fileset, templater: insert intermediate InvalidArguments error type

This will help extract common FunctionCallNode<'i, T> type. We don't need
freedom of arbitrary error type choices, but implementing From<_> is the
easiest option I can think of. Another option is to constrain error type by
the expression type T through "T::ParseError: ArgumentsParseError" or
something, but it seemed a bit weird that we have to use trait just for that.

cli/src/template_parser.rs

@@ -18,7 +18,7 @@ use std::{error, mem};
 use itertools::Itertools as _;
 use jj_lib::dsl_util::{
     collect_similar, AliasDeclaration, AliasDeclarationParser, AliasId, AliasesMap,
-    StringLiteralParser,
+    InvalidArguments, StringLiteralParser,
 };
 use once_cell::sync::Lazy;
 use pest::iterators::{Pair, Pairs};
@@ -149,16 +149,6 @@ impl TemplateParseError {
         )
     }
 
-    pub fn invalid_arguments(name: &str, message: String, span: pest::Span<'_>) -> Self {
-        TemplateParseError::with_span(
-            TemplateParseErrorKind::InvalidArguments {
-                name: name.to_owned(),
-                message,
-            },
-            span,
-        )
-    }
-
     pub fn expected_type(expected: &str, actual: &str, span: pest::Span<'_>) -> Self {
         let message =
             format!(r#"Expected expression of type "{expected}", but actual type is "{actual}""#);
@@ -238,6 +228,16 @@ impl From<pest::error::Error<Rule>> for TemplateParseError {
     }
 }
 
+impl From<InvalidArguments<'_>> for TemplateParseError {
+    fn from(err: InvalidArguments<'_>) -> Self {
+        let kind = TemplateParseErrorKind::InvalidArguments {
+            name: err.name.to_owned(),
+            message: err.message,
+        };
+        Self::with_span(kind, err.span)
+    }
+}
+
 fn rename_rules_in_pest_error(err: pest::error::Error<Rule>) -> pest::error::Error<Rule> {
     err.renamed_rules(|rule| {
         rule.to_symbol()
@@ -623,11 +623,12 @@ pub fn expand_aliases<'i>(
             ExpressionKind::FunctionCall(function) => {
                 if let Some((id, params, defn)) = state.aliases_map.get_function(function.name) {
                     if function.args.len() != params.len() {
-                        return Err(TemplateParseError::invalid_arguments(
+                        return Err(InvalidArguments {
-                            function.name,
+                            name: function.name,
-                            format!("Expected {} arguments", params.len()),
+                            message: format!("Expected {} arguments", params.len()),
-                            function.args_span,
+                            span: function.args_span,
-                        ));
+                        }
+                        .into());
                     }
                     // Resolve arguments in the current scope, and pass them in to the alias
                     // expansion scope.
@@ -727,7 +728,11 @@ impl<'i> FunctionCallNode<'i> {
     }
 
     fn invalid_arguments(&self, message: String) -> TemplateParseError {
-        TemplateParseError::invalid_arguments(self.name, message, self.args_span)
+        InvalidArguments {
+            name: self.name,
+            message,
+            span: self.args_span,
+        }.into()
     }
 }
 

lib/src/dsl_util.rs

@@ -21,6 +21,20 @@ use itertools::Itertools as _;
 use pest::iterators::Pairs;
 use pest::RuleType;
 
+/// Unexpected number of arguments, or invalid combination of arguments.
+///
+/// This error is supposed to be converted to language-specific parse error
+/// type, where lifetime `'i` will be eliminated.
+#[derive(Clone, Debug)]
+pub struct InvalidArguments<'i> {
+    /// Function name.
+    pub name: &'i str,
+    /// Error message.
+    pub message: String,
+    /// Span of the bad arguments.
+    pub span: pest::Span<'i>,
+}
+
 /// Helper to parse string literal.
 #[derive(Debug)]
 pub struct StringLiteralParser<R> {

lib/src/fileset_parser.rs

@@ -24,7 +24,7 @@ use pest::Parser;
 use pest_derive::Parser;
 use thiserror::Error;
 
-use crate::dsl_util::StringLiteralParser;
+use crate::dsl_util::{InvalidArguments, StringLiteralParser};
 
 #[derive(Parser)]
 #[grammar = "fileset.pest"]
@@ -121,17 +121,6 @@ impl FilesetParseError {
         self
     }
 
-    /// Unexpected number of arguments, or invalid combination of arguments.
-    pub(super) fn invalid_arguments(name: &str, message: String, span: pest::Span<'_>) -> Self {
-        FilesetParseError::new(
-            FilesetParseErrorKind::InvalidArguments {
-                name: name.to_owned(),
-                message,
-            },
-            span,
-        )
-    }
-
     /// Some other expression error.
     pub(super) fn expression(message: impl Into<String>, span: pest::Span<'_>) -> Self {
         FilesetParseError::new(FilesetParseErrorKind::Expression(message.into()), span)
@@ -153,6 +142,15 @@ impl From<pest::error::Error<Rule>> for FilesetParseError {
     }
 }
 
+impl From<InvalidArguments<'_>> for FilesetParseError {
+    fn from(err: InvalidArguments<'_>) -> Self {
+        let kind = FilesetParseErrorKind::InvalidArguments {
+            name: err.name.to_owned(),
+            message: err.message,
+        };
+        Self::new(kind, err.span)
+    }
+}
 fn rename_rules_in_pest_error(err: pest::error::Error<Rule>) -> pest::error::Error<Rule> {
     err.renamed_rules(|rule| {
         rule.to_symbol()
@@ -349,7 +347,12 @@ impl<'i> FunctionCallNode<'i> {
     }
 
     fn invalid_arguments(&self, message: String) -> FilesetParseError {
-        FilesetParseError::invalid_arguments(self.name, message, self.args_span)
+        InvalidArguments {
+            name: self.name,
+            message,
+            span: self.args_span,
+        }
+        .into()
     }
 }