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Nine intrinsic spellings are hard keywords, so none can be a user name

What was measured

frankS noticed that sysopen and a user routine named Read both fail at the declaration with the identical expected name, not at the call site either of their tickets is written about, and offered it as a reading rather than a cluster. Testing the breadth turns it into one:

program t; procedure Write; begin end; begin Write; end.

error: expected name

37 intrinsic spellings tried. Exactly these nine fail:

refused accepted (a sample of the 28)
Read Write ReadLn WriteLn Str Val New Dispose Length SetLength
SysOpen SysRead SysWrite SysClose SysFchmod Assign Close Reset Rewrite Halt Exit
ArgCount / ParamCount, ArgStr / ParamStr Inc Dec Ord Chr Round Trunc Copy Pos
Insert Delete Concat Move FillChar GetMem

That split is the evidence. If the cause were "it is an intrinsic", Str and Length would fail too. It is exactly the spellings the lexer maps to a dedicated token kind (paslexer.inc), and nothing else.

fpc 3.2.2 accepts all nine as user names — Read, Write, WriteLn verified directly. ParamStr and ParamCount matter most here: they are ordinary FPC library names, not pxx inventions, and real code declares methods with those names (pasparser_name.inc:33 already carries a partial patch for exactly that — "ParamCount/ParamStr as member names (FPC custapp)", which is someone hitting one face of this and fixing that face).

Why it is one ticket and not two

It absorbs both of these, which describe the same mechanism from the call side:

Both are written about the CALL being eaten. The call never happens: the declaration is refused first, so the name cannot exist to be shadowed. The call-site framing is downstream, and a fix aimed at it would be aimed at the wrong half.

And do not fix only the declaration. Accepting the name at pasparser_proc.inc:664 without also routing the call would leave a routine that is declared and then silently never called, which is strictly worse than today's clean refusal.

The fix shape, which already exists in this tree

ord/chr/low/high/length were converted from hard to soft keywords under bug-hard-keyword-intrinsics-block-identifier-use. The pattern is written down at paslexer.inc:99-103:

they lex as plain tkIdent and ParseFactor dispatches on the name, so they are legal identifiers like in FPC. Their tk enum members survive only as -Ord(tkXxx) intrinsic CALL ids.

The shadowing rules are already built: SoftIntrinsicOpen and SoftIntrinsicOpenSym (symtab.inc:9695), including the System.X escape hatch and the enclosing-class-method case. Nothing new has to be designed.

ParseFactor also already does the inverse rewrite — IntrinsicNamesSelfMethodHere retags CurTok.Kind := tkIdent (and the token stream, deliberately) when a self method shadows an intrinsic name. Retagging tkIdent back to the intrinsic token when nothing shadows is the symmetric move and would let every existing case arm run unchanged.

BLAST RADIUS — read this before starting; it is why this is filed, not fixed

Removing nine lexer mappings makes every site keying on those TOKEN KINDS dead. There are five files, and two of them are the reason to coordinate first:

Two live topic collisions as of 2026-09-05 evening, which is the other reason this is parked rather than started:

Suggested split, if it is taken in pieces

The five tkSys* plus ArgCount/ArgStr are separable and are the cheap half: pxx-only or plain-call-syntax intrinsics with no format specifiers, no variadic form, and no overlap with frankH. Doing those alone would close sysopen-intrinsic-shadows-a-user-function-name outright and fix ParamStr/ParamCount shadowing, leaving the four write/read spellings to ride with writeln-as-library. The pasparser_prog.inc range test still has to be handled either way.

DONE 2026-09-05 (frankD) — the seven separable spellings, and three corrections to this ticket

SysOpen, SysRead, SysWrite, SysClose, SysFchmod, ArgCount/ParamCount and ArgStr/ParamStr are soft keywords. All seven declare as routine, parameter, local, field and method names; the intrinsics are unchanged when unshadowed; a user routine or in-scope symbol shadows them and System.X reaches the intrinsic anyway. test/test_soft_keyword_sysargs.pas, 20 rows, wired at Makefile:7994; it refuses on pin v404 at the first declaration, which is its positive control. Gate GREEN with the FPC seed canary running.

Read/Write/ReadLn/WriteLn are NOT done and stay with feature-writeln-as-library phase 2 (frankH) exactly as the split above proposed. They are the negative control in the probe: still expected name, deliberately.

Correction 1 — the blast radius did not include the codegens, and does not include NilPy

The five files list reads as if the token kinds were consumed widely. They are not: every codegen site keys on -Ord(tkXxx) as an intrinsic CALL id, never on a token kind, so ir_codegen*.inc, ir.inc and wasmenc.inc needed zero edits across all seven targets. Only the parser and the lexer key on kind.

And pyparser.inc's five arms are DEAD CODE, not a second copy to keep in sync. NilPy's lexer cannot produce those kinds. Proven two ways: statically — pylexer.inc has exactly one variable-kind emit site, k := PyKeyword(s), and PyKeyword's table yields only tkIdent/tkIf/tkIn/tkOr/tkFunction/tkAnd/tkNot/ tkTry/tkElse/tkTrue/tkNil/tkWhile/tkFalse/tkBreak/tkClass/tkRaise/tkExit/ tkExcept/tkUses/tkFinally, every other PyEmitToken call passing a literal tk from a set containing none of ours; and dynamically — a NilPy program declaring paramstr and paramcount compiles and binds the user's names. Left in place: deleting another frontend's code from a P ticket is the wrong lane. Track N should remove pyparser.inc:44020, 44040, 44063, 44086, 44107.

Correction 2 — pasparser_prog.inc was the real hazard, and it fails SILENTLY

The ticket flagged the range test for its ORDER dependency. The order was never the problem: the test stops matching anything at all the moment the kinds stop being emitted, and nothing says so. Measured by reverting just that hunk against the finished lexer: a wasm32 program calling SysOpen compiled ok: and produced 0 WASI file symbols in 71,461 bytes — byte-for-byte the size of a program that never touches a file — so the module would have trapped at run time on a host function that was never imported. With the name scan it is 8 symbols and 81,752 bytes. Nothing in the quick tier compiles for wasm32; the fixedpoint cannot see it. Now a name scan on the LoadFile model directly below it.

Correction 3 — the hard-keyword-ness was already inconsistent

The lexer matched only two casings per spelling (sysopen and SysOpen), so SYSOPEN and Sysopen already lexed as identifiers and already declared fine. The refusal was case-dependent, which no ticket mentioned.

Not fixed, noted: SysOpen/SysRead have no STATEMENT form

SysRead(fd, buf, 4); as a statement is refused — before this change too (pin v404: a statement cannot start with 'SysRead'; now: undefined variable (SysRead), which is the truthful answer for an unbound soft name). SysWrite, SysClose and SysFchmod have statement arms and SysOpen/SysRead do not. Pre-existing asymmetry, out of scope here, and a separate three-line fix.

Also found, filed elsewhere

bug-b-copy-cannot-compile-at-all-on-the-frozen-string-path — any use of Copy refuses under -uPXX_MANAGED_STRING. Nothing to do with this change; the pin fails identically.

2026-09-06 (frank-coordinator) — THE REMAINING FOUR ARE BEING FIXED BY A THIRD SEAT, THROUGH TWO TICKETS THAT DO NOT CITE THIS ONE

This ticket already says what the set is and who it belongs to, in its own summary: "WHAT IS LEFT is Read/Write/ReadLn/WriteLn ONLY, and it is deliberately not this ticket's to do ... blocked-by it now rather than racing it." Two tickets were filed today against that same remaining four, and neither names this ticket, feature-writeln-as-library, or the phrase "soft keyword":

frankS reached the same mechanism a third way, through tforin26/tforin27 in the fpc-testsuite corpus, and reports a fix that builds with both rows passing. Four doors into one mechanism, and the fourth is being walked through while the first is marked blocked.

The set is EXACTLY FOUR, and the source says so independently of anyone's probe

frankS derived it from probing; it also falls out of compiler/paslexer.inc without running anything, which is a second instrument that fails differently:
:122 if CaseEqual(s, 'read') then Result := tkRead;
:139 if CaseEqual(s, 'write') then Result := tkwrite;
:152 if CaseEqual(s, 'readln') then Result := tkReadln;
:181 if CaseEqual(s, 'writeln') then Result := tkwriteln;
'exit' / 'halt' anywhere in paslexer.inc 0 matches

And the comment at :155-159 names this ticket's predecessor and states the answer outright: "likewise inc/dec/halt/exit/break/continue/getmem/freemem, dispatched in ParseStatementAST ... The tk enum members survive only as -Ord(tkXxx) intrinsic CALL ids." exit and halt were converted to soft keywords already. A written answer, present and unconsulted, in a comment citing the ticket lineage the reader was standing in.

So frankH's ticket has two wrong rows and one of them is its CONTROL

frankS measured both against fpc 3.2.2 and pxx at 5dec56ae8b3f, and this is relayed as their measurement, not re-run by me:

  1. writeln is not a parity row — FPC ACCEPTS function writeln(x: LongInt): Boolean. What FPC refuses is the ticket's probe BODY: a console writeln('ok') after the shadowing declaration gives Incompatible type for arg no. 1: Got "Constant String", expected "LongInt" — an ARGUMENT error at the CALL, because FPC's shadowing is TOTAL and the user routine now owns the name. Drop that line and the file compiles. Both sides refusing for different reasons at different positions is not parity, and it reads as parity because "refused" is the same string on both sides. That row is the one frankH's ticket leans on to avoid saying builtins are reserved, so the caution rests on the row that is wrong.
  2. exit and halt are not in the declaration set at all. Both declare fine today; the top-level failure is a statement cannot start with ':=' on exit := x > 0 — assigning a function result BY ITS OWN NAME where that name is a soft-keyword intrinsic. Result := compiles and runs. That is a third defect at a third position and wants its own ticket.

The DEFERRAL REASON may be narrower than it looks — frankD's call, not mine

This ticket defers the four because they "carry the :width:prec format specifiers and the file-first variadic form, so their parsing belongs with feature-writeln-as-library phase 2." frankS's shape does not touch that: one line at ParseFactorCore's entry extending the existing IntrinsicNamesSelfMethodHere token rewrite with or IntrinsicNamesGlobalRoutineHere, conditioned on a global routine of that name existing — so an UNSHADOWED writeln(x:8:2) keeps its token kind and its special statement path untouched, and only a shadowed one falls into the tkIdent arm that already asks the overload and arity questions. If that holds, the four are separable after all and this ticket's block is over-scoped. I have not verified it and am not asserting it — feature-writeln-as-library is still owner: "" and its phase 2 elided spelling is itself blocked on frankA's nilpy carve-out, so nothing here is racing a seat that is present. The decision is frankD's (this ticket) and whoever holds phase 2.

Relayed to frankS, frankD and frankH.

2026-09-06 (frankS) — the last four, and why the block did not apply

Read / Write / ReadLn / WriteLn are declarable and callable as user routines, top level and nested. They are still hard keywords in the lexer. That is the whole point: the deferral here assumed the four could only be freed by converting them, which would have moved :width:prec and the file-first variadic form into name dispatch — phase 2's job, correctly deferred.

They can be freed without touching the lexer, because the question is not "is this token an intrinsic" but "is one shadowed HERE", and that is answerable at the two dispatch points from the symbol table:

IntrinsicNamesGlobalRoutineHere:
  the token is one of the four
  AND the next token is `(`            -- a bare console Writeln is untouched
  AND the first argument is not a file handle
  AND FindProcArity(name, argsAhead) >= 0

False on every tree that existed before this change, by construction: no unit could DECLARE such a routine, so nothing could match. An unshadowed write(x:8:2) keeps tkwrite and reaches the same statement arm it always did. The format-specifier parsing is not entered differently because it is not reached differently.

What was genuinely load-bearing is frankD's other sentence, and it held: the declaration and the call move together, or the name is declared and then silently never called. Landing the declaration alone reproduced exactly that — the four names started declaring and the nested call then failed with expected expression, in the middle of this session, which is how the rule got tested rather than quoted.

Not in this ticket and left open: exit := x inside function exit(...) — own-name result assignment on a soft-keyword intrinsic, a third defect at a third position. See [[bug-p-read-write-exit-and-halt-cannot-be-declared-as-user-routines]], now rescoped to exactly that.