## Bug
A bare `except:` followed by a `finally:` block raises a spurious
`ReraiseDefect: no exception to reraise` when compiled with `nim cpp`:
```nim
proc test() =
try:
raise newException(CatchableError, "x")
except:
discard
finally:
echo "finally"
test()
echo "after"
```
Expected output:
```
finally
after
```
Actual output:
```
finally
fatal.nim(53) sysFatal
Error: unhandled exception: no exception to reraise [ReraiseDefect]
```
This reproduces on every memory manager (`--mm:arc`, `--mm:orc`,
`--mm:refc`).
## Root cause
`genTryCpp` emits `try { ... } catch (Exception* T_) { ... }` followed
by a finally block that ends with `if (T_) std::rethrow_exception(T_);`.
In the *typed* except branches the codegen explicitly sets `T_ =
nullptr;` once the exception is handled, so the rethrow check in the
finally is a no-op.
The typeless `except:` branch (the `if t[i].len == 1` arm) emitted only
`popCurrentException()` and forgot to clear `T_`. After the handler body
finished, `T_` still pointed at the original exception, so the trailing
`if (T_) std::rethrow_exception(T_);` rethrew it. By that point Nim's
current-exception stack had already been popped, and the rethrow
surfaced as `ReraiseDefect`.
## Fix
Emit `T_ = nullptr;` at the start of the typeless `except:` handler
body, mirroring what is already done for the typed branches. This is the
same one-line treatment that fixed the analogous typed-except case for
#5871.
## Tests
Adds `tests/exception/treraise_typeless_except_finally.nim`, exercising
the bug pattern on `--mm:arc`, `--mm:orc`, and `--mm:refc`.
Locally:
- `tests/exception/` — 43 PASS, 0 FAIL, 3 SKIP
- new test passes on all three memory managers
## Backport
Tagged `[backport]` in the commit message — the same bug exists in
`version-2-2` and the fix applies cleanly there.
## Related
Independent of, but in the same family as, #25775 (also currently open).
Both are silent-finally / cpp-backend exception handling fixes; they
touch different lines of `genTryCpp` and don't conflict.
Co-authored-by: puffball1567 <17452514+puffball1567@users.noreply.github.com>
## Bug
When an `except T as e:` handler in the cpp backend raises a new
exception, the enclosing `finally` block is silently dropped under
`--mm:arc` and `--mm:orc`:
```nim
proc main() =
try:
try:
raise newException(CatchableError, "orig")
except CatchableError as e:
echo "inner: ", e.msg
raise newException(CatchableError, "re:" & e.msg)
finally:
echo "finally"
except CatchableError as outer:
echo "outer: ", outer.msg
main()
```
Expected output:
```
inner: orig
finally
outer: re:orig
```
Actual output on `nim cpp --mm:arc` (and `--mm:orc`):
```
inner: orig
outer: re:orig
```
The `finally` line is missing. The bug is specific to memory managers
that use destructor injection (arc/orc); under `--mm:refc` the original
code path works correctly because no destructor wrapper is injected.
## Root cause
When the body of `except T as e:` is processed under ARC/ORC, the
destructor injection pass injects a compiler-generated `nkHiddenTryStmt`
wrapper around the handler body to call `=destroy` on `e` when it goes
out of scope. That wrapper sits at the top of `p.nestedTryStmts` with
`inExcept = false`.
`finallyActions` (which inlines the user-finally body before a raise
propagates) only inspected the topmost entry of `nestedTryStmts`.
Because the wrapper has `inExcept = false`, the check short-circuited
and the user's finally was never inlined.
After the raise, C++'s rule that sibling catch clauses do not catch each
other's throws means the surrounding `catch(...)/finally` emitted by
`genTryCpp` never runs either, so the user's finally is silently
dropped.
## Fix
- Add an `isHidden` flag to `nestedTryStmts` entries, set to `t.kind ==
nkHiddenTryStmt` so compiler-injected try wrappers can be distinguished
from user-written ones.
- In `finallyActions`, walk past `isHidden` wrappers but stop at the
first user try. If that user try is in its except branch with a finally,
inline the finally body before the raise; otherwise leave the raise
untouched (the raise will be caught by that user try's own except
branches and the inner finally will run via normal unwinding, which is
what already happens correctly under refc).
Walking past wrappers fixes the `as e` case under arc/orc. Stopping at
user trys preserves the existing correct behaviour for nested
try/except/finally constructs (e.g. `tests/exception/tfinally.nim`'s
`nested_finally`), which would otherwise see the outer finally inlined
too eagerly when an inner raise is processed.
## Tests
Adds `tests/exception/tcpp_handler_raise_finally.nim` covering:
- `except T as e:` re-raise + outer finally
- typeless `except:` re-raise + outer finally
- try/finally without except (exception propagation through finally)
The test runs on `--mm:arc`, `--mm:orc`, and `--mm:refc`.
Locally verified on both `devel` and `version-2-2`:
- `tests/exception/` — 42 PASS, 0 FAIL, 3 SKIP
- `tests/destructor/` — all PASS
- `tests/cpp/` — all PASS (single unrelated failure: `tasync_cpp.nim`
needs the `jester` package)
- `megatest` — PASS for both `--mm:arc` and `--mm:refc`, including the
previously regressing `tfinally.nim`'s `nested_finally`
## Backport
Tagged `[backport]` in the commit message for inclusion in
`version-2-2`.
---------
Co-authored-by: puffball1567 <17452514+puffball1567@users.noreply.github.com>
Inline C++ comment emitted by `compiler/ccgstmts.nim:1168` into
generated code read `C++ exception occured, not under Nim's control`.
Doc-only change in the emitted source.
Signed-off-by: SAY-5 <SAY-5@users.noreply.github.com>
Co-authored-by: SAY-5 <SAY-5@users.noreply.github.com>
Returning or yielding from a closureiter must restore "external"
exception, but `popCurrentException` from `blockLeaveActions` was
getting in the way. So now `blockLeaveActions` doesn't emit
`popCurrentException` for returns in closureiters. I'm not a fan of this
"abstraction leakage", but don't see a better solution yet. Any input is
much appreciated.
---------
Co-authored-by: Andreas Rumpf <araq4k@proton.me>
TODO:
- [ ] test writing of .nif files
- [x] implement loading of fields in PType/PSym that might not have been
loaded
- [ ] implement interface logic
- [ ] implement pragma "replays"
- [ ] implement special logic for `converter`
- [ ] implement special logic for `method`
- [ ] test the logic holds up for `export`
- [ ] implement logic to free the memory of PSym/PType if memory
pressure is high
- [ ] implement logic to close memory mapped files if too many are open.
---------
Co-authored-by: demotomohiro <gpuppur@gmail.com>
Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>
Co-authored-by: Jacek Sieka <arnetheduck@gmail.com>
fixes#24770
e.g. `seq[(ObjectWithDestructors, string)]`/ For refc, a seq with
elements that have destructors will have `hasAsgn` flags. The flag is
the criteria whether a seq is thought as `containsGarbageCollectedRef`.
i.e. whether to `registerTraverseProc` for the type.
The culprit seems to be that `searchTypeForAux` doesn't consider the
element type of sequence, even it contains a string that should belong
to `GarbageCollectedRef`.
With this PR:
It now generates
```
nimRegisterThreadLocalMarker(TM__mSF73dT1lSI7DG58StKHLQ_5);
```
in refc
The lower half of cgen contains the main proc and HCR init code which
cause a large diff, so they are excluded from this PR. In general things
like generated defines, line directives, the stacktrace macros (`nimfr_`
etc) are also not done, since there are not exact equivalents for these
in NIFC (NIFC does generate line directives but based on the NIF line
info mechanism).
This adapts most of ccgstmts to cbuilder, missing C++ exceptions and
`genCaseGeneric`/`genIfForCaseUntil`. Rebased version of #24399 which
was split into some other PRs and since has had conflicts with #24416.
Not all uses of switch statements are implemented, `genCaseGeneric` and
`genIfForCaseUntil` still exist. The main purpose is to finish
`ccgreset` and `ccgtrav`.
Doing this early is useful so we can move the indentation logic into
`Builder` itself rather than mix it with the block logic in `ccgstmts`
(the `if` statements in #24381 have not been indented properly either).
However it also means `Builder` is now used for code that still
generates raw C code, so the diff won't be as clean when these get
updated.
`StructInitializer` is now used for most braced initializers in the C
generation, mostly in `genBracedInit`, `getNullValueAux`,
`getDefaultValue`. The exceptions are:
* the default case branch initializer for objects uses C99 designated
initializers with field names, which are not implemented for
`StructInitializer` yet (`siNamedStruct`)
* the uses in `ccgliterals` are untouched so all of ccgliterals can be
done separately and in 1 go
There is one case where `genBracedInit` does not use cbuilder, which is
the global literal variable for openarrays. The reason for this is
simply that variables with C array type are not implemented, which I
thought would be best to leave out of this PR.
For the simplicity of the implementation, code in `getNullValueAuxT`
that reset the initializer back to its initial state if the `Sup` field
did not have any fields itself, is now disabled. This was so the
compiler does not generate `{}` for the Sup field, i.e. `{{}}`, but
every call to `getNullValueAuxT` still generates `{}` if the struct
doesn't have any fields, so I don't know if it really breaks anything.
The case where the Sup field doesn't have any fields but the struct does
also would have generated `{{}, field}`.
Worst case, we can implement either the "resetting" or just disable the
generation of the `Sup` field if there are no fields total. But a better
fix might be to always generate `{0}` if the struct has no fields, in
line with the `char dummy` field that gets added for all objects with no
fields. This doesn't seem necessary for now but might be for the NIFC
output, in which case we can probably keep the logic contained inside
cbuilder (if no fields generated for `siOrderedStruct`/`siNamedStruct`,
we add a `0` for the `dummy` field). This would stipulate that all uses
of struct initializers are exhaustive for every field in structs.
(Inspired by this pragma in nir asm PR)
`inlineAsmSyntax` pragma allowing specify target inline assembler syntax
in `asm` stmt.
It prevents compiling code with different of the target CC inline asm
syntax, i.e. it will not allow gcc inline asm code to be compiled with
vcc.
```nim
proc nothing() =
asm {.inlineAsmSyntax: "gcc".} """
nop
"""
```
The current C(C++) backend implementation cannot generate code for gcc
and for vcc at the same time. For example, `{.inlineAsmSyntax: "vcc".}`
with the ICC compiler will not generate code with intel asm syntax, even
though ICC can use both gcc-like asm and vcc-like. For implement support
for gcc and for vcc at the same time in ICC compiler, we need to
refactor extccomp
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
Theoretical Benefits / Plans:
- Typed assembler-like language.
- Allows for a CPS transformation.
- Can replace the existing C backend by a new C backend.
- Can replace the VM.
- Can do more effective "not nil" checking and static array bounds
checking.
- Can be used instead of the DFA.
- Easily translatable to LLVM.
- Reasonably easy to produce native code from.
- Tiny memory consumption. No pointers, no cry.
**In very early stages of development.**
Todo:
- [x] Map Nim types to IR types.
- [ ] Map Nim AST to IR instructions:
- [x] Map bitsets to bitops.
- [ ] Implement string cases.
- [ ] Implement range and index checks.
- [x] Implement `default(T)` builtin.
- [x] Implement multi string concat.
- [ ] Write some analysis passes.
- [ ] Write a backend.
- [x] Integrate into the compilation pipeline.
* fixes#21995: align C with C++ backend behavior for empty raise statements
* make runtime behavior match across both C and C++ backend and all exception modes
* implements: [C++] constructor pragma improvement (fix#21921)
t
* fix test so it doesnt use echo in globals
* Update compiler/ccgtypes.nim
* Update lib/std/private/dragonbox.nim
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
