Prepare display spec scaffolding for format args

CHANGELOG.md

@@ -6,6 +6,14 @@ All notable changes to this project will be documented in this file.
 ### Added
 - _Nothing yet._
 
+## [0.5.14] - 2025-10-06
+
+### Added
+- Prepared the derive input structures for future `format_args!` support by
+  introducing display specification variants for templates with arguments and
+  `fmt = <path>` handlers, along with `FormatArgsSpec`/`FormatArg` metadata
+  scaffolding.
+
 ## [0.5.13] - 2025-10-05
 
 ### Documentation

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "masterror"
-version = "0.5.13"
+version = "0.5.14"
 rust-version = "1.90"
 edition = "2024"
 license = "MIT OR Apache-2.0"
@@ -49,7 +49,7 @@ turnkey = []
 openapi = ["dep:utoipa"]
 
 [workspace.dependencies]
-masterror-derive = { version = "0.1.5", path = "masterror-derive" }
+masterror-derive = { version = "0.1.6", path = "masterror-derive" }
 masterror-template = { version = "0.1.4", path = "masterror-template" }
 
 [dependencies]

README.md

@@ -29,9 +29,9 @@ Stable categories, conservative HTTP mapping, no `unsafe`.
 
 ~~~toml
 [dependencies]
-masterror = { version = "0.5.13", default-features = false }
+masterror = { version = "0.5.14", default-features = false }
 # or with features:
-# masterror = { version = "0.5.13", features = [
+# masterror = { version = "0.5.14", features = [
 #   "axum", "actix", "openapi", "serde_json",
 #   "sqlx", "sqlx-migrate", "reqwest", "redis",
 #   "validator", "config", "tokio", "multipart",
@@ -66,10 +66,10 @@ masterror = { version = "0.5.13", default-features = false }
 ~~~toml
 [dependencies]
 # lean core
-masterror = { version = "0.5.13", default-features = false }
+masterror = { version = "0.5.14", default-features = false }
 
 # with Axum/Actix + JSON + integrations
-# masterror = { version = "0.5.13", features = [
+# masterror = { version = "0.5.14", features = [
 #   "axum", "actix", "openapi", "serde_json",
 #   "sqlx", "sqlx-migrate", "reqwest", "redis",
 #   "validator", "config", "tokio", "multipart",
@@ -383,13 +383,13 @@ assert_eq!(resp.status, 401);
 Minimal core:
 
 ~~~toml
-masterror = { version = "0.5.13", default-features = false }
+masterror = { version = "0.5.14", default-features = false }
 ~~~
 
 API (Axum + JSON + deps):
 
 ~~~toml
-masterror = { version = "0.5.13", features = [
+masterror = { version = "0.5.14", features = [
   "axum", "serde_json", "openapi",
   "sqlx", "reqwest", "redis", "validator", "config", "tokio"
 ] }
@@ -398,7 +398,7 @@ masterror = { version = "0.5.13", features = [
 API (Actix + JSON + deps):
 
 ~~~toml
-masterror = { version = "0.5.13", features = [
+masterror = { version = "0.5.14", features = [
   "actix", "serde_json", "openapi",
   "sqlx", "reqwest", "redis", "validator", "config", "tokio"
 ] }

README.ru.md

@@ -27,9 +27,9 @@
 
 ~~~toml
 [dependencies]
-masterror = { version = "0.5.13", default-features = false }
+masterror = { version = "0.5.14", default-features = false }
 # или с нужными интеграциями
-# masterror = { version = "0.5.13", features = [
+# masterror = { version = "0.5.14", features = [
 #   "axum", "actix", "openapi", "serde_json",
 #   "sqlx", "sqlx-migrate", "reqwest", "redis",
 #   "validator", "config", "tokio", "multipart",

masterror-derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "masterror-derive"
 rust-version = "1.90"
-version = "0.1.5"
+version = "0.1.6"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/RAprogramm/masterror"

masterror-derive/src/display.rs

@@ -1,7 +1,7 @@
 use masterror_template::template::{TemplateFormatter, TemplateFormatterKind};
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
-use syn::Error;
+use syn::{Error, spanned::Spanned};
 
 use crate::{
     input::{
@@ -25,9 +25,17 @@ fn expand_struct(input: &ErrorInput, data: &StructData) -> Result<TokenStream, E
         DisplaySpec::Transparent {
             ..
         } => render_struct_transparent(&data.fields),
-        DisplaySpec::Template(template) => render_template(template, |placeholder| {
+        DisplaySpec::Template(template)
+        | DisplaySpec::TemplateWithArgs {
+            template, ..
+        } => render_template(template, |placeholder| {
             struct_placeholder_expr(&data.fields, placeholder)
-        })?
+        })?,
+        DisplaySpec::FormatterPath {
+            path, ..
+        } => {
+            return Err(Error::new(path.span(), "`fmt = ...` is not supported yet"));
+        }
     };
 
     let ident = &input.ident;
@@ -81,7 +89,13 @@ fn render_variant(variant: &VariantData) -> Result<TokenStream, Error> {
         DisplaySpec::Transparent {
             ..
         } => render_variant_transparent(variant),
-        DisplaySpec::Template(template) => render_variant_template(variant, template)
+        DisplaySpec::Template(template)
+        | DisplaySpec::TemplateWithArgs {
+            template, ..
+        } => render_variant_template(variant, template),
+        DisplaySpec::FormatterPath {
+            path, ..
+        } => Err(Error::new(path.span(), "`fmt = ...` is not supported yet"))
     }
 }
 

masterror-derive/src/error_trait.rs

@@ -81,7 +81,13 @@ fn struct_source_body(fields: &Fields, display: &DisplaySpec) -> TokenStream {
                 quote! { None }
             }
         }
-        DisplaySpec::Template(_) => {
+        DisplaySpec::Template(_)
+        | DisplaySpec::TemplateWithArgs {
+            ..
+        }
+        | DisplaySpec::FormatterPath {
+            ..
+        } => {
             if let Some(field) = fields.iter().find(|field| field.attrs.has_source()) {
                 let member = &field.member;
                 field_source_expr(quote!(self.#member), quote!(&self.#member), &field.ty)
@@ -97,7 +103,13 @@ fn variant_source_arm(variant: &VariantData) -> TokenStream {
         DisplaySpec::Transparent {
             ..
         } => variant_transparent_source(variant),
-        DisplaySpec::Template(_) => variant_template_source(variant)
+        DisplaySpec::Template(_)
+        | DisplaySpec::TemplateWithArgs {
+            ..
+        }
+        | DisplaySpec::FormatterPath {
+            ..
+        } => variant_template_source(variant)
     }
 }
 

masterror-derive/src/input.rs

@@ -1,7 +1,7 @@
-use proc_macro2::Span;
+use proc_macro2::{Span, TokenStream};
 use syn::{
-    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Field as SynField,
-    Fields as SynFields, GenericArgument, Ident, LitStr, spanned::Spanned
+    Attribute, Data, DataEnum, DataStruct, DeriveInput, Error, Expr, Field as SynField,
+    Fields as SynFields, GenericArgument, Ident, LitStr, Path, spanned::Spanned
 };
 
 use crate::template_support::{DisplayTemplate, TemplateIdentifierSpec, parse_display_template};
@@ -21,16 +21,20 @@ pub enum ErrorData {
 
 #[derive(Debug)]
 pub struct StructData {
-    pub fields:  Fields,
-    pub display: DisplaySpec
+    pub fields:      Fields,
+    pub display:     DisplaySpec,
+    #[allow(dead_code)]
+    pub format_args: FormatArgsSpec
 }
 
 #[derive(Debug)]
 pub struct VariantData {
-    pub ident:   Ident,
-    pub fields:  Fields,
-    pub display: DisplaySpec,
-    pub span:    Span
+    pub ident:       Ident,
+    pub fields:      Fields,
+    pub display:     DisplaySpec,
+    #[allow(dead_code)]
+    pub format_args: FormatArgsSpec,
+    pub span:        Span
 }
 
 #[derive(Debug)]
@@ -245,8 +249,43 @@ impl FieldAttrs {
 
 #[derive(Debug)]
 pub enum DisplaySpec {
-    Transparent { attribute: Box<Attribute> },
-    Template(DisplayTemplate)
+    Transparent {
+        attribute: Box<Attribute>
+    },
+    Template(DisplayTemplate),
+    #[allow(dead_code)]
+    TemplateWithArgs {
+        template: DisplayTemplate,
+        args:     FormatArgsSpec
+    },
+    #[allow(dead_code)]
+    FormatterPath {
+        path: Path,
+        args: FormatArgsSpec
+    }
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Default)]
+pub struct FormatArgsSpec {
+    pub args: Vec<FormatArg>
+}
+
+#[allow(dead_code)]
+#[derive(Debug)]
+pub struct FormatArg {
+    pub tokens: TokenStream,
+    pub expr:   Expr,
+    pub kind:   FormatBindingKind,
+    pub span:   Span
+}
+
+#[allow(dead_code)]
+#[derive(Debug)]
+pub enum FormatBindingKind {
+    Named(Ident),
+    Positional(usize),
+    Implicit
 }
 
 pub fn parse_input(input: DeriveInput) -> Result<ErrorInput, Error> {
@@ -300,7 +339,8 @@ fn parse_struct(
 
     Ok(ErrorData::Struct(Box::new(StructData {
         fields,
-        display
+        display,
+        format_args: FormatArgsSpec::default()
     })))
 }
 
@@ -348,6 +388,7 @@ fn parse_variant(variant: syn::Variant, errors: &mut Vec<Error>) -> Result<Varia
         ident: variant.ident,
         fields,
         display,
+        format_args: FormatArgsSpec::default(),
         span
     })
 }