Implement Display trait for Target in pmp-macro-misc to enhance flag formatting and readability

Cargo.toml

@@ -15,7 +15,8 @@ authors = ["Dean J. Karstedt <dk@cl.team>"]
 license-file = "LICENSE"
 
 [dependencies]
-pmp-emitter = { version = "1.0.0", path = "crates/pmp-emitter" }
+pmp-macro   = { path = "crates/pmp-macro" }
+pmp-emitter = { path = "crates/pmp-emitter" }
 
 clap = { version = "^4", features = ["derive"] }
 owo-colors = { version = "^4", features = ["supports-colors"] }

crates/pmp-core/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "pmp-core"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]
+syn  = { version = "^2", features = ["full"] }
+darling = "^0"
+proc-macro2 = "^1"

crates/pmp-core/src/attrs.rs

@@ -0,0 +1,76 @@
+use darling::FromMeta;
+
+/// Implemented by any item that carries a `Vec<syn::Attribute>`.
+///
+/// Allows `parse_pmp_attrs` to be generic over variants, fields, etc.
+pub trait HasAttrs {
+    fn attrs(&self) -> &[syn::Attribute];
+}
+
+/// Blanket impl for anything that exposes `.attrs` as a public field via a deref,
+/// covered by explicit impls below for the common syn types.
+impl HasAttrs for syn::Field {
+    fn attrs(&self) -> &[syn::Attribute] { &self.attrs }
+}
+
+impl HasAttrs for syn::Variant {
+    fn attrs(&self) -> &[syn::Attribute] { &self.attrs }
+}
+
+// ---------------------------------------------------------------------------------------------- //
+
+/// Finds a `#[{attr_name}(...)]` attribute in the given list and parses it into `T`.
+///
+/// Returns `Ok(T::default())` if no such attribute is present or
+/// a span-accurate `Err` if the attribute is present but malformed.
+///
+/// Each proc-macro crate passes its own attribute name:
+/// ```
+/// // in pmp-emitter-core:
+/// let attrs: EnumAttrs = parse_pmp_attr(&input.attrs, "pmp_emitter")?;
+///
+/// // in pmp-macro-core:
+/// let attrs: MacroAttrs = parse_pmp_attr(&input.attrs, "pmp_macro")?;
+/// ```
+pub fn parse_pmp_attr<T>(attrs: &[syn::Attribute], attr_name: &str) -> syn::Result<T>
+where
+    T: FromMeta + Default,
+{
+    match attrs.iter().find(|a| a.path().is_ident(attr_name)) 
+    {
+        None       => Ok(T::default()),
+        Some(attr) => T::from_meta(&attr.meta)
+            .map_err(|e| syn::Error::new_spanned(attr, e.to_string())),
+    }
+}
+
+/// Accumulates errors from parsing `#[{attr_name}(...)]` on a collection of items
+/// (e.g. enum variants or struct fields) into a single `syn::Error`.
+///
+/// Returns `Ok(Vec<T>)` with one parsed value per item, or `Err` containing all
+/// accumulated errors if any items failed.
+pub fn parse_pmp_attrs<T, I>(items: I, attr_name: &str) -> syn::Result<Vec<T>>
+where
+    T:    FromMeta + Default,
+    I:    IntoIterator<Item: HasAttrs>,
+{
+    let mut results: Vec<T>             = Vec::new();
+    let mut errors:  Option<syn::Error> = None;
+
+    for item in items
+    {
+        match parse_pmp_attr(item.attrs(), attr_name)
+        {
+            Ok(v)  => results.push(v),
+            Err(e) => match &mut errors {
+                None           => errors = Some(e),
+                Some(existing) => existing.combine(e),
+            },
+        }
+    }
+
+    match errors {
+        None    => Ok(results),
+        Some(e) => Err(e),
+    }
+}

crates/pmp-core/src/functions.rs

@@ -0,0 +1,49 @@
+
+pub fn pascal_to_title(s: &str) -> String
+{
+    let mut out = String::new();
+
+    for (i, ch) in s.chars().enumerate() {
+        if ch.is_uppercase() && i > 0 { out.push(' '); }
+        out.push(ch);
+    }
+
+    out
+}
+
+pub fn snake_to_title(s: &str) -> String
+{
+    s.split('_')
+        .map(|word| {
+            let mut c = word.chars();
+            match c.next() {
+                None    => String::new(),
+                Some(f) => f.to_uppercase().collect::<String>() + c.as_str(),
+            }
+        })
+        .collect::<Vec<_>>()
+        .join(" ")
+}
+
+pub fn pascal_to_snake(s: &str) -> String
+{
+    let mut out = String::with_capacity(s.len());
+    let mut prev_lower = false;
+
+    for c in s.chars()
+    {
+        if c.is_uppercase()
+        {
+            if prev_lower              { out.push('_'); }
+            for lc in c.to_lowercase() { out.push(lc); }
+            prev_lower = false;
+        }
+        else
+        {
+            prev_lower = true;
+            out.push(c);
+        }
+    }
+
+    out
+}

crates/pmp-core/src/lib.rs

@@ -0,0 +1,20 @@
+//! Shared proc-macro utilities for all `pmp-*` crates.
+//!
+//! This crate provides building blocks that are identical across every
+//! `pmp-*-core` proc-derive-macro crate. Each consumer crate still defines
+//! its own darling input structs (because `forward_attrs` bakes in a per-crate
+//! attribute name at compile time), but everything else should be imported from here.
+//!
+//! | Module    | Contents                                                         |
+//! |-----------|------------------------------------------------------------------|
+//! | `types`   | [`StrictBool`], [`StrictString`], [`StrictPath`], [`StrictExpr`] |
+//! | `helpers` | [`pascal_to_title`], [`snake_to_title`]                          |
+//! | `attr`    | [`parse_pmp_attr`], [`parse_pmp_attrs`], [`HasAttrs`]            |
+
+mod attrs;
+mod types;
+mod functions;
+
+pub use attrs::*;
+pub use types::*;
+pub use functions::*;

crates/pmp-core/src/types.rs

@@ -0,0 +1,85 @@
+use syn::{ Lit, Path };
+use darling::{ Error, Result, FromMeta };
+
+/// A boolean that must be written as `= true` or `= false`
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy)]
+pub struct StrictBool(pub bool);
+
+impl FromMeta for StrictBool
+{
+    fn from_word() -> Result<Self>
+    {
+        Err(Error::custom(
+            "expected `= true/false`, provide a boolean value"
+        ))
+    }
+
+    fn from_value(value: &Lit) -> Result<Self>
+    {
+        match value {
+            Lit::Bool(b) => Ok(StrictBool(b.value)),
+            _ => Err(Error::unexpected_lit_type(value)),
+        }
+    }
+}
+
+/// A string that must be written as `= "..."`
+#[allow(dead_code)]
+#[derive(Debug, Clone)]
+pub struct StrictString(pub String);
+
+impl FromMeta for StrictString
+{
+    fn from_word() -> Result<Self>
+    {
+        Err(Error::custom(
+            "expected `= \"...\"`, provide a string value"
+        ))
+    }
+
+    fn from_value(value: &Lit) -> Result<Self> {
+        String::from_value(value).map(StrictString)
+    }
+}
+
+/// A path that must be written as `= my_fn`
+#[allow(dead_code)]
+#[derive(Debug, Clone)]
+pub struct StrictPath(pub Path);
+
+impl FromMeta for StrictPath
+{
+    fn from_word() -> Result<Self>
+    {
+        Err(Error::custom(
+            "expected `= my_fn`, provide a function path"
+        ))
+    }
+
+    fn from_value(value: &Lit) -> Result<Self> {
+        Path::from_value(value).map(StrictPath)
+    }
+
+    fn from_expr(expr: &syn::Expr) -> Result<Self> {
+        Path::from_expr(expr).map(StrictPath)
+    }
+}
+
+/// A Rust expression that must be written as `= <expr>`
+#[derive(Debug, Clone)]
+pub struct StrictExpr(pub syn::Expr);
+
+impl FromMeta for StrictExpr
+{
+    fn from_word() -> Result<Self>
+    {
+        Err(Error::custom(
+            "expected `= <expr>`, provide an expression, e.g. `target = Target::CLASS | Target::INTERFACE`"
+        ))
+    }
+
+    fn from_expr(expr: &syn::Expr) -> Result<Self> {
+        Ok(StrictExpr(expr.clone()))
+    }
+}

crates/pmp-emitter/Cargo.toml

@@ -6,11 +6,6 @@ edition.workspace = true
 authors.workspace = true
 license-file.workspace = true
 
-[lib]
-proc-macro = true
-
 [dependencies]
-syn  = { version = "^2", features = ["full"] }
-quote = "^1"
-darling = "^0"
-proc-macro2 = "^1"
+pmp-emitter-core = { path = "crates/pmp-emitter-core" }
+pmp-emitter-misc = { path = "crates/pmp-emitter-misc" }

crates/pmp-emitter/crates/pmp-emitter-core/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "pmp-emitter-core"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[lib]
+proc-macro = true
+
+[dependencies]
+pmp-core = { path = "../../../pmp-core" }
+
+syn  = { version = "^2", features = ["full"] }
+quote = "^1"
+darling = "^0"
+proc-macro2 = "^1"

crates/pmp-emitter/crates/pmp-emitter-core/src/attrs.rs

@@ -0,0 +1,46 @@
+use darling::{ ast, FromMeta, FromVariant, FromDeriveInput };
+use pmp_core::{ StrictBool, StrictPath, StrictString };
+use syn::{ Type, Ident };
+
+#[derive(Debug, FromDeriveInput)]
+#[darling(forward_attrs(pmp_emitter))]
+pub(crate) struct EmitterInput {
+    pub ident: Ident,
+    pub data:  ast::Data<VariantReceiver, ()>,
+}
+
+#[derive(Debug, FromVariant)]
+#[darling(forward_attrs(pmp_emitter))]
+pub(crate) struct VariantReceiver {
+    pub ident:  Ident,
+    pub fields: ast::Fields<Type>,
+    pub attrs:  Vec<syn::Attribute>,
+}
+
+// ---------------------------------------------------------------------------------------------- //
+
+/// - `descriptor = "..."` - prefix shown before all variant messages (default: enum name)
+/// - `exit = true|false`  - whether to call process::exit (default: false)
+/// - `colorizer = fn`     - fn(String) -> String applied to all variants unless overridden
+#[derive(Debug, Default, FromMeta)]
+pub(crate) struct EnumAttrs {
+    #[darling(default)]
+    pub exit:       Option<StrictBool>,
+    #[darling(default)]
+    pub colorizer:  Option<StrictPath>,
+    #[darling(default)]
+    pub descriptor: Option<StrictString>,
+}
+
+/// - `message = "..."`   - error message (default: variant name as title case)
+/// - `colorizer = fn`    - optional fn(String) -> String for formatting
+/// - `exit = true|false` - overrides enum-level exit
+#[derive(Debug, Default, FromMeta)]
+pub(crate) struct VariantAttrs {
+    #[darling(default)]
+    pub exit:      Option<StrictBool>,
+    #[darling(default)]
+    pub message:   Option<StrictString>,
+    #[darling(default)]
+    pub colorizer: Option<StrictPath>,
+}

crates/pmp-emitter/crates/pmp-emitter-core/src/expand.rs

@@ -0,0 +1,103 @@
+use proc_macro2::TokenStream as TokenStream2;
+use quote::{ quote, quote_spanned };
+use pmp_core::{ self, StrictPath };
+use syn::DeriveInput;
+use darling::ast;
+
+use crate::attrs::{ EnumAttrs, EmitterInput, VariantAttrs };
+
+// ---------------------------------------------------------------------------------------------- //
+
+pub fn expand(shape: EmitterInput, raw_input: &DeriveInput) -> syn::Result<TokenStream2>
+{
+    let enum_attrs: EnumAttrs = pmp_core::parse_pmp_attr(&raw_input.attrs, "pmp_emitter")?;
+
+    let enum_ident       = &shape.ident;
+    let descriptor       = enum_attrs.descriptor
+        .map(|s| s.0)
+        .unwrap_or_else(|| pmp_core::pascal_to_title(&enum_ident.to_string()));
+    let global_exit      = enum_attrs.exit.map(|b| b.0).unwrap_or(false);
+    let global_colorizer = enum_attrs.colorizer;
+
+    let variants = shape.data.take_enum().ok_or_else(|| {
+        syn::Error::new_spanned(enum_ident, "PmpEmitter can only be derived on enums")
+    })?;
+
+    let mut errors:     Option<syn::Error> = None;
+    let mut match_arms: Vec<TokenStream2>  = Vec::with_capacity(variants.len());
+
+    for v in &variants
+    {
+        let var_ident = &v.ident;
+        let title     = pmp_core::pascal_to_title(&var_ident.to_string());
+
+        let v_attrs: VariantAttrs = match pmp_core::parse_pmp_attr(&v.attrs, "pmp_emitter")
+        {
+            Ok(a)  => a,
+            Err(e) =>
+                {
+                    match &mut errors {
+                        None           => errors = Some(e),
+                        Some(existing) => existing.combine(e),
+                    }
+                    continue;
+                }
+        };
+
+        let message     = v_attrs.message.map(|s| s.0).unwrap_or_else(|| title.clone());
+        let should_exit = v_attrs.exit.map(|b| b.0).unwrap_or(global_exit);
+
+        let header = format!("{}: {} (\"{}\")", descriptor, title, message);
+
+        let formatted_header = match v_attrs.colorizer.as_ref().or(global_colorizer.as_ref()) {
+            Some(StrictPath(path)) => quote! { #path(#header) },
+            None                   => quote! { #header.to_string() },
+        };
+
+        let exit_tokens = if should_exit { quote! { std::process::exit(1); } } else { quote! {} };
+
+        let arm = match v.fields.style
+        {
+            ast::Style::Tuple =>
+                {
+                    let pattern = if v.fields.len() == 1 { quote! { (trace) } } else { quote! { (trace, ..) } };
+
+                    quote_spanned! { var_ident.span() =>
+                    #enum_ident::#var_ident #pattern =>
+                    {
+                        println!("{}\n\n{}", #formatted_header, trace);
+                        #exit_tokens
+                    }
+                }
+                },
+            _ => quote_spanned! { var_ident.span() =>
+                #enum_ident::#var_ident =>
+                {
+                    println!("{}", #formatted_header);
+                    #exit_tokens
+                }
+            },
+        };
+
+        match_arms.push(arm);
+    }
+
+    if let Some(e) = errors { return Err(e); }
+
+    Ok(quote!
+    {
+        impl #enum_ident
+        {
+            pub fn emit(&self) {
+                match self { #(#match_arms),* }
+            }
+        }
+
+        impl ::pmp_emitter::pmp_emitter_misc::Emittable for #enum_ident
+        {
+            fn emit(&self) {
+                self.emit()
+            }
+        }
+    })
+}

crates/pmp-emitter/crates/pmp-emitter-core/src/lib.rs

@@ -0,0 +1,25 @@
+use darling::FromDeriveInput;
+use proc_macro::TokenStream;
+use syn::DeriveInput;
+
+mod attrs;
+mod expand;
+
+use attrs::EmitterInput;
+
+// ---------------------------------------------------------------------------------------------- //
+
+#[proc_macro_derive(PmpEmitter, attributes(pmp_emitter))]
+pub fn pmp_emitter(item: TokenStream) -> TokenStream
+{
+    let input = syn::parse_macro_input!(item as DeriveInput);
+
+    let shape = match EmitterInput::from_derive_input(&input) {
+        Ok(s)  => s,
+        Err(e) => return e.write_errors().into(),
+    };
+
+    expand::expand(shape, &input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}

crates/pmp-emitter/crates/pmp-emitter-misc/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "pmp-emitter-misc"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]

crates/pmp-emitter/crates/pmp-emitter-misc/src/lib.rs

@@ -0,0 +1,4 @@
+
+pub trait Emittable {
+    fn emit(&self);
+}

crates/pmp-emitter/src/lib.rs

@@ -1,185 +1,5 @@
-use quote::quote;
-use proc_macro::TokenStream;
-use syn::{ Lit, Path, Type, Ident, DeriveInput, parse_macro_input };
-use darling::{ ast, Error, Result, FromMeta, FromVariant, FromDeriveInput };
+#[doc(hidden)]
+pub extern crate pmp_emitter_misc;
 
-// ---------------------------------------------------------------------------------------------- //
-
-#[derive(Debug, FromDeriveInput)]
-#[darling(forward_attrs(pmp_emitter))]
-struct EmitterInput {
-    ident: Ident,
-    data:  ast::Data<VariantReceiver, ()>,
-}
-
-#[derive(Debug, FromVariant)]
-#[darling(forward_attrs(pmp_emitter))]
-struct VariantReceiver {
-    ident:  Ident,
-    fields: ast::Fields<Type>,
-    attrs:  Vec<syn::Attribute>,
-}
-
-// ---------------------------------------------------------------------------------------------- //
-
-#[derive(Debug, Clone, Copy)]
-struct StrictBool(bool);
-
-/// - `descriptor = "..."` - prefix shown before all variant messages (default: enum name)
-/// - `exit = true|false`  - whether to call process::exit (default: false)
-#[derive(Debug, FromMeta)]
-struct EnumAttrs {
-    #[darling(default)]
-    descriptor: Option<String>,
-    #[darling(default)]
-    exit:       Option<StrictBool>,
-}
-
-/// - `message = "..."`   - error message (default: variant name as title case)
-/// - `colorizer = fn`    - optional fn(String) -> String for formatting
-/// - `exit = true|false` - overrides enum-level exit
-#[derive(Debug, FromMeta)]
-struct VariantAttrs {
-    #[darling(default)]
-    exit:      Option<StrictBool>,
-    #[darling(default)]
-    message:   Option<String>,
-    #[darling(default)]
-    colorizer: Option<Path>,
-}
-
-// ---------------------------------------------------------------------------------------------- //
-
-impl FromMeta for StrictBool
-{
-    fn from_value(value: &Lit) -> Result<Self>
-    {
-        match value {
-            Lit::Bool(b) => Ok(StrictBool(b.value)),
-            _ => Err(Error::unexpected_lit_type(value)),
-        }
-    }
-
-    // intentionally NOT implementing from_word()
-}
-
-fn parse_pmp_attr<T: FromMeta>(attrs: &[syn::Attribute]) -> T
-where
-    T: Default,
-{
-    attrs
-        .iter()
-        .find(|a| a.path().is_ident("pmp_emitter"))
-        .map(|a| T::from_meta(&a.meta).expect("invalid pmp_emitter attribute"))
-        .unwrap_or_default()
-}
-
-impl Default for EnumAttrs {
-    fn default() -> Self {
-        Self { descriptor: None, exit: None }
-    }
-}
-
-impl Default for VariantAttrs {
-    fn default() -> Self {
-        Self { message: None, exit: None, colorizer: None }
-    }
-}
-
-// ---------------------------------------------------------------------------------------------- //
-
-fn pascal_to_title(s: &str) -> String 
-{
-    let mut out = String::new();
-
-    for (i, ch) in s.chars().enumerate() 
-    {
-        if ch.is_uppercase() && i > 0 { out.push(' '); }
-        out.push(ch);
-    }
-
-    out
-}
-
-// ---------------------------------------------------------------------------------------------- //
-
-#[proc_macro_derive(PmpEmitter, attributes(pmp_emitter))]
-pub fn pmp_emitter(item: TokenStream) -> TokenStream
-{
-    let input = parse_macro_input!(item as DeriveInput);
-
-    // parse enum shape
-    let shape = match EmitterInput::from_derive_input(&input) {
-        Ok(a)  => a,
-        Err(e) => return e.write_errors().into(),
-    };
-
-    // parse enum-level #[pmp_emitter(...)] directly from the raw attrs
-    let enum_attrs: EnumAttrs = parse_pmp_attr(&input.attrs);
-
-    let enum_ident  = &shape.ident;
-    let descriptor  = enum_attrs.descriptor
-        .unwrap_or_else(|| pascal_to_title(&enum_ident.to_string()));
-    let global_exit = enum_attrs.exit.map(|b| b.0).unwrap_or(false);
-
-    let variants = shape
-        .data
-        .take_enum()
-        .expect("PmpEmitter can only be derived on enums");
-
-    let match_arms = variants.iter().map(|v|
-        {
-            let var_ident = &v.ident;
-            let title     = pascal_to_title(&var_ident.to_string());
-
-            // parse variant-level #[pmp_emitter(...)] from the variant's raw attrs
-            let vattrs: VariantAttrs = parse_pmp_attr(&v.attrs);
-
-            let message     = vattrs.message.unwrap_or_else(|| title.clone());
-            let should_exit = vattrs.exit.map(|b| b.0).unwrap_or(global_exit);
-
-            // ┌─ Output format ───────────────────────────────┐
-            // │  {descriptor}: {Variant Title} ("{message}")  │
-            // │                                               │
-            // │  {stacktrace}                                 │
-            // └───────────────────────────────────────────────┘
-            let header = format!("{}: {} (\"{}\")", descriptor, title, message);
-
-            let formatted_header = match &vattrs.colorizer
-            {
-                Some(path) => quote! { #path(#header) },
-                None       => quote! { #header.to_string() },
-            };
-
-            let exit_tokens = if should_exit { quote! { std::process::exit(1); } } else { quote! {} };
-
-            match v.fields.style
-            {
-                ast::Style::Tuple => quote! {
-                #enum_ident::#var_ident(trace) =>
-                {
-                    println!("{}\n\n{}", #formatted_header, trace);
-                    #exit_tokens
-                }
-            },
-                _ => quote! {
-                #enum_ident::#var_ident =>
-                {
-                    println!("{}", #formatted_header);
-                    #exit_tokens
-                }
-            },
-            }
-        });
-
-    quote! {
-        impl #enum_ident
-        {
-            pub fn emit(&self) {
-                match self {
-                    #(#match_arms),*
-                }
-            }
-        }
-    }.into()
-}
+pub use pmp_emitter_misc::Emittable;
+pub use pmp_emitter_core::PmpEmitter;

crates/pmp-macro/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "pmp-macro"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]
+pmp-macro-core = { path = "crates/pmp-macro-core" }
+pmp-macro-misc = { path = "crates/pmp-macro-misc" }

crates/pmp-macro/crates/pmp-macro-core/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "pmp-macro-core"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[lib]
+proc-macro = true
+
+[dependencies]
+pmp-core = { path = "../../../pmp-core" }
+pmp-macro-misc = { path = "../pmp-macro-misc" }
+
+syn  = { version = "^2", features = ["full"] }
+quote = "^1"
+darling = "^0"
+proc-macro2 = "^1"

crates/pmp-macro/crates/pmp-macro-core/src/attrs.rs

@@ -0,0 +1,49 @@
+use pmp_core::{ StrictBool, StrictExpr, StrictString };
+use darling::{ ast, FromField, FromDeriveInput };
+use syn::{ Type, Ident };
+
+/// - `name = "..."`     - PHP attribute name (default: struct name)
+/// - `target = <expr>`  - which PHP constructs may use this attribute (default: Target::ALL)
+/// - `docs = "..."`     - description for diagnostics and generated docs
+#[derive(Debug, FromDeriveInput)]
+#[darling(attributes(pmp_macro), forward_attrs(allow, doc, cfg))]
+pub struct MacroInput {
+    pub ident: Ident,
+    pub data:  ast::Data<darling::util::Ignored, FieldInput>,
+
+    #[darling(default)]
+    pub name:   Option<StrictString>,
+    #[darling(default)]
+    pub target: Option<StrictExpr>,
+    #[darling(default)]
+    pub docs:   Option<StrictString>,
+}
+
+/// - `php_type = "..."` - PHP type hint, e.g. `"class-string[]"` (required)
+/// - `default = "..."`  - PHP default value, e.g. `"[]"`
+/// - `required = bool`  - overrides required inference
+#[derive(Debug, FromField)]
+#[darling(attributes(param))]
+pub struct FieldInput {
+    pub ident: Option<Ident>,
+    #[allow(dead_code)]
+    pub ty:    Type,
+
+    #[darling(default)]
+    pub php_type: Option<StrictString>,
+    #[darling(default)]
+    pub default:  Option<StrictString>,
+    #[darling(default)]
+    pub required: Option<StrictBool>,
+}
+
+impl FieldInput
+{
+    pub fn is_param(&self) -> bool {
+        self.php_type.is_some()
+    }
+
+    pub fn is_required(&self) -> bool {
+        self.required.map(|b| b.0).unwrap_or(self.default.is_none())
+    }
+}

crates/pmp-macro/crates/pmp-macro-core/src/expand.rs

@@ -0,0 +1,129 @@
+use quote::{ format_ident, quote, quote_spanned };
+use proc_macro2::TokenStream as TokenStream2;
+
+use crate::attrs::MacroInput;
+
+fn rewrite_bitor_target_expr(expr: syn::Expr) -> syn::Expr
+{
+    match expr
+    {
+        syn::Expr::Binary(mut bin) if matches!(bin.op, syn::BinOp::BitOr(_)) => {
+            bin.left  = Box::new(rewrite_bitor_target_expr(*bin.left));
+            bin.right = Box::new(rewrite_bitor_target_expr(*bin.right));
+            syn::Expr::Binary(bin)
+        }
+
+        other => {
+            syn::parse_quote! { (#other).bits() }
+        }
+    }
+}
+
+pub fn expand(parsed: MacroInput) -> syn::Result<TokenStream2>
+{
+    let struct_ident = &parsed.ident;
+
+    let fields = parsed.data.take_struct().ok_or_else(|| {
+        syn::Error::new_spanned(struct_ident, "PmpMacro can only be derived for structs")
+    })?;
+
+    let attr_name: String = parsed.name
+        .map(|s| s.0)
+        .unwrap_or_else(|| struct_ident.to_string());
+
+    let target_expr: syn::Expr = parsed.target
+        .map(|e| rewrite_bitor_target_expr(e.0))
+        .unwrap_or_else(|| syn::parse_quote! { ::pmp_macro::Target::ALL.bits() });
+
+    let docs: String = parsed.docs.map(|s| s.0).unwrap_or_default();
+
+    let mut param_tokens: Vec<TokenStream2> = Vec::new();
+    let mut errors:       Option<syn::Error> = None;
+
+    for field in fields.iter().filter(|f| f.is_param())
+    {
+        let span       = field.ident.as_ref().map(|i| i.span()).unwrap_or_else(|| struct_ident.span());
+        let field_name = field.ident.as_ref().map(|i| i.to_string()).unwrap_or_default();
+
+        let php_type = match &field.php_type
+        {
+            Some(s) => s.0.clone(),
+            None    =>
+                {
+                    let e = syn::Error::new(
+                        span,
+                        format!("field `{field_name}` has #[param] but is missing `php_type = \"...\"`"),
+                    );
+                    match &mut errors {
+                        None           => errors = Some(e),
+                        Some(existing) => existing.combine(e),
+                    }
+                    continue;
+                }
+        };
+
+        let required       = field.is_required();
+        let default_tokens = match field.default.as_ref().map(|s| s.0.as_str()) {
+            Some(d) => quote! { Some(#d) },
+            None    => quote! { None },
+        };
+
+        param_tokens.push(quote_spanned! { span =>
+            ::pmp_macro::ParamDescriptor {
+                name:     #field_name,
+                php_type: #php_type,
+                required: #required,
+                default:  #default_tokens,
+            }
+        });
+    }
+
+    if let Some(e) = errors { return Err(e); }
+
+    let snaked_ident = pmp_core::pascal_to_snake(struct_ident.to_string().as_str());
+    let mod_ident    = format_ident!("__pmp_macro_impl_{}", snaked_ident);
+    let handler      = quote! { super::#struct_ident };
+
+    Ok(quote!
+    {
+        #[doc(hidden)]
+        mod #mod_ident
+        {
+            use ::pmp_macro::{
+                 AnalyzeFn, MacroDescriptor, MacroRegistration,
+                 ParamDescriptor, Target, TransformFn, PmpMacro,
+            };
+
+            static PARAMS: &[ParamDescriptor] = &[ #(#param_tokens),* ];
+
+            static DESCRIPTOR: MacroDescriptor = MacroDescriptor {
+                name:        #attr_name,
+                target_bits: #target_expr,
+                docs:        #docs,
+                params:      PARAMS,
+            };
+
+            fn analyze(
+                ctx:  &::pmp_macro::MacroContext,
+                attr: &::pmp_macro::ResolvedAttr,
+                node: &::pmp_macro::AttributedNode,
+            ) -> ::std::vec::Vec<::pmp_macro::Diagnostic>
+            {
+                <#handler as PmpMacro>::analyze(&::std::default::Default::default(), ctx, attr, node)
+            }
+
+            fn transform(
+                ctx:  &::pmp_macro::MacroContext,
+                attr: &::pmp_macro::ResolvedAttr,
+                node: &::pmp_macro::AttributedNode,
+            ) -> ::std::vec::Vec<::pmp_macro::Rewrite>
+            {
+                <#handler as PmpMacro>::transform(&::std::default::Default::default(), ctx, attr, node)
+            }
+
+            ::pmp_macro::inventory::submit! {
+                MacroRegistration::new(&DESCRIPTOR, analyze, transform)
+            }
+        }
+    })
+}

crates/pmp-macro/crates/pmp-macro-core/src/lib.rs

@@ -0,0 +1,55 @@
+use darling::FromDeriveInput;
+use proc_macro::TokenStream;
+use syn::DeriveInput;
+
+mod attrs;
+mod expand;
+
+use attrs::MacroInput;
+
+/// Derives registration boilerplate for a PHP macro attribute handler.
+///
+/// #### Struct-level attributes (`#[pmp_macro(...)]`)
+///
+/// | Key        | Type          | Default          | Description                                  |
+/// |------------|---------------|------------------|----------------------------------------------|
+/// | `name`     | `= "..."`     | Struct name      | PHP attribute name to match against          |
+/// | `target`   | `= <expr>`    | `Target::ALL`    | Which PHP constructs may use this attribute  |
+/// | `docs`     | `= "..."`     | `""`             | Description for diagnostics and generated docs |
+///
+/// #### Field-level attributes (`#[param(...)]`)
+///
+/// Fields without `#[param(...)]` are ignored - they are treated as handler
+/// implementation details, not PHP constructor parameters.
+///
+/// | Key        | Type      | Default           | Description                              |
+/// |------------|-----------|-------------------|------------------------------------------|
+/// | `php_type` | `= "..."` | *(required)*      | PHP type hint, e.g. `"class-string[]"`   |
+/// | `default`  | `= "..."` | `None`            | PHP default value, e.g. `"[]"`          |
+/// | `required` | `= bool`  | inferred          | Overrides required inference             |
+///
+/// #### What is generated
+///
+/// - A hidden module containing a `static MacroDescriptor` and `static [ParamDescriptor]`
+/// - Two free functions delegating to the handler's `PmpMacro::analyze` / `::transform`
+/// - An `inventory::submit!` registration wiring it all together
+///
+/// #### Requirements
+///
+/// - The struct must implement [`pmp_macro_misc::PmpMacro`] (user-written)
+/// - The struct must implement [`Default`] (needed to construct a handler instance
+///   inside the generated delegation functions)
+#[proc_macro_derive(PmpMacro, attributes(pmp_macro, param))]
+pub fn pmp_macro_derive(item: TokenStream) -> TokenStream
+{
+    let input = syn::parse_macro_input!(item as DeriveInput);
+
+    let parsed = match MacroInput::from_derive_input(&input) {
+        Ok(p)  => p,
+        Err(e) => return e.write_errors().into(),
+    };
+
+    expand::expand(parsed)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}

crates/pmp-macro/crates/pmp-macro-misc/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "pmp-macro-misc"
+version = "1.0.0"
+
+edition.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]
+bitflags  = "^2"
+inventory = "^0"

crates/pmp-macro/crates/pmp-macro-misc/src/context.rs

@@ -0,0 +1,45 @@
+// ---------------------------------------------------------------------------------------------- //
+// Mago-facing placeholders                                                                       //
+//                                                                                                //
+// These types will wrap or re-export mago's AST / symbol / source types once the                 //
+// integration surface is understood. For now they are empty structs so the trait                 //
+// and derive can be written against concrete type names without a mago dependency.               //
+// ---------------------------------------------------------------------------------------------- //
+
+/// Global preprocessor state passed to every handler invocation.
+///
+/// Will hold references to mago's parsed file set, resolved symbol table,
+/// and any cross-file index needed for macros like `#[Sealed]` that must
+/// scan the entire project.
+///
+/// TODO: replace with real mago types.
+#[non_exhaustive]
+pub struct MacroContext;
+
+/// The PHP AST node that carries the attribute being processed, together
+/// with the specific attribute instance (which macro it is, its position).
+///
+/// TODO: replace with real mago node types.
+#[non_exhaustive]
+pub struct AttributedNode;
+
+/// The parsed and type-resolved arguments supplied to the attribute.
+///
+/// e.g. for `#[Sealed([Success::class, Failure::class])]` this would
+/// expose the two resolved class names as typed Rust values.
+///
+/// TODO: replace with real resolved argument types.
+#[non_exhaustive]
+pub struct ResolvedAttr;
+
+/// A single source-level diagnostic emitted by a macro handler.
+///
+/// TODO: decide between a custom type or wrapping mago's / miette's diagnostic type.
+#[non_exhaustive]
+pub struct Diagnostic;
+
+/// A rewrite instruction produced by `PmpMacro::transform`.
+///
+/// TODO: decide between text-span replacement or typed AST mutation depending on what mago exposes.
+#[non_exhaustive]
+pub struct Rewrite;

crates/pmp-macro/crates/pmp-macro-misc/src/descriptor.rs

@@ -0,0 +1,26 @@
+use crate::target::Target;
+
+#[derive(Debug, Clone, Copy)]
+pub struct ParamDescriptor {
+    pub name:     &'static str,
+    pub php_type: &'static str,
+    pub required: bool,
+    pub default:  Option<&'static str>,
+}
+
+#[derive(Debug)]
+pub struct MacroDescriptor {
+    pub name:        &'static str,
+    /// Raw bitflags value - use `.target()` to get a `Target`.
+    /// Stored as `u16` so the static initializer remains `const`.
+    pub target_bits: u16,
+    pub docs:        &'static str,
+    pub params:      &'static [ParamDescriptor],
+}
+
+impl MacroDescriptor
+{
+    pub fn target(&self) -> Target {
+        Target::from_bits_truncate(self.target_bits)
+    }
+}

crates/pmp-macro/crates/pmp-macro-misc/src/lib.rs

@@ -0,0 +1,23 @@
+//! Shared types, traits, and registration machinery for `pmp-macro`.
+//!
+//! # Crate layout
+//!
+//! | Module       | Contents                                                        |
+//! |--------------|-----------------------------------------------------------------|
+//! | `target`     | [`Target`] bitflags for PHP attribute target sites              |
+//! | `descriptor` | [`MacroDescriptor`] and [`ParamDescriptor`] - static metadata   |
+//! | `context`    | [`MacroContext`], [`AttributedNode`], [`ResolvedAttr`], etc.    |
+//! | `traits`     | [`PmpMacro`] trait, [`MacroRegistration`], [`MacroRegistry`]    |
+
+mod target;
+mod traits;
+mod context;
+mod descriptor;
+
+#[doc(hidden)]
+pub use inventory;
+
+pub use target::*;
+pub use traits::*;
+pub use context::*;
+pub use descriptor::*;

crates/pmp-macro/crates/pmp-macro-misc/src/target.rs

@@ -0,0 +1,75 @@
+use std::fmt::{ Display, Formatter };
+use bitflags::bitflags;
+
+bitflags!
+{
+    /// The PHP construct(s) that a macro attribute is permitted to annotate.
+    ///
+    /// Mirrors PHP's `Attribute::TARGET_*` constants. A macro may target
+    /// multiple sites by OR-ing flags together:
+    ///
+    /// ```
+    /// let target = Target::CLASS | Target::INTERFACE;
+    /// ```
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    pub struct Target: u16
+    {
+        const CLASS     = 1 << 0;
+        const INTERFACE = 1 << 1;
+        const TRAIT     = 1 << 2;
+        const ENUM      = 1 << 3;
+        const METHOD    = 1 << 4;
+        const FUNCTION  = 1 << 5;
+        const PROPERTY  = 1 << 6;
+        const CONSTANT  = 1 << 7;
+        const PARAMETER = 1 << 8;
+
+        /// Convenience: any class-like construct.
+        const ANY_CLASS_LIKE = Self::CLASS.bits()
+            | Self::INTERFACE.bits()
+            | Self::TRAIT.bits()
+            | Self::ENUM.bits();
+
+        /// Convenience: any callable construct.
+        const ANY_CALLABLE = Self::METHOD.bits()
+            | Self::FUNCTION.bits();
+
+        /// Convenience: all targets.
+        const ALL = u16::MAX;
+    }
+}
+
+impl Display for Target
+{
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result
+    {
+        let mut first = true;
+
+        macro_rules! write_flag
+        {
+            ($flag:ident) =>
+            {
+                if self.contains(Target::$flag)
+                {
+                    if !first { write!(f, " | ")?; }
+                    write!(f, "Target::{}", stringify!($flag))?;
+                    first = false;
+                }
+            };
+        }
+
+        write_flag!(CLASS);
+        write_flag!(INTERFACE);
+        write_flag!(TRAIT);
+        write_flag!(ENUM);
+        write_flag!(METHOD);
+        write_flag!(FUNCTION);
+        write_flag!(PROPERTY);
+        write_flag!(CONSTANT);
+        write_flag!(PARAMETER);
+
+        if first { write!(f, "Target::ALL")?; }
+
+        Ok(())
+    }
+}

crates/pmp-macro/crates/pmp-macro-misc/src/traits.rs

@@ -0,0 +1,146 @@
+use std::{
+    sync::OnceLock,
+    collections::HashMap
+};
+
+use crate::{
+    descriptor::MacroDescriptor,
+    context::{ Rewrite, Diagnostic, ResolvedAttr, MacroContext, AttributedNode }
+};
+
+// --------------------------------------------------------------------------------------------- //
+
+/// The handler trait implemented by each PHP macro attribute struct.
+///
+/// The two handler methods have default no-op
+/// implementations so that analysis-only and transform-only macros only need
+/// to override what they actually do.
+///
+/// The trait is object-safe (`&self`, no generics), so the registry can store
+/// `Box<dyn PmpMacro>` without knowing concrete types.
+pub trait PmpMacro: Send + Sync
+{
+    /// Analyse the attributed PHP node and emit diagnostics.
+    ///
+    /// Called during the analysis pass. Returning an empty `Vec` means no
+    /// issues were found. The default implementation is a no-op.
+    #[allow(unused_variables)]
+    fn analyze(
+        &self,
+        ctx:  &MacroContext,
+        attr: &ResolvedAttr,
+        node: &AttributedNode,
+    ) -> Vec<Diagnostic> { vec![] }
+
+    /// Produce rewrite instructions for the attributed PHP node.
+    ///
+    /// Called during the transform pass, after all analysis is complete.
+    /// The default implementation is a no-op.
+    #[allow(unused_variables)]
+    fn transform(
+        &self,
+        ctx:  &MacroContext,
+        attr: &ResolvedAttr,
+        node: &AttributedNode,
+    ) -> Vec<Rewrite> { vec![] }
+}
+
+// --------------------------------------------------------------------------------------------- //
+
+/// Type alias for the analyze handler function pointer.
+pub type AnalyzeFn   = fn(&MacroContext, &ResolvedAttr, &AttributedNode) -> Vec<Diagnostic>;
+/// Type alias for the transform handler function pointer.
+pub type TransformFn = fn(&MacroContext, &ResolvedAttr, &AttributedNode) -> Vec<Rewrite>;
+
+/// An entry in the global macro registry, submitted via `inventory::submit!`.
+///
+/// Stores static metadata alongside fn pointers that delegate to the
+/// handler struct's `PmpMacro` impl, avoiding the need for `dyn` dispatch.
+///
+/// Generated via `#[derive(PmpMacro)]`
+pub struct MacroRegistration {
+    /// Static metadata for this macro — attribute name, targets, params, docs.
+    pub descriptor: &'static MacroDescriptor,
+    /// Delegates to `<Handler as PmpMacro>::analyze`.
+    pub analyze:    AnalyzeFn,
+    /// Delegates to `<Handler as PmpMacro>::transform`.
+    pub transform:  TransformFn,
+}
+
+impl MacroRegistration
+{
+    pub const fn new(
+        descriptor: &'static MacroDescriptor,
+        analyze:    AnalyzeFn,
+        transform:  TransformFn,
+    ) -> Self
+    {
+        Self { descriptor, analyze, transform }
+    }
+}
+
+inventory::collect!(MacroRegistration);
+
+// --------------------------------------------------------------------------------------------- //
+
+/// Validated, deduplicated view of the global macro registry.
+/// Built once on first access via [`registry()`] and cached for the process lifetime.
+pub struct MacroRegistry {
+    /// Handlers keyed by attribute name for O(1) lookup during processing.
+    handlers: HashMap<&'static str, &'static MacroRegistration>,
+}
+
+static REGISTRY: OnceLock<MacroRegistry> = OnceLock::new();
+
+impl MacroRegistry
+{
+    /// Returns the global macro registry, validating and building it on first call.
+    ///
+    /// Deduplication is checked here — if two macros share the same attribute name
+    /// this will panic with a descriptive message. Subsequent calls are free
+    /// (just an atomic load from the `OnceLock`).
+    ///
+    /// This is the only intended way to access registered macros. Direct use of
+    /// `inventory::iter::<MacroRegistration>` bypasses dedup and should be avoided.
+    pub fn registry() -> &'static MacroRegistry {
+        REGISTRY.get_or_init(MacroRegistry::build)
+    }
+
+    fn build() -> Self
+    {
+        let mut handlers: HashMap<&'static str, &'static MacroRegistration> = HashMap::new();
+
+        for reg in inventory::iter::<MacroRegistration>
+        {
+            let name = reg.descriptor.name;
+
+            if handlers.insert(name, reg).is_some() {
+                panic!(
+                    "duplicate PmpMacro registration: attribute name \"{name}\" is \
+                     registered more than once - check your macro definitions"
+                );
+            }
+        }
+
+        Self { handlers }
+    }
+
+    /// Look up a registered macro by its PHP attribute name.
+    pub fn get(&self, name: &str) -> Option<&'static MacroRegistration> {
+        self.handlers.get(name).copied()
+    }
+
+    /// Iterate over all registered macros.
+    pub fn iter(&self) -> impl Iterator<Item = &'static MacroRegistration> {
+        self.handlers.values().copied()
+    }
+
+    /// The number of registered macros.
+    pub fn len(&self) -> usize {
+        self.handlers.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.handlers.is_empty()
+    }
+}

crates/pmp-macro/src/lib.rs

@@ -0,0 +1,5 @@
+#[doc(hidden)]
+pub extern crate pmp_macro_misc;
+
+pub use pmp_macro_misc::*;
+pub use pmp_macro_core::*;