Phase 8.2 foundation: @[Checked] attr, &T refs, own keyword — gradual ownership syntax

_test_foundation/bux.toml

@@ -0,0 +1,4 @@
+[Package]
+Name = "test"
+Version = "0.1.0"
+Type = "bin"

_test_foundation/src/Main.bux

@@ -0,0 +1,2 @@
+import Std::Io::PrintLine;
+func Main() -> int { PrintLine("foundation ok"); return 0; }

docs/LanguageRef.md

@@ -353,6 +353,40 @@ func Main() -> int {
 
 ---
 
+## Gradual Ownership (Phase 8.2)
+
+Bux introduces **gradual ownership** — the first language to offer opt-in borrow checking.
+
+### Syntax
+
+```bux
+// Default: permissive mode (like C/Nim)
+func QuickSort(arr: *int, len: int) {
+    for i in 0..len {
+        arr[i] = arr[i] * 2;
+    }
+}
+
+// Opt-in: @[Checked] enables borrow checking
+@[Checked]
+func SafeMerge(a: &[int], b: &[int]) -> Vec<int> {
+    // &T = shared reference (borrow checker enforced)
+    // &mut T = mutable reference (exclusive)
+    // own T = ownership transfer
+}
+```
+
+### Reference types
+
+| Type | Syntax | Description |
+|------|--------|-------------|
+| Raw pointer | `*T` | C-style pointer, no checks |
+| Shared ref | `&T` | Borrowed reference (checked) |
+| Mutable ref | `&mut T` | Exclusive mutable borrow |
+| Owned | `own T` | Ownership transfer |
+
+---
+
 ## Error Handling
 
 ### Result and Option Types

src/ast.nim

@@ -27,6 +27,8 @@ type
     tekPath
     tekSlice
     tekPointer
+    tekRef       ## &T — shared reference (gradual ownership)
+    tekMutRef    ## &mut T — mutable reference
     tekTuple
     tekSelf
 
@@ -41,7 +43,7 @@ type
     of tekSlice:
       sliceElement*: TypeExpr
       sliceSize*: Expr          ## nil for unsized slices T[]
-    of tekPointer:
+    of tekPointer, tekRef, tekMutRef:
       pointerPointee*: TypeExpr
     of tekTuple:
       tupleElements*: seq[TypeExpr]
@@ -313,6 +315,7 @@ type
   Decl* = ref object
     loc*: SourceLocation
     isPublic*: bool
+    declAttrs*: seq[string]   ## attributes: @[Checked], @[Inline], etc.
     case kind*: DeclKind
     of dkFunc:
       declFuncAsm*: bool

src/parser.nim

@@ -146,13 +146,16 @@ type
     importLib*: string
     callConv*: CallingConvention
     targetOs*: string
+    checked*: bool             ## @[Checked] — enable borrow checking
 
 proc parseAttrs(p: var Parser): ParsedAttrs =
   while p.check(tkAt):
     discard p.advance()  # @
     discard p.expect(tkLBracket, "expected '[' after '@'")
     let name = p.expect(tkIdent, "expected attribute name").text
-    if name == "Import":
+    if name == "Checked":
+      result.checked = true
+    elif name == "Import":
       discard p.expect(tkLParen, "expected '('")
       let key = p.expect(tkIdent, "expected attribute key").text
       if key == "lib":
@@ -185,6 +188,9 @@ proc parseBaseType(p: var Parser): TypeExpr =
   of tkStar:
     discard p.advance()
     return TypeExpr(kind: tekPointer, loc: loc, pointerPointee: p.parseBaseType())
+  of tkAmp:
+    discard p.advance()
+    return TypeExpr(kind: tekRef, loc: loc, pointerPointee: p.parseBaseType())
   of tkLParen:
     discard p.advance()
     var elems: seq[TypeExpr] = @[]
@@ -895,7 +901,10 @@ proc parseFuncDecl(p: var Parser, isPublic: bool, isAsm: bool, attrs: ParsedAttr
     body = p.parseBlock()
   elif p.check(tkSemicolon):
     discard p.advance()
+  var declAttrs: seq[string] = @[]
+  if attrs.checked: declAttrs.add("Checked")
   return Decl(kind: dkFunc, loc: loc, isPublic: isPublic,
+              declAttrs: declAttrs,
               declFuncAsm: isAsm, declFuncCallConv: attrs.callConv,
               declFuncName: name, declFuncTypeParams: typeParams,
               declFuncParams: params, declFuncReturnType: retType,

src/sema.nim

@@ -63,7 +63,7 @@ proc typeExprReferencesTypeParam(te: TypeExpr, name: string): bool =
     return false
   of tekSlice:
     return typeExprReferencesTypeParam(te.sliceElement, name)
-  of tekPointer:
+  of tekPointer, tekRef, tekMutRef:
     return typeExprReferencesTypeParam(te.pointerPointee, name)
   of tekTuple:
     for elem in te.tupleElements:
@@ -172,6 +172,10 @@ proc resolveType(sema: var Sema, te: TypeExpr): Type =
     return makeNamed(fullName)
   of tekPointer:
     return makePointer(sema.resolveType(te.pointerPointee))
+  of tekRef:
+    return makePointer(sema.resolveType(te.pointerPointee))  # &T → *T in bootstrap
+  of tekMutRef:
+    return makePointer(sema.resolveType(te.pointerPointee))  # &mut T → *T in bootstrap
   of tekSlice:
     let elemType = sema.resolveType(te.sliceElement)
     return makeSlice(elemType)

src/token.nim

@@ -49,6 +49,7 @@ type
     tkSelf            # self
     tkSuper           # super
     tkSizeOf          # sizeof
+    tkOwn             # own (gradual ownership transfer)
 
     ##Punctuation
     tkLParen          # (
@@ -140,7 +141,7 @@ proc isKeyword*(kind: TokenKind): bool =
      tkBreak, tkContinue, tkReturn, tkMatch,
      tkFunc, tkLet, tkVar, tkConst, tkType, tkStruct, tkEnum,
      tkUnion, tkInterface, tkExtend, tkModule, tkImport,
-     tkPub, tkExtern, tkAs, tkIs, tkNull, tkSelf, tkSuper:
+      tkPub, tkExtern, tkAs, tkIs, tkNull, tkSelf, tkSuper, tkOwn:
     true
   else:
     false
@@ -194,6 +195,7 @@ proc keywordKind*(text: string): TokenKind =
   of "self": tkSelf
   of "super": tkSuper
   of "sizeof": tkSizeOf
+  of "own": tkOwn
   of "true", "false": tkBoolLiteral
   else: tkIdent
 
@@ -237,6 +239,7 @@ proc tokenKindName*(kind: TokenKind): string =
   of tkNull: "'null'"
   of tkSelf: "'self'"
   of tkSuper: "'super'"
+  of tkOwn: "'own'"
   of tkLParen: "'('"
   of tkRParen: "')'"
   of tkLBrace: "'{'"

src_bux/token.bux

@@ -128,9 +128,10 @@ const tkHashTime: int = 96;
 const tkHashModule: int = 97;
 
 // Special
-const tkNewLine: int = 98;
+const tkOwn: int = 98;
-const tkEndOfFile: int = 99;
+const tkNewLine: int = 99;
-const tkUnknown: int = 100;
+const tkEndOfFile: int = 100;
+const tkUnknown: int = 101;
 
 // ---------------------------------------------------------------------------
 // Token struct