[#569] Add more info to EOF exception in C++ README.md

compiler/extensions/cpp/README.md

@@ -416,7 +416,7 @@ a `zserio::CppRuntimeException` during parsing of binary data:
 | `BitStreamReader.cpp` | constructor | "BitStreamReader: Buffer size exceeded limit '[MAX_BUFFER_SIZE]' bytes!" | Throws if provided buffer is bigger that 536870908 bytes (cca 511MB) on 32-bit OS or 2**64/8-4 bytes on 64-bit OS. |
 | `BitStreamReader.cpp` | constructor | "BitStreamReader: Wrong buffer bit size ('[BUFFER_SIZE]' < '[SPECIFIED_BYTE_SIZE]')!" | Throws if provided buffer is smaller than specified bit size. This could happen only in case of wrong arguments. |
 | `BitStreamReader.cpp` | `throwNumBitsIsNotValid()` | "BitStreamReader: ReadBits #[NUM_BITS] is not valid, reading from stream failed!" | Throws if `readBits()`, `readSignedBits()`, `readBits64()` or `readSignedBits64()` has been called with wrong (too big) `numBits` argument. This could happen only in case of data inconsistency, e.g. if dynamic bit field has length bigger than 32 or 64 bits respectively. |
-| `BitStreamReader.cpp` | `throwEof()` | "BitStreamReader: Reached eof(), reading from stream failed!" | Throws if end of underlying buffer has been reached (reading beyond stream). This could happen only in case of data inconsistency, e.g. if array length is defined bigger than is actually stored in the stream). |
+| `BitStreamReader.cpp` | `throwEof()` | "BitStreamReader: Reached eof(), reading from stream failed!" | Throws if the end of the underlying buffer has been reached (reading beyond stream). This can happen in two cases: either due to data inconsistency or if the buffer size is set to 0 and data reading is requested. Data inconsistency can occur, for example, if the defined array length is greater than the actual data stored in the stream. |
 | `BitStreamReader.cpp` | `readVarSize()` | "BitStreamReader: Read value '[VARSIZE_VALUE]' is out of range for varsize type!" | Throws if `varsize` value stored in stream is bigger than 2147483647. This could happen only in case of data inconsistency when `varsize` value stored in the stream is wrong. |
 | `OptionalHolder.h` | `throwNonPresentException()` | "Trying to access value of non-present optional field!" | Throws if optional value is not present during access. This could happen only in case of data inconsistency when optional field is not present in the stream and there is a reference to it in some expression. |
 | Generated Sources | Object read constructor | "Read: Wrong offset for field [COMPOUND_NAME].[FIELD_NAME]: [STREAM_BYTE_POSITION] != [OFFSET_VALUE]!" | Throws in case of wrong offset. This could happen only in case of data inconsistency when offset value stored in the stream is wrong. |