[PATCH] D81915: [ObjectYAML][DWARF] Let writeVariableSizedInteger() return Error.

[James Henderson via Phabricator via llvm-commits]

jhenderson added inline comments.


================
Comment at: llvm/lib/ObjectYAML/DWARFEmitter.cpp:39
 
+static Error errorWithContext(Error Err, StringRef SecName, StringRef Field) {
+  assert(Err);
----------------
This isn't too far off what I had in mind, but is probably more than what you actually need.

Take a look at ELFDumper.cpp in llvm-readobj. You'll see several instances where the function `toString` is used to convert an error into a string and then this string is used as part of a new error message. For example, in `printRelocation` you have the following:

```
  Expected<std::pair<const typename ELFT::Sym *, std::string>> Target =
      this->dumper()->getRelocationTarget(SymTab, R);
  if (!Target)
    this->reportUniqueWarning(createError(
        "unable to print relocation " + Twine(RelIndex) + " in section " +
        Twine(SecIndex) + ": " + toString(Target.takeError())));
```
When the `Target` contains an error, the `toString` method is used, combined with other context information into a new error message. Consequently, you'd explicitly build up your message with the lower-level error message and higher level things. For example:

```
      if (Error Err = writeVariableSizedInteger(
              Descriptor.Address, Range.AddrSize, OS, DI.IsLittleEndian))
        return createStringError(errc::not_supported, "unable to write debug_aranges address: " + toString(std::move(Err)));
```


================
Comment at: llvm/lib/ObjectYAML/DWARFEmitter.cpp:65
   else
-    assert(false && "Invalid integer write size.");
+    return createStringError(errc::not_supported, "invalid integer write size");
+
----------------
I'd slightly modify this error to include the size that has been requested.


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D81915