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Comment by SupremumLimit | Hacker News Reader

I'd make this parse as "if (a) { if (b) { c; d; } }" and leave it at that. One of the reasons for significant indentation is to discourage this kind of code layout because it's hard to read.

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Okay, concretely, I'd like to see a translation of this real-world C++ code (taken from V8):

  #define RETURN_OBJECT_UNLESS_EXCEPTION(ISOLATE, RETURN_VALUE, RETURN_EMPTY) \
    if (!__allocation__.IsRetry()) {                                          \
      __object__ = __allocation__.ToObjectChecked();                          \
      if (__object__ == (ISOLATE)->heap()->exception()) { RETURN_EMPTY; }     \
      RETURN_VALUE;                                                           \
    }

This seems to be missing backslashes. I haven't considered how to deal with preprocessor macros, but the if statement converts very simply:

    if !__allocation__.IsRetry()
        __object__ = __allocation__.ToObjectChecked()
        if __object__ == (ISOLATE)->heap()->exception(); RETURN_EMPTY
        RETURN_VALUE

This isn't ambiguous like the example you suggested before.

That doesn't work, because if statement is inside preprocessor macro and must be in a single line.

I see what you mean. Yes, the if in a macro is a problem. I haven't addressed macros, that's a whole different can of worms.

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