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>
(cherry picked from commit 510ac84518)
fixes#24626
`createTypeboundOps` in sempass2 is called when generating destructors
for types including for explicit destructor calls, however it blocks
destructors from getting generated in a `nodestroy` proc. This causes
issues when a destructor is explicitly called in a `nodestroy` proc. To
fix this, allow destructors to get generated only for explicit
destructor calls in nodestroy procs.
(cherry picked from commit 793baf34ff)
fixes#22286
ref https://forum.nim-lang.org/t/10642
For backwards compatibilities, we might need to keep the changes under a
preview compiler flag. Let's see how many packags it break.
**TODO** in the following PRs
- [ ] Turn the `var T` destructors warning into an error with
`nimPreviewNonVarDestructor`
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
(cherry picked from commit 379299a5ac)
fixes#23690
```nim
dest.`:state` = src.`:state`
var :tmp_553651276 = dest.e1.a
`=wasMoved`(dest.e1.a)
dest.e1.a.kind = src.e1.a.kind
case dest.e1.a.kind
of 0:
dest.e1.a.a = src.e1.a.a
of 1:
`=copy`(dest.e1.a.c, src.e1.a.c)
case :tmp_553651276.kind
of 0:
of 1:
`=destroy`(:tmp_553651276.c)
```
`dest.e1.a.kind = src.e1.a.kind` changes the discrimant but it fails to
clear the memory of `dest.e1.a`. Before using hooks for copying, we need
to clear the dest, e.g. `=wasMoved(dest.e1.a.c)`.
```nim
dest.`:state` = src.`:state`
var :tmp_553651276 = dest.e1.a
`=wasMoved`(dest.e1.a)
dest.e1.a.kind = src.e1.a.kind
case dest.e1.a.kind
of 0:
`=wasMoved`(dest.e1.a.a)
dest.e1.a.a = src.e1.a.a
`=wasMoved`(dest.e1.a.b)
of 1:
`=wasMoved`(dest.e1.a.c)
`=copy`(dest.e1.a.c, src.e1.a.c)
case :tmp_553651276.kind
of 0:
of 1:
`=destroy`(:tmp_553651276.c)
```
(cherry picked from commit 262ff648aa)
fixes#22909
required by https://github.com/nim-lang/Nim/pull/23267
```nim
proc foo: string =
assert false
result = ""
```
In the function `foo`, `assert false` raises an exception, which can
cause `result` to be uninitialized if the default result initialization
is optimized out
(cherry picked from commit 7d9721007c)
fixes#23247closes#23251 (which accounts for why the openarray type is lifted
because ops are lifted for openarray conversions)
related: https://github.com/nim-lang/Nim/pull/18713
It seems to me that openarray doesn't own the data, so it cannot destroy
itself. The same case should be applied to
https://github.com/nim-lang/Nim/issues/19435. It shouldn't be destroyed
even openarray can have a destructor. A cleanup will be followed for
https://github.com/nim-lang/Nim/pull/19723 if it makes sense.
According to https://github.com/nim-lang/Nim/pull/12073, it lifts
destructor for openarray when openarray is sunk into the function, when
means `sink openarray` owns the data and needs to destroy it. In other
cases, destructor shouldn't be lifted for `openarray` in the first place
and it shouldn't destroy the data if it doesn't own it.
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
(cherry picked from commit 24a606902a)
`{.push overflowChecks: off.}` works in backends. Though it could be
implemented as a magic function.
By inspecting the generated C code, the overflow check is eliminated in
the debug or release mode.

Likewise, the index checking is probably not needed.
(cherry picked from commit d82bc0a29f)
* round out tuple unpacking assignment, support underscores
fixes#18710
* fix test messages
* use discard instead of continue
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
(cherry picked from commit 53d43e9671)
* adds documentation for `=wasMoved` and `=dup` hooks and small fixes
* Update doc/destructors.md
* Update doc/destructors.md
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
* tuple unpacking for vars as just sugar, allowing nesting
* set temp symbol AST
* hopeful fix some issues, add test for #19364
* always use temp for consts
* document, fix small issue
* fix manual indentation
* actually fix manual
* use helper proc
* don't resem temp tuple assignment
* fix#18977 disallow change branch of an object variant in ORC
* check errors for goto exception
* fixes conditions
* fixes tests
* add a test case for #18977
* fixes#21023; Segfault when mixing seqs, orc, variants and futures
* fixes none of the branches were explicitly selected
* add one more test
* one more test
* fixes#19795; remove parse pipeline
* isScript
* fixes nimscriptapi
* don't touch reorder
* check script
* fixes tests
* it seems implicit imports of system cause troubles
* access the first child of `nkStmtList`
* ignore comments
* minor messages
* perhaps increases hloLoopDetector
* the module is a stmtList, which changes the errors
* fixes nimdoc
* fixes tlinter
* fixes nim secret tests
* fixes arc_misc
* fixes nim secret tests again
* safe; fixes one more test
* GlobalError is the root cause too
* fixes parsing errors
* put emit types to the cfsForwardTypes section
* fixes#11852; `{.push checks:off}` now works in procs
* disable navigator
* fixes nimdoc
* add tests for JS
* fixes nimsuggest