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Low, High and a constructor cannot see a qualified nested ALIAS, while the declaration of the same name compiles

PRE-EXISTING, NOT FALLOUT FROM THE ALIAS-SCOPING WORK. Say this first because a reader meeting "qualified nested type refused" next to c01eb17a8 and regression-test-core-test-record-nested-type-section will assume those caused it. stable_linux_amd64/default/pinned (symlink dated 2026-08-29, predating the entire AliasOwnerCi column) refuses it with the byte-identical error.

The finding

The DECLARATION path and the CONSTRUCTION path answer "what may follow TOuter." from two different tables, and the qualified construction walk consults only one.

type
  TThing = class v: Integer; constructor Create; end;
  TOuter = class type TP = TThing; end;   { alias, in a class body, to a class }
var o: TOuter.TP;          { compiles }
begin
  o := TOuter.TP.Create;   { pascal26: error: class method not found (TP) }

Same qualifier, same alias, same owner, one line apart.

Matrix — pxx HEAD vs fpc 3.2.2, four spellings

spelling pxx fpc
A nested class ctor through owner, TOuter.TInner.Create v=1 v=1
B alias-to-class ctor through owner, TOuter.TP.Create refused v=2
C same alias, ctor through the target, TThing.Create v=3 v=3
D unit-level alias to a class, TQ.Create v=4 v=4

Row D is the row that names the defect. The constructor path is not alias-blind — an unqualified alias to a class constructs fine, on HEAD and on the pin. It is specifically the qualified walk that cannot see an alias. So this is not "the ctor path has never heard of aliases"; it is that its qualified walk resolves each hop through FindNestedType alone, while the declaration path (ParseTypeKindInner) tries FindNestedType and the alias table.

Low and High are the same defect and are the cheaper repro

Found while re-verifying the alias-scoping fix on a rebased tree, by widening a probe rather than by reading code:

type TTest = class type TRange = 0..10; end;
WriteLn(Ord(Low(TTest.TRange)), ' ', Ord(High(TTest.TRange)));

  fpc 3.2.2 : 0 10
  pxx HEAD  : pascal26:4: error: class method not found (TRange)
  pxx PIN   : pascal26:4: error: class method not found (TRange)   <- pre-existing

Same error string as the constructor case — and that is NOT evidence they are one defect. Corrected here by frankB before any work started, and the correction is load-bearing for whoever fixes this.

class method not found comes from the class-method path, which is where anything unresolved lands. One diagnostic across three sites is exactly as consistent with three separate fall-throughs to a common handler as with one cause. All three of my readings were taken at the error-reporting layer, which is downstream of wherever each site actually gives up — so they corroborate each other only about the last thing that happened to them, not about why.

Establish where each one gives up before assuming a shared fix. They may share one; the observation above does not show it. Low/High may not even consult the alias table for a reason different from the constructor's FindNestedType gate.

Note what this does to the sibling count. Default() and SizeOf() DID have the strip and were repaired by regression-test-core-test-record-nested-type-section; Low, High and the constructor did not. So the family is five intrinsics, two of which knew about qualified nested types and three of which never did — and the three that never did agree with each other perfectly, which is exactly why reading them against each other finds nothing.

Where

compiler/pasparser_expr.inc:7830 — the TOuter.TInner.Create arm. Both its entry gate and its hop loop are FindNestedType(...) >= 0, which matches only a nested class or record; an alias returns -1, the arm is skipped, and the flat IsClassType(name) path below sees TOuter rather than TP.

Note for whoever takes it: adding QualTypeOwnerCi here would be a copy that cannot fire. The alias-visibility rule is not what is missing — the alias-table LOOKUP is. Resolving a hop needs to fall back to the alias table and then require the target to be a class before accepting Create.

How it was found

Predicted from a mechanism before it was looked for. frankB, auditing the qualifier-strip sites while reviewing the alias-scoping regression, argued that a rule spelled per call site fails by an ABSENT copy — invisible precisely because the copies that exist agree with each other — and named the un-audited fourth site. This is that site. It turned out not to be an absent copy of that rule, but the prediction found the hole.

The residual that makes it worth ranking above a curiosity: two tables answering one question is the shape that predicts a fifth site. Anywhere a qualified A.B run is walked, ask which table each hop is resolved through.

OWNER SET BY frankD ON frankB'S EXPLICIT REQUEST, 2026-09-06

frankB asked for it in a message, having agreed to take the row and then found it could not claim it: the ticket was filed after its last pull, and it cannot pull because an -i test-core run is reading its sources. Recording a claim a session stated is attribution, not dispatch — this seat set the field, frankB owns the row.

frankB has Low/High loaded from 557d06627 (the ordinal-identity work: TrySetTypeBound, TryConstHighLowValue, TryFoldHighLowType), which is the reason it is cheaper there than here.

RESOLVED 2026-09-06 — and the central question came back NO

They were not one defect. The ticket asked for where each site gives up to be established before a shared fix was assumed. It was, by experiment:

  1. EatQualifiedTypePrefix (new, pasparser_class.inc) landed first and was wired into TryConstHighLowValue / TryFoldHighLowType only. Measured immediately after: Low(TTest.TRange) answered 1, and TTest.TP.Make still answered class method not found (TP), byte for byte the same message as before.
  2. So the bounds half and the constructor half share the emitter and nothing else. ErrorRecover('class method not found') is where anything unresolved lands; a refusal names the position and never the reason.

The bounds sites never STRIPPED the qualifier at all. The two constructor sites stripped it correctly and then asked the wrong table. Different failures, one message. Had one patch fixed all three, that would not have been evidence they were one defect either — the asymmetry is not in the fix count.

The constructor half is TWO sites, not one, and the ticket named only one

pasparser_expr.inc:7855 (.Create) was in the ticket. pasparser_lval.inc's nested-scope walk — the named-constructor spelling, TTest.TP.Make — was not, and it is a separate while … FindNestedType(ci, fieldName) >= 0 loop in a different file. Both now call FindNestedClassLikeCi.

THE TABLE THE TICKET NAMED IS NOT THE TABLE THE ROW IS IN

The "Where" note said to fall back to the alias table. The first implementation did exactly that — AliasTk, AliasElemRec, REC_UCLASS_BASE — built cleanly, self-hosted, and resolved nothing, because type TP = TThing where TThing is a class never reaches RegisterGeneralAlias at all: ParseTypeSection's IsClassType arm routes it to RegisterUClassAlias, a THIRD table (UClsAlias*, three columns, no owner).

Every field name in the wrong version was real and every fact checked about it was true. What was never checked was which registrar the declaration actually reached. Reading RegisterGeneralAlias's two call sites is what created the confidence — a census of the function I had already decided on. The measurement that broke it was a dump of the whole alias table: fourteen rows, all builtins, no TP. Ask which registrar ran, not which columns look like they would hold the answer.

So the family is not two tables answering "what may follow TOuter." — it is three, and the ticket's residual ("two tables is the shape that predicts a fifth site") was right about the shape and short by a table.

Scoping, stated rather than assumed

FindNestedClassLikeCi's alias lookup is not owner-scoped, because the declaration path is not either: measured, var x: TOther.TP compiles today for a TP declared in TTest's body, since UClsAlias* has no owner column. The construction path now matches that exactly and is no looser. Scoping both is a separate change with a new column in it.

Landed

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