fixes#23898, supersedes #23966 and #23990
Since #20631 ambiguous type symbols in templates are rejected outright,
now we generate a symchoice for type nodes if they're ambiguous, a
generalization of what was done in #22375. This is done for generics as
well. Symchoices also handle type symbols better now, ensuring their
type is a `typedesc` type; this probably isn't necessary for everything
to work but it makes the logic more robust.
Similar to #23989, we have to prepare for the fact that ambiguous type
symbols behave differently than normal type symbols and either error
normally or relegate to other routine symbols if the symbol is being
called. Generating a symchoice emulates this behavior, `semExpr` will
find the type symbol first, but since the symchoice has other symbols,
it will count as an ambiguous type symbol.
I know it seems spammy to carry around an ambiguity flag everywhere, but
in the future when we have something like #23104 we could just always
generate a symchoice, and the symchoice itself would carry the info of
whether the first symbol was ambiguous. But this could harm compiler
performance/memory use, it might be better to generate it only when we
have to, which in the case of type symbols is only when they're
ambiguous.
fixes#23893
When type symbols are ambiguous, calls to them aren't allowed to be type
conversions and only routine symbols are considered instead. But the
compiler doesn't acknowledge that qualified symbols can be ambiguous,
`qualifiedLookUp` directly tries to access the identifier from the
module string table. Now it checks the relevant symbol iterators for any
symbol after the first received symbol, in which case the symbol is
considered ambiguous. `nkDotExpr` is also included in the whitelist of
node kinds for ambiguous type symbols (not entirely sure why this
exists, it's missing `nkAccQuoted` as well).
fixes#23749, refs #22716
`semIndirectOp` is used here because of the callback expressions, in
this case `db.getProc(...)`, and `semIndirectOp` calls `semOpAux` to
type its arguments before overloading starts. Hence it can opt in to
symchoices since overloading will resolve them.
fixes#23596
When importing a module and declaring an overloadable symbol with the
same name as the module in the same scope, the module symbol can take
over and make the declared overload impossible to access. Previously
enum overloading had a quirk that bypassed this in a context where a
specific enum type was expected but this was removed in #23588. Now this
is bypassed in every place where a specific type is expected since
module symbols don't have a type and so wouldn't be compatible anyway.
But the issue still exists in places where no type is expected like `let
x = modulename`. I don't see a way of fixing this without nerfing module
symbols to the point where they're not accessible by default, which
might break some macro code.
refs
https://github.com/nim-lang/Nim/issues/23586#issuecomment-2102113750
In #20091 a bad kind of type inference was mistakenly left in where if
an identifier `abc` had an expected type of an enum type `Enum`, and
`Enum` had a member called `abc`, the identifier would change to be that
enum member. This causes bugs where a local symbol can have the same
name as an enum member but have a different value. I had assumed this
behavior was removed since but it wasn't, and CI seems to pass having it
removed.
A separate PR needs to be made for the 2.0 branch because these lines
were moved around during a refactoring in #23123 which is not in 2.0.
fixes#23002, fixes#22841, refs comments in #23097
When an identifier is ambiguous in scope (i.e. multiple imports contain
symbols with the same name), attempt resolving it through type inference
(by creating a symchoice). To do this efficiently, `qualifiedLookUp` had
to be broken up so that `semExpr` can access the ambiguous candidates
directly (now obtained directly via `lookUpCandidates`).
This fixes the linked issues, but an example like:
```nim
let on = 123
{.warning[ProveInit]: on.}
```
will still fail, since `on` is unambiguously the local `let` symbol here
(this is also true for `proc on` but `proc` symbols generate symchoices
anyway).
Type symbols are not considered to not confuse the type inference. This
includes the change in sigmatch, up to this point symchoices with
nonoverloadable symbols could be created, they just wouldn't be
considered during disambiguation. Now every proper symbol except types
are considered in disambiguation, so the correct symbols must be picked
during the creation of the symchoice node. I remember there being a
violating case of this in the compiler, but this was very likely fixed
by excluding type symbols as CI seems to have found no issues.
The pure enum ambiguity test was disabled because ambiguous pure enums
now behave like overloadable enums with this behavior, so we get a
longer error message for `echo amb` like `type mismatch: got <MyEnum |
OtherEnum> but expected T`
refs #22605
Sym choice nodes are now only allowed to pass through semchecking if
contexts ask for them to (with `efAllowSymChoice`). Otherwise they are
resolved or treated as ambiguous. The contexts that can receive
symchoices in this PR are:
* Call operands and addresses and emulations of such, which will subject
them to overload resolution which will resolve them or fail.
* Type conversion operands only for routine symchoices for type
disambiguation syntax (like `(proc (x: int): int)(foo)`), which will
resolve them or fail.
* Proc parameter default values both at the declaration and during
generic instantiation, which undergo type narrowing and so will resolve
them or fail.
This means unless these contexts mess up sym choice nodes should never
leave the semchecking stage. This serves as a blueprint for future
improvements to intermediate symbol resolution.
Some tangential changes are also in this PR:
1. The `AmbiguousEnum` hint is removed, it was always disabled by
default and since #22606 it only started getting emitted after the
symchoice was soundly resolved.
2. Proc setter syntax (`a.b = c` becoming `` `b=`(a, c) ``) used to
fully type check the RHS before passing the transformed call node to
proc overloading. Now it just passes the original node directly so proc
overloading can deal with its typechecking.
fixes#22598, properly fixes#21887 and fixes test case issue number
When an enum field sym choice has to choose a type, check if its name is
ambiguous in the local scope, then check if the first symbol found in
the local scope is the first symbol in the sym choice. If so, choose
that symbol. Otherwise, give an ambiguous identifier error.
The dependence on the local scope implies this will always give
ambiguity errors for unpicked enum symchoices from generics and
templates and macros from other scopes. We can change `not
isAmbiguous(...) and foundSym == first` to `not (isAmbiguous(...) and
foundSym == first)` to make it so they never give ambiguity errors, and
always pick the first symbol in the symchoice. I can do this if this is
preferred, but no code from CI seems affected.
* clean up some test categories
* mention exact slice issue
* magics into system
* move trangechecks into overflow
* move tmemory to system
* try fix CI
* try fix CI
* final CI fix
