Fixed “[ARC] “internal error: environment misses: a” in a finalizer” (#14243)
  • Fixed “[ARC] compile failure using repr with object containing ref seq[string]” (#14270)
  • Fixed “[ARC] implicit move on last use happening on non-last use” (#14269)
  • Fixed “[ARC] Compiler crash with a recursive non-ref object variant” (#14294)
  • Fixed “htmlparser.parseHtml behaves differently using –gc:arc or –gc:orc” (#13946)
  • Fixed “Invalid return value of openProcess is NULL rather than INVALID_HANDLE_VALUE(-1) in windows” (#14289)
  • Fixed “ARC codegen bug with inline iterators” (#14219)
  • Fixed “Building koch on OpenBSD fails unless the Nim directory is in $PATH” (#13758)
  • Fixed “[gc:arc] case object assignment SIGSEGV: destroy not called for primitive type “ (#14312)
  • Fixed “Crash when using thread and –gc:arc “ (#13881)
  • Fixed “Getting “Warning: Cannot prove that ‘result’ is initialized” for an importcpp’d proc with var T return type” (#14314)
  • Fixed “nim cpp -r --gc:arc segfaults on caught AssertionError” (#13071)
  • Fixed “tests/async/tasyncawait.nim is recently very flaky” (#14320)
  • Fixed “Documentation nonexistent quitprocs module” (#14331)
  • Fixed “SIGSEV encountered when creating threads in a loop w/ –gc:arc” (#13935)
  • Fixed “nim-gdb is missing from all released packages” (#13104)
  • Fixed “sysAssert error with gc:arc on 3 line program” (#13862)
  • Fixed “compiler error with inline async proc and pragma” (#13998)
  • Fixed “[ARC] Compiler crash when adding to a seq[ref Object]” (#14333)
  • Fixed “nimvm: sysFatal: unhandled exception: ‘sons’ is not accessible using discriminant ‘kind’ of type ‘TNode’ [FieldError]” (#14340)
  • Fixed “[Regression] karax events are not firing “ (#14350)
  • Fixed “odbcsql module has some wrong integer types” (#9771)
  • Fixed “db_sqlite needs sqlPrepared” (#13559)
  • Fixed “[Regression] createThread is not GC-safe” (#14370)
  • Fixed “Broken example on hot code reloading” (#14380)
  • Fixed “runnableExamples block with except on specified error fails with nim doc” (#12746)
  • Fixed “compiler as a library: findNimStdLibCompileTime fails to find system.nim” (#12293)
  • Fixed “5 bugs with importcpp exceptions” (#14369)
  • Fixed “Docs shouldn’t collapse pragmas inside runnableExamples/code blocks” (#14174)
  • Fixed “Bad codegen/emit for hashes.hiXorLo in some contexts.” (#14394)
  • Fixed “Boehm GC does not scan thread-local storage” (#14364)
  • Fixed “RVO not exception safe” (#14126)
  • Fixed “runnableExamples that are only compiled” (#10731)
  • Fixed “foldr raises IndexError when called on sequence” (#14404)
  • Fixed “moveFile does not overwrite destination file” (#14057)
  • Fixed “doc2 outputs in current work dir” (#6583)
  • Fixed “[docgen] proc doc comments silently omitted after 1st runnableExamples” (#9227)
  • Fixed “nim doc --project shows ‘@@/’ instead of ‘../’ for relative paths to submodules” (#14448)
  • Fixed “re, nre have wrong start semantics” (#14284)
  • Fixed “runnableExamples should preserve source code doc comments, strings, and (maybe) formatting” (#8871)
  • Fixed “nim doc .. fails when runnableExamples uses $ [devel] [regression]” (#14485)
  • Fixed “items is 20%~30% slower than iteration via an index” (#14421)
  • Fixed “ARC: unreliable setLen “ (#14495)
  • Fixed “lent is unsafe: after #14447 you can modify variables with “items” loop for sequences” (#14498)
  • Fixed “var op = fn() wrongly gives warning ObservableStores with object of RootObj type” (#14514)
  • Fixed “Compiler assertion” (#14562)
  • Fixed “Can’t get ord of a value of a Range type in the JS backend “ (#14570)
  • Fixed “js: can’t take addr of param (including implicitly via lent)” (#14576)
  • Fixed “{.noinit.} ignored in for loop -> bad codegen for non-movable types” (#14118)
  • Fixed “generic destructor gives: Error: unresolved generic parameter” (#14315)
  • Fixed “Memory leak with arc gc” (#14568)
  • Fixed “escape analysis broken with lent” (#14557)
  • Fixed “wrapWords seems to ignore linebreaks when wrapping, leaving breaks in the wrong place” (#14579)
  • Fixed “lent gives wrong results with -d:release” (#14578)
  • Fixed “Nested await expressions regression: await a(await expandValue()) doesnt compile” (#14279)
  • Fixed “windows CI docs fails with strange errors” (#14545)
  • Fixed “[CI] tests/async/tioselectors.nim flaky test for freebsd + OSX CI” (#13166)
  • Fixed “seq.setLen sometimes doesn’t zero memory” (#14655)
  • Fixed “nim dump is roughly 100x slower in 1.3 versus 1.2” (#14179)
  • Fixed “Regression: devel docgen cannot generate document for method” (#14691)
  • Fixed “recently flaky tests/async/t7758.nim” (#14685)
  • Fixed “Bind no longer working in generic procs.” (#11811)
  • Fixed “The pegs module doesn’t work with generics!” (#14718)
  • Fixed “Defer is not properly working for asynchronous procedures.” (#13899)
  • Fixed “Add an ARC test with threads in a loop” (#14690)
  • Fixed “[goto exceptions] {.noReturn.} pragma is not detected in a case expression” (#14458)
  • Fixed “[exceptions:goto] C compiler error with dynlib pragma calling a proc” (#14240)
  • Fixed “Cannot borrow var float64 in infix assignment” (#14440)
  • Fixed “lib/pure/memfiles.nim: compilation error with –taintMode:on” (#14760)
  • Fixed “newWideCString allocates a multiple of the memory needed” (#14750)
  • Fixed “Nim source archive install: ‘’ fails with error: cp: cannot stat ‘bin/nim-gdb’: No such file or directory” (#14748)
  • Fixed “nim cpp -r tests/exception/t9657 hangs” (#10343)
  • Fixed “Detect tool fails on FreeBSD” (#14715)
  • Fixed “compiler crash: findUnresolvedStatic “ (#14802)
  • Fixed “seq namespace (?) regression” (#4796)
  • Fixed “Possible out of bounds string access in std/colors parseColor and isColor” (#14839)
  • Fixed “compile error on latest devel with orc and ssl” (#14647)
  • Fixed “[minor] $ wrong for type tuple” (#13432)
  • Fixed “Documentation missing on devel asyncftpclient” (#14846)
  • Fixed “nimpretty is confused with a trailing comma in enum definition” (#14401)
  • Fixed “Output arguments get ignored when compiling with –app:staticlib” (#12745)
  • Fixed “[ARC] destructive move destroys the object too early” (#14396)
  • Fixed “highlite.getNextToken() crashes if the buffer string is “echo “"”” (#14830)
  • Fixed “Memory corruption with –gc:arc with a seq of objects with an empty body.” (#14472)
  • Fixed “Stropped identifiers don’t work as field names in tuple literals” (#14911)
  • Fixed “Please revert my commit” (#14930)
  • Fixed “[ARC] C compiler error with inline iterators and imports” (#14864)
  • Fixed “AsyncHttpClient segfaults with gc:orc, possibly memory corruption” (#14402)
  • Fixed “[ARC] Template with a block evaluating to a GC’d value results in a compiler crash” (#14899)
  • Fixed “[ARC] Weird issue with if expressions and templates” (#14900)
  • Fixed “xmlparser does not compile on devel” (#14805)
  • Fixed “returning lent T from a var T param gives codegen errors or SIGSEGV” (#14878)
  • Fixed “[ARC] Weird issue with if expressions and templates” (#14900)
  • Fixed “threads:on + gc:orc + unittest = C compiler errors” (#14865)
  • Fixed “mitems, mpairs doesn’t work at compile time anymore” (#12129)
  • Fixed “strange result from executing code in const expression” (#10465)
  • Fixed “Same warning printed 3 times” (#11009)
  • Fixed “type alias for generic typeclass doesn’t work” (#4668)
  • Fixed “exceptions:goto Bug devel codegen lvalue NIM_FALSE=NIM_FALSE” (#14925)
  • Fixed “the –useVersion:1.0 no longer works in devel” (#14912)
  • Fixed “template declaration of iterator doesn’t compile” (#4722)
  • Fixed “Compiler crash on type inheritance with static generic parameter and equality check” (#12571)
  • Fixed “Nim crashes while handling a cast in async circumstances.” (#13815)
  • Fixed “[ARC] Internal compiler error when calling an iterator from an inline proc “ (#14383)
  • Fixed ““Cannot instantiate” error when template uses generic type” (#5926)
  • Fixed “Different raises behaviour for newTerminal between Linux and Windows” (#12759)
  • Fixed “Expand on a type (that defines a proc type) in error message “ (#6608)
  • Fixed “unittest require quits program with an exit code of 0” (#14475)
  • Fixed “Range type: Generics vs concrete type, semcheck difference.” (#8426)
  • Fixed “[Macro] Type mismatch when parameter name is the same as a field” (#13253)
  • Fixed “Generic instantiation failure when converting a sequence of circular generic types to strings” (#10396)
  • Fixed “initOptParser ignores argument after value option with empty value.” (#13086)
  • Fixed “[ARC] proc with both explicit and implicit return results in a C compiler error” (#14985)
  • Fixed “Alias type forgets implicit generic params depending on order” (#14990)
  • Fixed “[ARC] sequtils.insert has different behaviour between ARC/refc” (#14994)
  • Fixed “The documentation for “hot code reloading” references a non-existent npm package” (#13621)
  • Fixed “existsDir deprecated but breaking dir undeclared” (#15006)
  • Fixed “uri.decodeUrl crashes on incorrectly formatted input” (#14082)
  • Fixed “testament incorrectly reports time for tests, leading to wrong conclusions” (#14822)
  • Fixed “Calling peekChar with Stream returned from osproc.outputStream generate runtime error” (#14906)
  • Fixed “localPassC pragma should come after other flags” (#14194)
  • Fixed ““Could not load” dynamic library at runtime because of hidden dependency” (#2408)
  • Fixed “–gc:arc generate invalid code for {.global.} («nimErr_» in NIM_UNLIKELY)” (#14480)
  • Fixed “Using ^ from stdlib/math along with converters gives a match for types that aren’t SomeNumber” (#15033)
  • Fixed “[ARC] Weird exception behaviour from doAssertRaises” (#15026)
  • Fixed “[ARC] Compiler crash declaring a finalizer proc directly in ‘new’” (#15044)
  • Fixed “[ARC] C compiler error when creating a var of a const seq” (#15036)
  • Fixed “code with named arguments in proc of winim/com can not been compiled” (#15056)
  • Fixed “javascript backend produces javascript code with syntax error in object syntax” (#14534)
  • Fixed “–gc:arc should be ignored in JS mode.” (#14684)
  • Fixed “arc: C compilation error with imported global code using a closure iterator” (#12990)
  • Fixed “[ARC] Crash when modifying a string with mitems iterator” (#15052)
  • Fixed “[ARC] SIGSEGV when calling a closure as a tuple field in a seq” (#15038)
  • Fixed “pass varargs[seq[T]] to iterator give empty seq “ (#12576)
  • Fixed “Compiler crashes when using string as object variant selector with else branch” (#14189)
  • Fixed “JS compiler error related to implicit return and return var type” (#11354)
  • Fixed “nkRecWhen causes internalAssert in semConstructFields” (#14698)
  • Fixed “Memory leaks with async (closure iterators?) under ORC” (#15076)
  • Fixed “strutil.insertSep() fails on negative numbers” (#11352)
  • Fixed “Constructing a uint64 range on a 32-bit machine leads to incorrect codegen” (#14616)
  • Fixed “heapqueue pushpop() proc doesn’t compile” (#14139)
  • Fixed “[ARC] SIGSEGV when trying to swap in a literal/const string” (#15112)
  • Fixed “Defer and –gc:arc” (#15071)
  • Fixed “internal error: compiler/semobjconstr.nim(324, 20) example” (#15111)
  • Fixed “[ARC] Sequence “disappears” with a table inside of a table with an object variant” (#15122)
  • Fixed “[ARC] SIGSEGV with tuple assignment caused by cursor inference” (#15130)
  • Fixed “Issue with –gc:arc at compile time” (#15129)
  • Fixed “Writing an empty string to an AsyncFile raises an IndexDefect” (#15148)
  • Fixed “Compiler is confused about call convention of function with nested closure” (#5688)
  • Fixed “Nil check on each field fails in generic function” (#15101)
  • Fixed “{.nimcall.} convention won’t avoid the creation of closures” (#8473)
  • Fixed “smtp.nim(161, 40) Error: type mismatch: got <typeof(nil)> but expected ‘SslContext = void’” (#15177)
  • Fixed “[strscans] scanf doesn’t match a single character with $+ if it’s the end of the string” (#15064)
  • Fixed “Crash and incorrect return values when using readPasswordFromStdin on Windows.” (#15207)
  • Fixed “Possible capture error with fieldPairs and genericParams” (#15221)
  • Fixed “The StmtList processing of template parameters can lead to unexpected errors” (#5691)
  • Fixed “[ARC] C compiler error when passing a var openArray to a sink openArray” (#15035)
  • Fixed “Inconsistent unsigned -> signed RangeDefect usage across integer sizes” (#15210)
  • Fixed “toHex results in RangeDefect exception when used with large uint64” (#15257)
  • Fixed “Arc sink arg crash” (#15238)
  • Fixed “SQL escape in db_mysql is not enough” (#15219)
  • Fixed “Mixing ‘return’ with expressions is allowed in 1.2” (#15280)
  • Fixed “os.getFileInfo() causes ICE with –gc:arc on Windows” (#15286)
  • Fixed “[ARC] Sequence “disappears” with a table inside of a table with an object variant” (#15122)
  • Fixed “Documentation regression jsre module missing” (#15183)
  • Fixed “CountTable.smallest/largest() on empty table either asserts or gives bogus answer” (#15021)
  • Fixed “[Regression] Parser regression” (#15305)
  • Fixed “[ARC] SIGSEGV with tuple unpacking caused by cursor inference” (#15147)
  • Fixed “LwIP/FreeRTOS compile error - missing SIGPIPE and more “ (#15302)
  • Fixed “Memory leaks with async (closure iterators?) under ORC” (#15076)
  • Fixed “Bug compiling with –gc:arg or –gc:orc” (#15325)
  • Fixed “memory corruption in tmarshall.nim” (#9754)
  • Fixed “typed macros break generic proc definitions” (#15326)
  • Fixed “nim doc2 ignores –docSeeSrcUrl parameter” (#6071)
  • Fixed “The decodeData Iterator from cgi module crash” (#15369)
  • Fixed “|| iterator generates invalid code when compiling with –debugger:native” (#9710)
  • Fixed “Wrong number of variables” (#15360)
  • Fixed “Coercions with distinct types should traverse pointer modifiers transparently.” (#7165)
  • Fixed “Error with distinct generic TableRef” (#6060)
  • Fixed “Support images in nim docgen” (#6430)
  • Fixed “Regression. Double sem check for procs.” (#15389)
  • Fixed “uri.nim url with literal ipv6 address is printed wrong, and cannot parsed again” (#15333)
  • Fixed “[ARC] Object variant gets corrupted with cursor inference” (#15361)
  • Fixed “nim doc .. compiler crash (regression 0.19.6 => 1.0)” (#14474)
  • Fixed “cannot borrow result; what it borrows from is potentially mutated” (#15403)
  • Fixed “memory corruption for seq.add(seq) with gc:arc and d:useMalloc “ (#14983)
  • Fixed “DocGen HTML output appears improperly when encountering text immediately after/before inline monospace; in some cases won’t compile” (#11537)
  • Fixed “Deepcopy in arc crashes” (#15405)
  • Fixed “pop pragma takes invalid input” (#15430)
  • Fixed “tests/stdlib/tgetprotobyname fails on NetBSD” (#15452)
  • Fixed “defer doesnt work with block, break and await” (#15243)
  • Fixed “tests/stdlib/tssl failing on NetBSD” (#15493)
  • Fixed “strictFuncs doesn’t seem to catch simple ref mutation” (#15508)
  • Fixed “Sizeof of case object is incorrect. Showstopper” (#15516)
  • Fixed “[ARC] Internal error when trying to use a parallel for loop” (#15512)
  • Fixed “[ARC] Type-bound assign op is not being generated” (#15510)
  • Fixed “[ARC] Crash when adding openArray proc argument to a local seq” (#15511)
  • Fixed “VM: const case object gets some fields zeroed out at runtime” (#13081)
  • Fixed “regression(1.2.6 => devel): VM: const case object field access gives: ‘sons’ is not accessible” (#15532)
  • Fixed “Csources: huge size increase (x2.3) in 0.20” (#12027)
  • Fixed “Out of date error message for GC options” (#15547)
  • Fixed “dbQuote additional escape regression” (#15560)