Replace proc-macro-error proc-macro2-diagnostics

Replaces the use of the 'proc-macro-error' with 'proc-macro2-diagnostics'.
The former seems to be unmaintained and is no longer updating its dependencies, which is a problem for downstream crates.

Cargo.toml

@@ -17,19 +17,20 @@ exclude = ["rustfmt.toml", ".gitignore", "README.md", "CHANGELOG.md"]
 proc-macro = true
 
 [dependencies]
-proc-macro-error = { version = "1.0.4", optional = true }
+proc-macro2-diagnostics = { version = "0.10", optional = true }
+proc-macro2 = { version = "1.0.85", optional = true }
 heck = { version = "0.4.0", optional = true }
 
 [dev-dependencies]
-duplicate_macrotest = "1.0.3"
+duplicate_macrotest = "1.0.5"
 doc-comment = "0.3.3"
 serde = "1.0.105, < 1.0.157" # Needed because macrotest's cargo.toml uses 1.0 however fails with < 1.0.105 and >= 1.0.157 (because it uses syn v2)
 regex = "1.6.0"
 rustversion = "1.0.7"
 
 [features]
 default = ["pretty_errors", "module_disambiguation"]
-pretty_errors = ["proc-macro-error"]
+pretty_errors = ["dep:proc-macro2-diagnostics", "dep:proc-macro2"]
 module_disambiguation = ["heck"]
 fail-on-warnings = [] # Forces compilation to fail if any warnings are given. Used in CI.
 

src/error.rs

@@ -1,4 +1,8 @@
 use proc_macro::Span;
+#[cfg(feature = "pretty_errors")]
+use proc_macro2::Span as Span2;
+#[cfg(feature = "pretty_errors")]
+use proc_macro2_diagnostics::{Diagnostic, Level};
 
 /// Used to report errors.
 ///
@@ -69,29 +73,36 @@ impl Error
 		self
 	}
 
-	/// Returns the source span of the error and a full message including a
-	/// potential hint (if applicable).
-	///
-	/// If a span wasn't specified, returns the call site span.
-	pub fn extract(self) -> (Span, String)
+	/// Returns the source span of the error
+	/// (or a stub value if the `pretty_errors` feature is disabled).
+	pub fn get_span(&self) -> Span
 	{
 		#[cfg(feature = "pretty_errors")]
 		{
-			(
-				self.span,
-				if !self.hint.is_empty()
-				{
-					self.msg + "\n" + self.hint.as_str()
-				}
-				else
-				{
-					self.msg
-				},
-			)
+			self.span
 		}
 		#[cfg(not(feature = "pretty_errors"))]
 		{
-			(Span::call_site(), self.msg)
+			Span::call_site()
+		}
+	}
+
+	/// Returns the message of the error.
+	#[cfg(not(feature = "pretty_errors"))]
+	pub fn into_panic_message(self) -> String
+	{
+		self.msg
+	}
+
+	#[cfg(feature = "pretty_errors")]
+	/// Converts the error into a [`Diagnostic`] ready for emitting.
+	pub fn into_diagnostic(self) -> Diagnostic
+	{
+		let mut diagnostic = Diagnostic::spanned(Span2::from(self.span), Level::Error, self.msg);
+		if !self.hint.is_empty()
+		{
+			diagnostic = diagnostic.help(self.hint);
 		}
+		diagnostic
 	}
 }

src/lib.rs

@@ -720,8 +720,6 @@ use crate::{
 };
 use parse::*;
 use proc_macro::{Delimiter, Group, Ident, Span, TokenStream};
-#[cfg(feature = "pretty_errors")]
-use proc_macro_error::{abort, proc_macro_error};
 use std::{collections::HashMap, iter::empty};
 use substitute::*;
 
@@ -1007,13 +1005,12 @@ use substitute::*;
 /// substitutions groups), must all be defined at the beginning, and aren't
 /// usable in the invocation itself but only in the code being duplicated.
 #[proc_macro_attribute]
-#[cfg_attr(feature = "pretty_errors", proc_macro_error)]
 pub fn duplicate_item(attr: TokenStream, item: TokenStream) -> TokenStream
 {
 	match duplicate_impl(attr, item)
 	{
 		Ok(result) => result,
-		Err(err) => abort(err),
+		Err(err) => emit_error(err),
 	}
 }
 
@@ -1049,13 +1046,12 @@ pub fn duplicate_item(attr: TokenStream, item: TokenStream) -> TokenStream
 /// The global substitutions (`typ1` and `typ2`) are substituted in both
 /// their occurrences. Global substitutions are `;` separated.
 #[proc_macro_attribute]
-#[cfg_attr(feature = "pretty_errors", proc_macro_error)]
 pub fn substitute_item(attr: TokenStream, item: TokenStream) -> TokenStream
 {
 	match substitute_impl(attr, item)
 	{
 		Ok(result) => result,
-		Err(err) => abort(err),
+		Err(err) => emit_error(err),
 	}
 }
 
@@ -1134,7 +1130,6 @@ pub fn substitute_item(attr: TokenStream, item: TokenStream) -> TokenStream
 ///
 /// [`duplicate_item`]: attr.duplicate_item.html
 #[proc_macro]
-#[cfg_attr(feature = "pretty_errors", proc_macro_error)]
 pub fn duplicate(stream: TokenStream) -> TokenStream
 {
 	inline_macro_impl(stream, duplicate_impl)
@@ -1180,7 +1175,6 @@ pub fn duplicate(stream: TokenStream) -> TokenStream
 /// The global substitutions (`typ1` and `typ2`) are substituted in both
 /// their occurrences. Global substitutions are `;` separated.
 #[proc_macro]
-#[cfg_attr(feature = "pretty_errors", proc_macro_error)]
 pub fn substitute(stream: TokenStream) -> TokenStream
 {
 	inline_macro_impl(stream, substitute_impl)
@@ -1217,7 +1211,7 @@ fn inline_macro_impl(
 	match result
 	{
 		Ok(result) => result,
-		Err(err) => abort(err),
+		Err(err) => emit_error(err),
 	}
 }
 
@@ -1243,17 +1237,15 @@ fn substitute_impl(attr: TokenStream, item: TokenStream) -> Result<TokenStream>
 ///
 /// The `pretty_errors` feature can be enabled, the span is shown
 /// with the error message.
-#[allow(unused_variables)]
-fn abort(err: Error) -> !
+fn emit_error(err: Error) -> TokenStream
 {
-	let (span, msg) = err.extract();
 	#[cfg(feature = "pretty_errors")]
 	{
-		abort!(span, msg);
+		err.into_diagnostic().emit_as_item_tokens().into()
 	}
 	#[cfg(not(feature = "pretty_errors"))]
 	{
-		panic!("{}", msg);
+		panic!("{}", err.into_panic_message());
 	}
 }
 

src/parse.rs

@@ -50,8 +50,7 @@ pub(crate) fn parse_global_substitutions_only(attr: TokenStream) -> Result<Subst
 					.unwrap_or(false)
 			{
 				err = err.hint(
-					"Hint: Only global substitutions are allowed. Try 'duplicate' or \
-					 'duplicate_item'.",
+					"Only global substitutions are allowed. Try 'duplicate' or 'duplicate_item'.",
 				);
 			}
 		}
@@ -171,7 +170,7 @@ fn validate_verbose_invocation<'a, T: SubGroupIter<'a>>(
 		{
 			let (body, span) = iter.next_group(Some(Delimiter::Bracket)).map_err(|err| {
 				err.hint(
-					"Hint: When using verbose syntax, a substitutions must be enclosed in a \
+					"When using verbose syntax, a substitutions must be enclosed in a \
 					 group.\nExample:\n..\n[\n\tidentifier1 [ substitution1 ]\n\tidentifier2 [ \
 					 substitution2 ]\n]",
 				)
@@ -228,7 +227,7 @@ fn extract_inline_substitution<'a, T: SubGroupIter<'a>>(
 		// No parameters, get substitution
 		substitution
 			.map(|(sub, _)| Substitution::new_simple(sub.process_all()))
-			.map_err(|old_err| Error::new("Expected '(' or '['.").span(old_err.extract().0))
+			.map_err(|old_err| Error::new("Expected '(' or '['.").span(old_err.get_span()))
 	}
 	.or_else(|err| {
 		stream.push_front(Token::Simple(TokenTree::Ident(ident.clone())));

src/pretty_errors.rs

@@ -1,7 +1,7 @@
 #![cfg_attr(not(feature = "pretty_errors"), allow(dead_code))]
 
 /// For when substitution parameters aren't enclosed in brackets
-pub(crate) const BRACKET_SUB_PARAM: &'static str = r#"Hint: Substitution parameters should be enclosed in '[]' each.
+pub(crate) const BRACKET_SUB_PARAM: &'static str = r#"Substitution parameters should be enclosed in '[]' each.
 Example:
     sub_ident( [ parameter1 ] , [ paramter2 ] )
               ^^^          ^^^ ^^^         ^^^
@@ -16,21 +16,20 @@ pub(crate) const NO_INVOCATION: &'static str =
 pub(crate) const NO_GROUPS: &'static str = r#"Expected substitution group."#;
 
 /// Hint for when no substitution group is given, but at least one must be given
-pub(crate) const NO_GROUPS_HINT: &'static str = "Hint: Must specify at least one substitution \
-                                                 group, otherwise use 'substitute!' or \
-                                                 'substitute_item'";
+pub(crate) const NO_GROUPS_HINT: &'static str = "Must specify at least one substitution group, \
+                                                 otherwise use 'substitute!' or 'substitute_item'";
 
 /// For when short syntax has declared substitution identifiers but no
 /// substitution groups.
-pub(crate) const SHORT_SYNTAX_NO_GROUPS: &'static str = r#"Hint: Add a substitution group after the substitution identifiers.
+pub(crate) const SHORT_SYNTAX_NO_GROUPS: &'static str = r#"Add a substitution group after the substitution identifiers.
 Example:
 	name;
 	[SomeSubstitution];
 	^^^^^^^^^^^^^^^^^^^
 "#;
 
 /// For when short syntax substitutions aren't enclosed in brackets
-pub(crate) const SHORT_SYNTAX_MISSING_SUB_BRACKET: &'static str = r#"Hint: Each substitution should be enclosed in '[]'.
+pub(crate) const SHORT_SYNTAX_MISSING_SUB_BRACKET: &'static str = r#"Each substitution should be enclosed in '[]'.
 Example:
     ident1 ident2;
     [ sub1 ] [ sub2 ] ;
@@ -39,7 +38,7 @@ Example:
 
 /// For when short syntax substitution group has too few or too many
 /// substitutions
-pub(crate) const SHORT_SYNTAX_SUBSTITUTION_COUNT: &'static str = r#"Hint: Number of substitutions must match the number of substitutions identifiers.
+pub(crate) const SHORT_SYNTAX_SUBSTITUTION_COUNT: &'static str = r#"Number of substitutions must match the number of substitutions identifiers.
 Example:
     ident1 ident2;
    1^^^^^^ ^^^^^^2
@@ -49,7 +48,7 @@ Example:
 
 /// For when verbose syntax substitution group has too few or too many
 /// substitutions
-pub(crate) const VERBOSE_SYNTAX_SUBSTITUTION_IDENTIFIERS: &'static str = r#"Hint: All substitution groups must define the same substitution identifiers.
+pub(crate) const VERBOSE_SYNTAX_SUBSTITUTION_IDENTIFIERS: &'static str = r#"All substitution groups must define the same substitution identifiers.
 Example:
     [
         ident1  [sub1]
@@ -63,7 +62,7 @@ Example:
 
 /// For when verbose syntax substitution identifier has too few or too many
 /// arguments
-pub(crate) const VERBOSE_SYNTAX_SUBSTITUTION_IDENTIFIERS_ARGS: &'static str = r#"Hint: The same substitution identifier must take the same number of argument across all substitution groups.
+pub(crate) const VERBOSE_SYNTAX_SUBSTITUTION_IDENTIFIERS_ARGS: &'static str = r#"The same substitution identifier must take the same number of argument across all substitution groups.
 Example:
     [
         ident1(arg1, arg2)  [sub1 arg1 arg2]
@@ -76,7 +75,7 @@ Example:
 "#;
 
 /// For when verbose syntax substitution pair is followed by a semicolon
-pub(crate) const VERBOSE_SEMICOLON: &'static str = r#"Hint: Verbose syntax does not accept semicolons between substitutions.
+pub(crate) const VERBOSE_SEMICOLON: &'static str = r#"Verbose syntax does not accept semicolons between substitutions.
 Example:
     [
         name    [sub1] // No semicolon
@@ -85,7 +84,7 @@ Example:
 "#;
 
 /// For when global substitutions aren't followed by ';'
-pub(crate) const GLOBAL_SUB_SEMICOLON: &'static str = r#"Hint: Each global substitution should end with ';'
+pub(crate) const GLOBAL_SUB_SEMICOLON: &'static str = r#"Each global substitution should end with ';'
 Example:
     name   [sub1];
     typ    [sub2];

src/token_iter.rs

@@ -264,7 +264,7 @@ impl<'a, T: SubGroupIter<'a>> TokenIter<'a, T>
 			let mut err = Error::new(error);
 			if let Some(expected_string) = expected
 			{
-				err = err.hint("Hint: Expected ".to_string() + expected_string + ".");
+				err = err.hint("Expected ".to_string() + expected_string + ".");
 			}
 			err
 		};

tests/errors/hint/duplicate_without_duplicates

@@ -1 +1 @@
-       Hint: Must specify at least one substitution group, otherwise use 'substitute!' or 'substitute_item'
+       = help: Must specify at least one substitution group, otherwise use 'substitute!' or 'substitute_item'

tests/errors/hint/global_sub_semicolon

@@ -1,4 +1,4 @@
-       Hint: Each global substitution should end with ';'
+       = help: Each global substitution should end with ';'
        Example:
            name   [sub1];
            typ    [sub2];

tests/errors/hint/parameters_not_encapsulated

@@ -1,4 +1,4 @@
-       Hint: Substitution parameters should be enclosed in '[]' each.
+       = help: Substitution parameters should be enclosed in '[]' each.
        Example:
            sub_ident( [ parameter1 ] , [ paramter2 ] )
                      ^^^          ^^^ ^^^         ^^^

tests/errors/hint/short_missing_substitution

@@ -1,4 +1,4 @@
-       Hint: Number of substitutions must match the number of substitutions identifiers.
+       = help: Number of substitutions must match the number of substitutions identifiers.
        Example:
            ident1 ident2;
           1^^^^^^ ^^^^^^2

tests/errors/hint/short_missing_substitution_bracket

@@ -1,4 +1,4 @@
-       Hint: Each substitution should be enclosed in '[]'.
+       = help: Each substitution should be enclosed in '[]'.
        Example:
            ident1 ident2;
            [ sub1 ] [ sub2 ] ;

tests/errors/hint/short_superfluous_substitution

@@ -1,4 +1,4 @@
-       Hint: Number of substitutions must match the number of substitutions identifiers.
+       = help: Number of substitutions must match the number of substitutions identifiers.
        Example:
            ident1 ident2;
           1^^^^^^ ^^^^^^2

tests/errors/hint/short_without_duplicates

@@ -1,4 +1,4 @@
-       Hint: Add a substitution group after the substitution identifiers.
+       = help: Add a substitution group after the substitution identifiers.
        Example:
            name;
            [SomeSubstitution];

tests/errors/hint/substitute_item_with_duplicate

@@ -1 +1 @@
-       Hint: Expected a substitution identifier.
+       = help: Expected a substitution identifier.

tests/errors/hint/substitute_item_with_duplicate_2

@@ -1 +1 @@
-       Hint: Only global substitutions are allowed. Try 'duplicate' or 'duplicate_item'.
+       = help: Only global substitutions are allowed. Try 'duplicate' or 'duplicate_item'.

tests/errors/hint/substitute_item_with_duplicate_3

@@ -1 +1 @@
-       Hint: Only global substitutions are allowed. Try 'duplicate' or 'duplicate_item'.
+       = help: Only global substitutions are allowed. Try 'duplicate' or 'duplicate_item'.

tests/errors/hint/substitute_item_with_duplicate_4

@@ -1 +1 @@
-       Hint: Expected a substitution identifier.
+       = help: Expected a substitution identifier.

tests/errors/hint/verbose_incomplete_substitution_group

@@ -1,5 +1,5 @@
-       Missing substitution for: 'ty'
-       Hint: All substitution groups must define the same substitution identifiers.
+       = help: Missing substitution for: 'ty'
+       All substitution groups must define the same substitution identifiers.
        Example:
            [
                ident1  [sub1]

tests/errors/hint/verbose_not_ident

@@ -1 +1 @@
-Hint: Expected a substitution identifier.
+= help: Expected a substitution identifier.

tests/errors/hint/verbose_semicolon

@@ -1,4 +1,4 @@
-       Hint: Verbose syntax does not accept semicolons between substitutions.
+       = help: Verbose syntax does not accept semicolons between substitutions.
        Example:
            [
                name    [sub1] // No semicolon

tests/errors/hint/verbose_unexpected_substitution_identifier

@@ -1,4 +1,4 @@
-       Hint: All substitution groups must define the same substitution identifiers.
+       = help: All substitution groups must define the same substitution identifiers.
        Example:
            [
                ident1  [sub1]

tests/errors/hint/verbose_wrong_argument_count

@@ -1,4 +1,4 @@
-       Hint: The same substitution identifier must take the same number of argument across all substitution groups.
+       = help: The same substitution identifier must take the same number of argument across all substitution groups.
        Example:
            [
                ident1(arg1, arg2)  [sub1 arg1 arg2]