libexpr: Deprecate or in non-keyword positions

Test cases courtesy of rhenrdic

Co-authored-by: Commentator2.0 <lix@crystal-cavern.systems>
Change-Id: Id8df684ddd00d07b49e1c9e68bf41ee6c0e6887c

lix/libexpr/parser/state.hh

@@ -42,6 +42,8 @@ struct State
     void nulFound(const PosIdx pos);
     void recSetMergeFound(const AttrPath & attrPath, const PosIdx pos);
     void recSetDynamicAttrFound(const PosIdx pos);
+    void orIdentifierFound(const PosIdx pos);
+    void orArgumentFound(const PosIdx pos);
     void addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_ptr<Expr> e, const PosIdx pos);
     void mergeAttrs(AttrPath & attrPath, ExprSet * source, ExprSet * target);
     void validateLambdaAttrs(AttrsPattern & pattern, PosIdx pos = noPos);
@@ -198,6 +200,34 @@ inline void State::recSetDynamicAttrFound(const PosIdx pos)
     });
 }
 
+// Added 2026-01-30
+inline void State::orIdentifierFound(const PosIdx pos)
+{
+    logWarning({
+        .msg = HintFmt(
+            "using %s as an identifier is deprecated because it cannot be used in most places (try "
+            "%s). Use %s to disable this warning.",
+            "or",
+            "let or = 1; in or",
+            "--extra-deprecated-features or-as-identifier"
+        ),
+        .pos = positions[pos],
+    });
+}
+// Added 2026-01-30
+inline void State::orArgumentFound(const PosIdx pos)
+{
+    logWarning({
+        .msg = HintFmt(
+            "using %s as an argument is deprecated because it is parsed with the wrong precedence "
+            "which may cause unexpected behavior. Use %s to disable this warning.",
+            "or",
+            "--extra-deprecated-features or-as-identifier"
+        ),
+        .pos = positions[pos],
+    });
+}
+
 inline void State::addAttr(ExprAttrs * attrs, AttrPath && attrPath, std::unique_ptr<Expr> e, const PosIdx pos)
 {
     AttrPath::iterator i;