While `a.push.apply(a, b)` is better for performance than the previous
`a = a.concat(b)` due to the fact that it doesn't create a new array,
there is a pretty big problem with it: depending on the JS engine, if
the second array is too long, it can [cause a
crash](https://tanaikech.github.io/2020/04/20/limitation-of-array.prototype.push.apply-under-v8-for-google-apps-script/)
due to the function `push` taking too many arguments. This has
unfortunately been what the codegen produces since 1.4.0 (commit
707367e1ca).
So string addition is now moved to a compilerproc that just uses a `for`
loop. From what I can tell this is the most compatible and the fastest.
Only potential problem compared to `concat` etc is with aliasing, i.e.
adding an array to itself, but I'm guessing it's enough that the length
from before the iteration is used, since it can only grow. The test
checks for aliased nim strings but I don't know if there's an extra
protection for them.
fixes#25008
It seems that `semOverloadedCall` evaluates the same node twice using
`tryConstExpr` in order for `efExplain` to print all the diagnostic
output. The problem is that `tryConstExpr` has side effects, i.e., it
changes the slot index of variables after VM execution.
There might be a way to do this but I couldn't find anything about it.
This is a very simple thing that goes a long way in certain situations.
Trying to avoid needing to switch to nimscript just to get:
```nim
# config.nims
import os
let srcDir = currentSourcePath.parentDir()
switch("define", &"ProjPath:\"{srcDir}\"")
```
with this change just needs:
```
# nim.cfg
d %= "ProjPath=$srcDir"
```
fixes#25123; fixes#11862
follow up https://github.com/nim-lang/Nim/pull/24442
ref https://github.com/nim-lang/Nim/pull/24441
> To fix this, fields from inactive branches are now detected in
semmacrosanity.annotateType (called in fixupTypeAfterEval) and marked to
prevent the codegen of their assignments. In
https://github.com/nim-lang/Nim/pull/24441 these fields were excluded
from the resulting node, but this causes issues when the node is
directly supposed to go back into the VM, for example as const values. I
don't know if this is the only case where this happens, so I wasn't sure
about how to keep that implementation working.
Object variants fields coming from inactive branches from VM are now
flagged `nfPreventCg`. We can ignore them, as done by the C backends.
fixes#25208
```nim
type Conf = object
val: int
const defaultConf = Conf(val: 123)
static:
var conf: Conf
conf = defaultConf
```
```nim
# opcLdConst is now always valid. We produce the necessary copy in the
# assignments now:
```
A `opcLdConst` is generated for `defaultConf` in `conf = defaultConf`.
According to the comment above, we need to handle the copy for
assignments of `opcLdConst`
fixes#25046
```nim
proc makeiter(v: string): iterator(): string =
return iterator(): string =
yield v
# loops
for c in makeiter("test")():
echo "loops ", c
```
becomes
```nim
var temp = makeiter("test")
for c in temp():
echo "loops ", c
```
for closures that might have side effects
fixes #25048
```nim
proc canFormAcycleAux =
of tyObject:
# Inheritance can introduce cyclic types, however this is not relevant
# as the type that is passed to 'new' is statically known!
# er but we use it also for the write barrier ...
if tfFinal notin t.flags:
# damn inheritance may introduce cycles:
result = true
```
It seems that all objects without `tfFinal` in their flags are
registering cycles. It doesn't seem that `Env` can be a cyclic type
because of inheritance since it is not going to be inherited after all
by another `Env` object type
