bug: method call on an inline `(expr as T)` is silently dropped

Type: bug (Track A — codegen) — silent no-op (method not invoked)
Status: done
Found: 2026-06-23, differential probe vs FPC
Closed: 2026-06-23
Severity: medium (a method call silently does nothing)

Resolution (2026-06-23)

Two parser gaps (front-end only, no codegen), both surfaced by (o as T).m:

ParseFactor's parenthesised-expression postfix . handled only fields and interface method calls; a non-interface class/record method (.m) fell to the AN_FIELD branch — a discarded field read, never a call. Added a mmi >= 0 branch that builds the class method call (static or virtual dispatch, Self = the grouped value), mirroring ParseClassRecordSelectors, and guarded mmi with FindUProp so a property still takes the field path. This fixed the expression form writeln((o as T).k(21)).
The statement form (o as T).m; never reached ParseFactor: a statement starting with ( hit ParseStatementAST's default branch, which skips tokens to ; — silently dropping it. Added a tkLParen: statement case that ParseExpr's the leading group (now resolving the call) and handles a trailing := (also fixes (p)^ := v statements, previously skipped too).

Verified (o as T).m; -> M, (o as T).k(21) -> 42 (virtual), (p)^ := 99, matching FPC. Controls (t := o as T; t.m, T(o).m) still work. Gate: make test (self-host byte-identical — front-end only) + FPC oracle. Closes bug-as-cast-inline-method-call.

Symptom

Calling a method directly on a parenthesized as-cast produces no call:

type ta = class end; tb = class(ta) procedure m; end;
procedure tb.m; begin writeln('M'); end;
var o: ta;
begin o := tb.create; (o as tb).m; end.
{ fpc: M    pxx: (prints nothing — m is never called) }

What works (controls)

Assign then call: t := o as tb; t.m; → M.
Hard cast inline: tb(o).m; → M.
The is/as operators themselves work elsewhere (if o is tb is correct).

So only the combination (<expr> as T).method mis-lowers — the as result is not used as the call's receiver, and the call is dropped silently.

Expected

(o as tb).m dispatches m on the cast reference (FPC: M).

Repro