templater: unify variants of type error as general expression error

I'm going to add a lambda expression, and the current type-error message
wouldn't work for the lambda type. I also renamed "argument" to "expression"
as the expect_<type>() helper may be called against any expression node.

src/template_builder.rs

@@ -17,7 +17,7 @@ use jujutsu_lib::backend::{Signature, Timestamp};
 
 use crate::template_parser::{
     self, ExpressionKind, ExpressionNode, FunctionCallNode, MethodCallNode, TemplateParseError,
-    TemplateParseErrorKind, TemplateParseResult,
+    TemplateParseResult,
 };
 use crate::templater::{
     ConcatTemplate, ConditionalTemplate, FormattablePropertyListTemplate, IntoTemplate,
@@ -388,8 +388,7 @@ fn build_timestamp_method<'a, L: TemplateLanguage<'a>>(
             let format =
                 template_parser::expect_string_literal_with(format_node, |format, span| {
                     time_util::FormattingItems::parse(format).ok_or_else(|| {
-                        let kind = TemplateParseErrorKind::InvalidTimeFormat;
-                        TemplateParseError::with_span(kind, span)
+                        TemplateParseError::unexpected_expression("Invalid time format", span)
                     })
                 })?
                 .into_owned();
@@ -570,7 +569,7 @@ pub fn expect_boolean_expression<'a, L: TemplateLanguage<'a>>(
 ) -> TemplateParseResult<Box<dyn TemplateProperty<L::Context, Output = bool> + 'a>> {
     build_expression(language, node)?
         .try_into_boolean()
-        .ok_or_else(|| TemplateParseError::invalid_argument_type("Boolean", node.span))
+        .ok_or_else(|| TemplateParseError::expected_type("Boolean", node.span))
 }
 
 pub fn expect_integer_expression<'a, L: TemplateLanguage<'a>>(
@@ -579,5 +578,5 @@ pub fn expect_integer_expression<'a, L: TemplateLanguage<'a>>(
 ) -> TemplateParseResult<Box<dyn TemplateProperty<L::Context, Output = i64> + 'a>> {
     build_expression(language, node)?
         .try_into_integer()
-        .ok_or_else(|| TemplateParseError::invalid_argument_type("Integer", node.span))
+        .ok_or_else(|| TemplateParseError::expected_type("Integer", node.span))
 }

src/template_parser.rs

@@ -49,12 +49,10 @@ pub enum TemplateParseErrorKind {
     NoSuchMethod { type_name: String, name: String },
     #[error(r#"Function "{name}": {message}"#)]
     InvalidArguments { name: String, message: String },
-    #[error(r#"Expected argument of type "{0}""#)]
-    InvalidArgumentType(String),
-    #[error("Invalid time format")]
-    InvalidTimeFormat,
     #[error("Redefinition of function parameter")]
     RedefinedFunctionParameter,
+    #[error("{0}")]
+    UnexpectedExpression(String),
     #[error(r#"Alias "{0}" cannot be expanded"#)]
     BadAliasExpansion(String),
     #[error(r#"Alias "{0}" expanded recursively"#)]
@@ -125,12 +123,14 @@ impl TemplateParseError {
         )
     }
 
-    pub fn invalid_argument_type(
-        expected_type_name: impl Into<String>,
-        span: pest::Span<'_>,
-    ) -> Self {
+    pub fn expected_type(type_name: &str, span: pest::Span<'_>) -> Self {
+        let message = format!(r#"Expected expression of type "{type_name}""#);
+        TemplateParseError::unexpected_expression(message, span)
+    }
+
+    pub fn unexpected_expression(message: impl Into<String>, span: pest::Span<'_>) -> Self {
         TemplateParseError::with_span(
-            TemplateParseErrorKind::InvalidArgumentType(expected_type_name.into()),
+            TemplateParseErrorKind::UnexpectedExpression(message.into()),
             span,
         )
     }
@@ -636,8 +636,8 @@ pub fn expect_string_literal_with<'a, 'i, T>(
         | ExpressionKind::Integer(_)
         | ExpressionKind::Concat(_)
         | ExpressionKind::FunctionCall(_)
-        | ExpressionKind::MethodCall(_) => Err(TemplateParseError::invalid_argument_type(
-            "String literal",
+        | ExpressionKind::MethodCall(_) => Err(TemplateParseError::unexpected_expression(
+            "Expected string literal",
             node.span,
         )),
         ExpressionKind::AliasExpanded(id, subst) => expect_string_literal_with(subst, f)

tests/test_templater.rs

@@ -232,7 +232,7 @@ fn test_templater_parse_error() {
     1 | if(label("foo", "bar"), "baz")
       |    ^-----------------^
       |
-      = Expected argument of type "Boolean"
+      = Expected expression of type "Boolean"
     "###);
 }
 
@@ -368,7 +368,7 @@ fn test_templater_timestamp_method() {
     1 | author.timestamp().format(0)
       |                           ^
       |
-      = Expected argument of type "String literal"
+      = Expected string literal
     "###);
 
     // Dynamic string isn't supported yet
@@ -378,7 +378,7 @@ fn test_templater_timestamp_method() {
     1 | author.timestamp().format("%Y" ++ "%m")
       |                           ^----------^
       |
-      = Expected argument of type "String literal"
+      = Expected string literal
     "###);
 
     // Literal alias expansion
@@ -657,7 +657,7 @@ fn test_templater_alias() {
     1 | identity(identity(commit_id.short("")))
       |                                   ^^
       |
-      = Expected argument of type "Integer"
+      = Expected expression of type "Integer"
     "###);
 
     insta::assert_snapshot!(render_err("commit_id ++ recurse"), @r###"
@@ -716,7 +716,7 @@ fn test_templater_alias() {
     1 | coalesce(label("x", "not boolean"), "")
       |          ^-----------------------^
       |
-      = Expected argument of type "Boolean"
+      = Expected expression of type "Boolean"
     "###);
 }