TObject.InstanceSize and TObject.ClassNameIs

Two of FPC's System-level root class operations, reachable with no uses, were missing:

pascal26: error: class method not found: InstanceSize
pascal26: error: "ClassNameIs": no such member on this record/class

Both now answer, on a class reference, an instance, a static TObject receiver and a TClass variable alike, byte-identical to fpc 3.2.2.

InstanceSize was pure omission

rtti_emit.inc's pass 2 has always written the instance size into the class blob:

{ instance size }
PatchDataU64(hdr + 16, UClsSize_[ci]);

The value was there; only the accessor was missing. __pxxInstanceSize is one field read, the same shape as __pxxClassParent two functions above it.

ClassNameIs

A case-insensitive compare of the class's own name, which does not walk the parent chain — TDer.Create.ClassNameIs('TBase') is False where InheritsFrom(TBase) is True. Reuses __pxxSameNameCI, already in the same unit, so the two cannot drift about what "same name" means.

Where they plug in

Three sites, all existing:

1. compiler/builtin/builtin.pas — the two helpers, beside __pxxClassName/__pxxClassParent, plus a named PXX_RTTI_INSTSIZE = 16 for the offset that was previously written by a bare literal on one side and never read on the other.
2. pasparser_call.inc — GenMakeClassRefOp gains two arms and IsClassRefOpName two names. ClassNameIs takes one argument, so it joins InheritsFrom's existing argument arm rather than getting a second copy of it.
3. pasparser_prog.inc — the token pre-scan that decides whether to pull the builtin unit. Missing this is the failure mode where the feature works in a program that happens to uses something and not in one that does not.

Verification

test/test_tobject_instancesize_and_classnameis.pas, wired into test-core, byte-identical to fpc 3.2.2 (cls 16 24 — the exact sizes agree, not just their ordering). The rows that carry the weight:

• poly — a static TObject variable holding a TDer reports 24, not TObject's size. This is what proves the blob is reached through the value at run time rather than resolved from the declared type at compile time. A compile-time answer would have passed every other row.
• ref — the same through a TClass variable, the other runtime path.
• nis3 — ClassNameIs('TBase') False and InheritsFrom(TBase) True on the same line, pinning that one walks the chain and the other does not.
• paren — FPC's empty-parens spelling on the no-argument form.

make compiler/pascal26 fixedpoint converged in 1 round; tools/gate.sh quick green.

Pin note: this touches compiler/builtin/**, which ships inside the binary, so the pinned compiler does not have the helpers until the next pin. Nothing in lib/** uses them, and the pinned compiler was re-checked against the modified builtin.pas (additive only — it compiles and runs a class program unchanged), so no pin is needed for this on its own.

Found by

A 33-program class/property/interface differential — properties (field-backed, getter/setter, read-only, indexed, default, inherited), virtual dispatch through a base reference, abstract/override, class methods and class vars, virtual class functions, is/as, ClassName/ClassParent/InheritsFrom, constructor and destructor chains, FreeAndNil, nil Free, interfaces with refcounting and Supports, method overloads, default parameters. 32 of 33 matched FPC exactly; this was the only gap.

Still missing from the root set

Inventoried while here, in rough order of how likely real code is to want them:

None of them is a one-liner the way InstanceSize was, and none has a caller yet. Filed here as an inventory rather than as eight tickets; promote individually when something asks.