NachoSoto 786f40feb9 Fix crash on trailing-comma generic arguments ...

Root cause:
- A trailing comma inside a generic argument list can produce an empty generic argument, for example:
  `OrderedDictionary<String, (status: Result<Int, Error>, messages: [String]),>`
- During composition, `ParserResultsComposed.resolveType` force-unwrapped
  `typeName.name.split(separator: " ").first!` when generic requirements were present.
- If the generic parameter was empty, this force unwrap crashed with
  `Unexpectedly found nil while unwrapping an Optional value`.

What changed:
- Hardened `ParserResultsComposed.resolveType` to skip generic-requirement lookup
  when the lookup token is empty (no force unwrap).
- Filtered out empty/whitespace generic arguments in SwiftSyntax parsing
  (`GenericType+SwiftSyntax`).
- Filtered out empty/whitespace generic arguments in string-based type inference
  (`String+TypeInference`).
- Added a regression spec in `ComposerSpec` that covers a constrained generic type
  containing a trailing comma in a generic argument list and asserts only two valid
  generic parameters are produced.

Repro script:
```bash
cat > /tmp/Repro.swift <<'SWIFT'
struct Example<A: RandomAccessCollection, B: RandomAccessCollection>
  where A.Element == String,
  B.Element == String
{
  let asyncTaskData: OrderedDictionary<
    String,
    (status: Result<Int, Error>, messages: [String]),
  >
}
SWIFT

cat > /tmp/inspect.stencil <<'STENCIL'
{% for type in types.structs %}
{% for variable in type.variables %}
{% if variable.name == "asyncTaskData" and variable.typeName.generic %}
GENERIC_COUNT={{ variable.typeName.generic.typeParameters.count }}
{% for p in variable.typeName.generic.typeParameters %}
PARAM={{ p.typeName.name }}
{% endfor %}
{% endif %}
{% endfor %}
{% endfor %}
STENCIL

# Before this fix: crashes with Trace/BPT trap.
# After this fix:
#   GENERIC_COUNT=2
#   PARAM=String
#   PARAM=(status: Result<Int, Error>, messages: [String])
sourcery --disableCache --sources /tmp/Repro.swift --templates /tmp/inspect.stencil --output /tmp/out.txt
cat /tmp/out.txt
```

2026-02-09 12:34:09 -08:00

..

Sources

Fix crash on trailing-comma generic arguments

2026-02-09 12:34:09 -08:00

Supporting Files

Caching swift templates (#240)

2017-05-09 22:41:21 +02:00