Don't capture with ast_pattern and do ast directly

packages/parser/lib/Lexer.re

@@ -44,24 +44,21 @@ let escape = [%sedlex.regexp? '\\'];
 
 let alpha = [%sedlex.regexp? 'a' .. 'z' | 'A' .. 'Z'];
 
-
 // https://drafts.csswg.org/css-syntax-3/#non-ascii-ident-code-point
 let non_ascii = [%sedlex.regexp?
-  0x00B7
-| 0x00C0 .. 0x00D6
-| 0x00D8 .. 0x00F6
-| 0x00F8 .. 0x037D
-| 0x037F .. 0x1FFF
-| 0x200C
-| 0x200D
-| 0x203F
-| 0x2040
-| 0x2070 .. 0x218F
-| 0x2C00 .. 0x2FEF
-| 0x3001 .. 0xD7FF
-| 0xF900 .. 0xFDCF
-| 0xFDF0 .. 0xFFFD
-| Compl (0x0000 .. 0x10000)]
+  0x00B7 | 0x00C0 .. 0x00D6 | 0x00D8 .. 0x00F6 | 0x00F8 .. 0x037D |
+  0x037F .. 0x1FFF |
+  0x200C |
+  0x200D |
+  0x203F |
+  0x2040 |
+  0x2070 .. 0x218F |
+  0x2C00 .. 0x2FEF |
+  0x3001 .. 0xD7FF |
+  0xF900 .. 0xFDCF |
+  0xFDF0 .. 0xFFFD |
+  Compl(0x0000 .. 0x10000)
+];
 
 let ident_start = [%sedlex.regexp? '_' | alpha | '$' | non_ascii | escape];
 
@@ -123,9 +120,7 @@ let at_rule_without_body = [%sedlex.regexp?
 let at_rule = [%sedlex.regexp? ("@", ident)];
 let at_keyframes = [%sedlex.regexp? ("@", "keyframes")];
 
-let identifier_start_code_point = [%sedlex.regexp?
-  alpha | non_ascii | '_'
-];
+let identifier_start_code_point = [%sedlex.regexp? alpha | non_ascii | '_'];
 let starts_with_a_valid_escape = [%sedlex.regexp? ('\\', Sub(any, '\n'))];
 
 let starts_an_identifier = [%sedlex.regexp?

packages/ppx/src/Css_to_runtime.re

@@ -38,11 +38,9 @@ let string_to_const = (~loc, s) => {
   };
 };
 let render_variable = (~loc, v) => {
-  open Ppxlib;
-  let txt = v |> String.concat(".") |> Longident.parse;
   Helper.Exp.ident({
     loc,
-    txt,
+    txt: v |> String.concat(".") |> Ppxlib.Longident.parse,
   });
 };
 

packages/ppx/src/Error.ml

@@ -0,0 +1,25 @@
+module Builder = Ppxlib.Ast_builder.Default
+
+let make ~description ~examples ~link =
+  let examples =
+    match examples with
+    | Some examples ->
+      Printf.sprintf "\n\nExample:\n  %s" (String.concat "\n  " examples)
+    | None -> ""
+  in
+  let link =
+    match link with
+    | Some link -> Printf.sprintf "\n\nMore info: %s" link
+    | None -> ""
+  in
+  Printf.sprintf "%s%s%s" description examples link
+
+let expr ~loc ?examples ?link description =
+  let message = make ~description ~examples ~link in
+  Builder.pexp_extension ~loc
+  @@ Ppxlib.Location.Error.to_extension
+  @@ Ppxlib.Location.Error.make ~loc message ~sub:[]
+
+let raise ~loc ?examples ?link description =
+  let message = make ~description ~examples ~link in
+  raise @@ Ppxlib.Location.raise_errorf ~loc "%s" message

packages/ppx/src/Error.mli

@@ -0,0 +1,17 @@
+val expr :
+  loc:Ppxlib.location ->
+  ?examples:string list ->
+  ?link:string ->
+  string ->
+  Ppxlib.expression
+
+(** This is a wrapper around `Ppxlib.Location.raise_errorf` that allows for
+    examples and a link to the documentation, similarly to
+    `Ppxlib.Location.raise_errorf` shouldn't be used much, prefer to use
+    `Error.expr` instead. *)
+val raise :
+  loc:Ppxlib.location ->
+  ?examples:string list ->
+  ?link:string ->
+  string ->
+  'raises

packages/ppx/src/generate.re

@@ -924,10 +924,10 @@ let rec getArgs = (expr, list) => {
   | Pexp_fun(arg, _, pattern, _) when !getIsLabelled(arg) =>
     Error.raise(
       ~loc=pattern.ppat_loc,
-      ~description="Dynamic components are defined with labeled arguments.",
-      ~example=Some("[%styled.div (~a, ~b) => {}]"),
+      ~examples=["[%styled.div (~a, ~b) => {}]"],
       ~link=
         "https://reasonml.org/docs/manual/latest/function#labeled-arguments",
+      "Dynamic components are defined with labeled arguments.",
     )
   | _ => (expr, list)
   };
@@ -951,20 +951,18 @@ let getLabeledArgs = (label, defaultValue, param, expr) => {
   if (getIsEmpty(param)) {
     Error.raise(
       ~loc=param.ppat_loc,
-      ~description=
-        "A dynamic component without props doesn't make much sense. This component should be static.",
-      ~example=None,
       ~link="https://styled-ppx.vercel.app/usage/dynamic-components",
+      "A dynamic component without props doesn't make much sense. This component should be static.",
     );
   };
 
   if (getNotLabelled(label)) {
     Error.raise(
       ~loc=param.ppat_loc,
-      ~description="Dynamic components are defined with labeled arguments.",
-      ~example=Some("[%styled.div (~a, ~b) => {}]"),
+      ~examples=["[%styled.div (~a, ~b) => {}]"],
       ~link=
         "https://reasonml.org/docs/manual/latest/function#labeled-arguments",
+      "Dynamic components are defined with labeled arguments.",
     );
   };