Description

Fixes #2999.

SerializerUtils.compilePOJOSetter generates the bytecode that reads a column and calls the POJO's setter. On the
operand stack the value has the type of the reader method that produced it, which is frequently not the setter's
parameter type — and the conversion was only emitted for a few combinations (longToOpcode/floatToOpcode/
doubleToOpcode returned -1 for byte/short/char/boolean, and the Int8/UInt8/Int16/Enum8/Enum16/
Bool branches computed no conversion at all). The generated class therefore failed verification
(java.lang.VerifyError when the setter class is first linked, i.e. on the first row read) for e.g. an Int64,
UInt32, Float32, Float64 or BFloat16 column bound to a byte/short/char/boolean field, and for an
Int8/UInt8/Int16/Enum8/Enum16/Bool column bound to a long/float/double field.

Separately, the generic fallback branch emitted LDC of a class constant for the target type and CHECKCAST with its
internal name; for a primitive field that yields a class constant named "I"/"J" and a CHECKCAST int, and passes
the Object returned by readValue to a primitive descriptor. So Int128/UInt128/Int256/UInt256/Decimal*
columns could not be read into a primitive field at all, even though their value is a Number.

Changes

• SerializerUtils.binaryReaderMethodForType now records the reader's return type and delegates to a new
  emitPrimitiveConversion(mv, sourceType, targetType), which emits the full conversion for every pair following
  JLS narrowing/widening rules (a wide value is narrowed to int first, then to byte/short/char; boolean goes
  through the new numberToBoolean(double) because no opcode normalizes a number into 0/1). The now-unused
  longToOpcode/floatToOpcode/doubleToOpcode helpers are removed.
• The call site passes the setter's actual parameter type instead of ClickHouseDataType.toPrimitiveType(...), which
  maps char to short and so produced I2S rather than I2C for a char field.
• New else if (targetType.isPrimitive()) branch: the value is read with the wrapper class as the type hint and
  unboxed — convertToBoolean for a boolean field, otherwise objectToNumber (new helper) plus the matching
  Number.xxxValue() (intValue() + I2C for char, as Number has no charValue()). A column whose value is not
  a number now fails with a clear IllegalArgumentException instead of invalid bytecode.
• CHANGELOG.md and docs/features.md updated.

Not touched here (each is the subject of its own open PR on the same method, to keep the changes reviewable):
the UInt64 branch (#2997) and the Nullable marker for primitive fields (#2994).

Test

• SerializerUtilsTest.testCompiledSetterConvertsValueToPrimitiveFieldType — one @DataProvider covering every
  column type read into a primitive with all eight primitive field types, including narrowing (Int64 300 → byte
  44), unsigned readers (UInt32 0xFFFFFFFF → short -1), saturation (Float64 1e30 → Long.MAX_VALUE), the
  low-order-bits case (Int128 2^64+5 → long 5), boolean 0/non-zero, and the Number-valued column types
  (Int128, UInt128, Int256, Decimal64). Rows that already worked before this change (e.g. Int32 → byte,
  UInt16 → long, Bool → boolean) are included as contrast cases and assert their unchanged results.
• SerializerUtilsTest.testCompiledSetterRejectsPrimitiveFieldForNonNumericColumn — Date/IPv4/String/UUID
  into a numeric primitive field fails with IllegalArgumentException.
• SerializerUtilsTest.testCompiledSetterKeepsBoxedFieldValue — contrast case pinning that a boxed (Long) field
  still goes through readValue and is set as a Long.
• QueryTests.testQueryReadToPOJOWithPrimitiveFields (integration) — proves the fix on the live query path:
  queryAll(sql, Pojo.class, schema) with Int64→short, Float64→byte, Int128→long, Decimal64→double,
  Int64→boolean. This test fails with VerifyError on main and passes with the fix.

Verified: 47 of the new data rows fail on main (43 VerifyError, 4 in the non-numeric test) and all pass with the
fix; mvn -pl client-v2 test → 631 tests, 0 failures; the integration test above fails without the change.

Pre-PR validation gate

• Deterministic repro confirmed (unit + integration test failing on main)
• Root cause documented above
• Fix targets the root cause (the emitted conversion, at the point the setter descriptor is satisfied)
• Tests fail without the fix, pass with it
• No existing tests modified or weakened; full client-v2 unit suite green
• Convention compliance verified per AGENTS.md / docs/ai-review.md / docs/changes_checklist.md
• CHANGELOG.md entry added; docs/features.md updated

Compatibility

No public API change (objectToNumber and the numberToBoolean(double) overload are additions on
SerializerUtils, called from the generated bytecode). Every column/field combination that worked before produces
the same value; the affected combinations previously threw VerifyError, so no working behavior changes. The char
field conversion changes from I2S to I2C, which matches the setter's descriptor.