Quick fix due to ordering of includes, had to add #include
<mlir/Transforms/DialectConversion.h> to include/concretelang/Conversion/Utils/GenericOpTypeConversionPattern.h
Composing error messages for `llvm::Error` is either done by using
`llvm::createStringError()` with an appropriate format string and
arguments or by writing to a `std::string`-backed
`llvm::raw_string_ostream` and passing the result to
`llvm::make_error<llvm::StringError>()` verbatim.
The new class `StreamStringError` encapsulates the latter solution
into a class with an appropriate stream operator and implicit cast
operators to `llvm::Error` and `llvm::Expected`.
Example usage:
llvm::Error foo(int i, size_t s, ...) {
...
if(...) {
return StreamStringError()
<< "Some error message with an integer: "
<< i << " and a size_t: " << s;
}
...
}
