fixes#25007
```nim
proc setLengthSeqUninit(s: PGenericSeq, typ: PNimType, newLen: int, isTrivial: bool): PGenericSeq {.
compilerRtl.} =
```
In this added function, only the line `zeroMem(dataPointer(result,
elemAlign, elemSize, newLen), (result.len-%newLen) *% elemSize)` is
removed from `proc setLengthSeqV2` when enlarging a sequence.
JS and VM versions simply use `setLen`.
Reworked closureiter transformation.
- Convolutedly nested finallies should cause no problems now.
- CurrentException state now follows nim runtime rules (pushes and pops
appropriately), and mimics normal code, which is somewhat buggy, see
#25031
- Previously state optimization (removing empty states or extra jumps)
missed some opportunities, I've reimplemented it to do everything
possible to optimize the states. At this point any extra states or jumps
should be considered a bug.
The resulting codegen (compiled binaries) is also slightly smaller.
**BUT:**
- I had to change C++ reraising logic, see expt.nim. Because with
closure iters `currentException` is not always in sync with C++'s notion
of current exception. From my tests and understanding of C++ runtime
there should not be any problems, but I'm only 99% sure :)
- I've reused `nfNoRewrite` flag in one specific case during the
transformation. This flag is also used in term-rewriting logic. Again,
99% sure, these 2 scenarios will never intersect.
Docs are routinely compiled on a different OS so often don't reflect
reality of CT-conditionals.
I bet there's a few of other places like this in the stdlib.
implements https://github.com/nim-lang/RFCs/issues/557
It inserts defect handing into a bare except branch
```nim
try:
raiseAssert "test"
except:
echo "nope"
```
=>
```nim
try:
raiseAssert "test"
except:
# New behaviov, now well-defined: **never** catches the assert, regardless of panic mode
raiseDefect()
echo "nope"
```
In this way, `except` still catches foreign exceptions, but panics on
`Defect`. Probably when Nim has `except {.foreign.}`, we can extend
`raiseDefect` to foreign exceptions as well. That's supposed to be a
small use case anyway.
`--legacy:noPanicOnExcept` is provided for a transition period.
Follow up https://github.com/nim-lang/Nim/pull/19512
ref https://github.com/nim-lang/Nim/issues/24794
Otherwise, `/Users/blue/Desktop/Nim/lib/system/mm/malloc.nim(4, 1)
Error: redefinition of 'allocImpl'; previous declaration here:
/Users/blue/Desktop/Nim/lib/system/memalloc.nim(51, 8)`
In `proc allocImpl*(size: Natural): pointer {.noconv, rtl, tags: [],
benign, raises: [].}`, `rtl` means it is an `importc` function instead
of a proc forward decl.
fixes#24664
```nim
proc main() =
for i in 0..1:
var s = "12345"
s.add s
echo s
main()
```
In the given example, `add` contains two steps: `prepareAdd` and
`appendString`. In the first step, a new buffer is created in order to
store the final doubled string. But it doesn't copy the null terminator,
neither zeromem the left unused spaces. It causes a problem because
`appendString` will copy itself which doesn't end with `\0` properly so
contaminated memory is copied instead.
```
var s = 12345\0
prepareAdd:
var s = 12345xxxxx\0
appendString:
var s = 1234512345x
```
ref https://github.com/nim-lang/Nim/pull/24686
With this PR
```nim
import std/streams
proc foo() =
var name = newStringStream("2r2")
raise newException(ValueError, "sh")
try:
foo()
except:
discard
echo 123
```
this example no longer leaks
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
closes https://github.com/nim-lang/RFCs/issues/554
Adds a symmetric difference operation to the language bitset type. This
maps to a simple `xor` operation on the backend and thus is likely
faster than the current alternatives, namely `(a - b) + (b - a)` or `a +
b - a * b`. The compiler VM implementation of bitsets already
implemented this via `symdiffSets` but it was never used.
The standalone binary operation is added to `setutils`, named
`symmetricDifference` in line with [hash
sets](https://nim-lang.org/docs/sets.html#symmetricDifference%2CHashSet%5BA%5D%2CHashSet%5BA%5D).
An operator version `-+-` and an in-place version like `toggle` as
described in the RFC are also added, implemented as trivial sugar.
updated version of #22193
After #22029 and the followups #23983 and #24005 which fixed issues with
it, `tyFromExpr` no longer match any proc params in generic type bodies
but delay all non-matching calls until the type is instantiated.
Previously the mechanism `fauxMatch` was used to pretend that any
failing match against `tyFromExpr` actually matched, but prevented the
instantiation of the type until later.
Since this mechanism is not needed anymore for `tyFromExpr`, it is now
only used for `tyError` to prevent cascading errors and changed to a
bool field for simplicity. A change in `semtypes` was also needed to
prevent calling `fitNode` on default param values resolving to type
`tyFromExpr` in generic procs for params with non-generic types, as this
would try to coerce the expression into a concrete type when it can't be
instantiated yet.
The aliases `tyProxy` and `tyUnknown` for `tyError` and `tyFromExpr` are
also removed for uniformity.
Lets single threaded applications benefit from tracking foreign cells as
well.
After this, `SmallChunk` technically doesn't need to act as a linked
list anymore I think, gotta investigate that more though.
The likelihood of overflowing `chunk.free` also rises, so to work around
that it might make sense to check `foreignCells` instead of adjusting
free space or replace free with a counter for the local capacity.
For Nim compile I can observe a ~10mb reduction, and smaller ones for
other projects.
Ref: https://github.com/nim-lang/Nim/issues/23788
There was a small leak in the above issue even after fixing the
segfault. The sizes of `free` and `acc` were changed to 32bit because
adding the `foreignCells` field will drastically increase the memory
usage for programs that hold onto memory for a long time if they stay as
64bit.
fixes#23742
Before my PR, `setLen(0)` doesn't free buffer if `s != nil`, but it
allocated unnecessary memory for `strs`. This PR rectifies this
behavior. `setLen(0)` no longer allocates memory for uninitialized
strs/seqs
`reset`, `wasMoved` and `move` doesn't support primitive types, which
generate `null` for these types. It is now produce `x = default(...)` in
the backend. Ideally it should be done by ast2ir in the future
fixes#4695
ref https://github.com/nim-lang/Nim/pull/15818
Since `nkState` is only for the main loop state labels and `nkGotoState`
is used only for dispatching the `:state` (since
https://github.com/nim-lang/Nim/pull/7770), it's feasible to rewrite the
loop body into a single case-based dispatcher, which enables support for
JS, VM backend. `nkState` Node is replaced by a label and Node pair and
`nkGotoState` is only used for intermediary processing. Backends only
need to implement `nkBreakState` and `closureIterSetupExc` to support
closure iterators.
pending https://github.com/nim-lang/Nim/pull/23484
<del> I also observed some performance boost for C backend in the
release mode (not in the danger mode though, I suppose the old
implementation is optimized into computed goto in the danger mode)
</del>
allPathsAsgnResult???
