finalise legacy token compatibility policy (2.6.7)

.markdownlint.jsonc

@@ -0,0 +1,11 @@
+{
+  "MD004": { "style": "dash" },
+  "MD010": { "code_blocks": false },
+  "MD013": {
+    "line_length": 80,
+    "code_block_line_length": 120,
+    "tables": false,
+    "headings": false
+  },
+  "MD029": { "style": "ordered" }
+}

CHANGELOG.md

@@ -0,0 +1,10 @@
+# Changelog
+
+## Unreleased
+
+### Breaking changes
+
+- Reject legacy DDlog tokens that previously had inconsistent parser treatment:
+  `typedef`, `bigint`, `bit`, `double`, `float`, `signed`, bare `#`, and `<=>`.
+  Use `type`, sized integer types such as `u32`/`i64`, `f32`/`f64`, and
+  `#[...]` attributes instead.

docs/contents.md

@@ -5,6 +5,8 @@
 
 ## Core project documents
 
+- [Changelog](../CHANGELOG.md): User-facing release notes and migration
+  highlights.
 - [Repository layout](./repository-layout.md): Map of the repository tree,
   path responsibilities, and placement rules for contributors.
 - [Users' guide](./users-guide.md): User-visible syntax support and parser
@@ -82,6 +84,8 @@
   Plan for transformer declaration grammar alignment.
 - [2.6.6 resolve relation form coverage](./execplans/2-6-6-resolve-relation-form-coverage.md):
   Plan for relation form coverage and modelling alignment.
+- [2.6.7 finalize legacy token compatibility policy](./execplans/2-6-7-finalize-legacy-token-compatibility-policy.md):
+  Plan for closing the legacy-token compatibility policy.
 - [3.1.1 core rule and CST rule traits](./execplans/3-1-1-core-rule-and-cst-rule-traits.md):
   Plan for lint rule trait foundations.
 - [3.1.2 rule context struct](./execplans/3-1-2-rule-context-struct.md):

docs/ddlint-design.md

@@ -233,7 +233,10 @@ the syntax-layer contract before crate extraction: the parser now accepts only
 the canonical spec-form `index Name(field: Type, ...) on Atom`, rejects the
 older shorthand `index Name on Relation(columns)` with a targeted diagnostic,
 and exposes the typed field list plus normalized `on` target directly from the
-CST-backed `Index` wrapper.
+CST-backed `Index` wrapper. Legacy compatibility tokens follow the same
+parser-contract rule: `src/parser/reserved_tokens.rs` single-sources
+diagnostics for tokens that stay lexed for span precision but have no supported
+grammar semantics.
 
 Relation declarations use the same CST-backed boundary. The `Relation` wrapper
 models the declaration preamble with `RelationRole` (`Input`, `Output`, or

docs/developers-guide.md

@@ -113,6 +113,11 @@ parsing pipeline.
   (`D-REL-001` through `D-REL-003`) in `relations/preamble.rs`.
 - Keep typed consumer-facing relation metadata in `ast/relation.rs`, and
   inspection-only CST traversal in `ast/relation/inspect.rs`.
+- Route reserved-token diagnostics through `src/parser/reserved_tokens.rs`.
+  That module owns the parser-internal messages and the `rejection_for`
+  predicate for unsupported legacy tokens. The canonical public policy table
+  lives in `docs/differential-datalog-parser-syntax-spec-updated.md` section
+  `9.1`; avoid duplicating it in code comments or local scanner modules.
 
 ## Contributor workflow
 

docs/differential-datalog-parser-syntax-spec-updated.md

@@ -90,19 +90,26 @@ ______________________________________________________________________
 function calls at parse time. A bare `name(…)` parses as a variable application
 and is disambiguated later during name resolution.
 
+These case classes describe the intended naming categories. The current parser
+uses the generic `T_IDENT` token for identifiers and does not enforce the
+initial-case distinction in every context.
+
 ### 2.3 Reserved words and symbols
 
 The following **keywords** and **reserved operators** cannot be used as
 identifiers (final list should be kept 1:1 with the lexer):
 
 - **Keywords:** `type`, `function`, `extern`, `transformer`, `input`, `output`,
-  `relation`,`stream`,`multiset`,`index`,`on`,`primary`,`key`,`apply`,`match`,`if`,`else`,`for`,`in`,`then`,`skip`,`true`,`false`,`var`,`mut`,`return`,`break`,`continue`.
+  `relation`, `stream`, `multiset`, `index`, `on`, `primary`, `key`, `apply`,
+  `match`, `if`, `else`, `for`, `in`, `then`, `skip`, `true`, `false`, `var`,
+  `mut`, `return`, `break`, `continue`, and `as`.
 - **Special tokens:** `@`, `:-`, `,`, `;`, `:`, `::`, `.`, `&`, `'` (diff
   marker), `-<` (delay introducer), `=>` (implies), brackets and braces
-  `()[]{}`.
+  `()[]{}`, and `#` when it starts an attribute prefix `#[...]`.
 
-Reserved but not part of the grammar: `#`, `<=>`. Implementations must reject
-their use with a clear diagnostic.
+Reserved but not part of the grammar: `<=>` and bare `#` tokens not followed by
+`[` as an attribute prefix. Implementations must reject their use with a clear
+diagnostic.
 
 #### 2.3.1 Host‑language keyword reservation
 
@@ -184,7 +191,10 @@ intentional. -->
 
 **Note:** `++` (concatenation) and `^` (bit‑xor) are part of the operator table
 and are recognized as operators. `&` in row 13 is expression-only; head
-semantics are described in §7.3.
+semantics are described in §7.3. `:` is the implemented expression
+type-ascription operator, and `as` is the implemented expression cast operator;
+both use the type-operator binding level between shifts and bitwise operators.
+`as` is also the import alias keyword.
 
 ______________________________________________________________________
 
@@ -209,7 +219,7 @@ Attribute     ::= '#[' AttrBody ']'
 ### 5.2 Imports and types
 
 ```ebnf
-Import   ::= 'import' ScopedPath ';'
+Import   ::= 'import' ScopedPath ('as' LcName)? ';'
 Typedef  ::= 'type' UcName TypeParams? '=' Type ';'
 Type     ::= UcName TypeArgs? | TupleType | MapType | VecType | Primitive
 
@@ -220,6 +230,10 @@ Primitive ::= 'bool' | 'i8' | 'u8' | 'i16' | … | 'u128'
             | 'f32' | 'f64' | 'string' | 'interned'
 ```
 
+The import alias uses the documented `LcName` category. The current parser
+accepts the generic identifier token here and does not enforce that case
+restriction.
+
 ### 5.3 Functions and closures
 
 ```ebnf
@@ -553,19 +567,64 @@ ______________________________________________________________________
 ## 9.1 Legacy and compatibility tokens
 
 Implementations may encounter historical tokens from older DDlog parsers. This
-spec defines their treatment to aid migration:
+spec defines their treatment to aid migration. The lexer keeps the token kinds
+so diagnostics can point at the exact source span; unsupported uses are
+rejected by the parser.
 
 - `Aggregate(…)`: accepted and normalized during rule-body semantic
   extraction to the same canonical `(project, key)` aggregation contract used
   for `group_by(project, key)`; linters may emit a deprecation diagnostic.
 - `FlatMap`/`Inspect`: not language keywords; represent flatmap via RHS pattern
   binds instead. If used as keywords, reject with a targeted message.
-- `typedef`: not supported; use `type` definitions. Emit an error with a fix
-  hint.
-- Legacy type names such as `bigint`, `bit`, `double`, `float`, `signed`:
-  not in the grammar. Use sized integer types (`iN`/`uN`), and `f32`/`f64` for
-  floating‑point.
-- `as`: not a keyword in the updated grammar; reject its use as a keyword.
+- `typedef`: rejected.
+
+  ```plaintext
+  `typedef` is a legacy DDlog keyword; use `type` instead
+  ```
+
+- `as`: accepted as the import alias keyword and the implemented expression
+  cast operator; `:` is the implemented expression type-ascription operator.
+- `bigint`: rejected.
+
+  ```plaintext
+  `bigint` is a legacy type name; use a sized integer such as `i64` or `u64`
+  ```
+
+- `bit`: rejected.
+
+  ```plaintext
+  `bit` is a legacy type name; use an unsigned sized integer such as `u32`
+  ```
+
+- `double`: rejected.
+
+  ```plaintext
+  `double` is a legacy type name; use `f64`
+  ```
+
+- `float`: rejected.
+
+  ```plaintext
+  `float` is a legacy type name; use `f32`
+  ```
+
+- `signed`: rejected.
+
+  ```plaintext
+  `signed` is a legacy type name; use a signed sized integer such as `i32`
+  ```
+
+- `#`: accepted only as `#[...]`; bare uses are rejected.
+
+  ```plaintext
+  `#` is reserved; only `#[...]` attribute syntax is accepted
+  ```
+
+- `<=>`: rejected.
+
+  ```plaintext
+  `<=>` was reserved upstream but has no semantics in DDlog; remove it
+  ```
 
 Rationale and resolution status for the aggregation boundary: