Change the error message to make it start at the as keyword

rinja_parser/src/expr.rs

@@ -195,8 +195,8 @@ impl<'a> Expr<'a> {
 
     fn is_as(i: &'a str, level: Level) -> ParseResult<'a, WithSpan<'a, Self>> {
         let start = i;
-        let (i, lhs) = Self::filtered(i, level)?;
+        let (before_keyword, lhs) = Self::filtered(i, level)?;
-        let (j, rhs) = opt(ws(identifier))(i)?;
+        let (j, rhs) = opt(ws(identifier))(before_keyword)?;
         let i = match rhs {
             Some("is") => j,
             Some("as") => {
@@ -207,7 +207,7 @@ impl<'a> Expr<'a> {
                 } else if target.is_empty() {
                     return Err(nom::Err::Failure(ErrorContext::new(
                         "`as` operator expects the name of a primitive type on its right-hand side",
-                        start,
+                        before_keyword.trim_start(),
                     )));
                 } else {
                     return Err(nom::Err::Failure(ErrorContext::new(
@@ -215,11 +215,11 @@ impl<'a> Expr<'a> {
                             "`as` operator expects the name of a primitive type on its right-hand \
                               side, found `{target}`"
                         ),
-                        start,
+                        before_keyword.trim_start(),
                     )));
                 }
             }
-            _ => return Ok((i, lhs)),
+            _ => return Ok((before_keyword, lhs)),
         };
 
         let (i, rhs) = opt(terminated(opt(keyword("not")), ws(keyword("defined"))))(i)?;

testing/tests/ui/as-primitive-type.rs

@@ -20,5 +20,9 @@ struct D;
 #[template(source = r#"{{ 1234 as int32_t }}"#, ext = "html")]
 struct E;
 
+#[derive(Template)]
+#[template(source = r#"{{ (1234 + 4 * 12 / 45675445 - 13) as int32_t }}"#, ext = "html")]
+struct F;
+
 fn main() {
 }

testing/tests/ui/as-primitive-type.stderr

@@ -1,6 +1,6 @@
 error: `as` operator expects the name of a primitive type on its right-hand side
-       failed to parse template source at row 1, column 3 near:
+       failed to parse template source at row 1, column 8 near:
-       "1234 as 4567 }}"
+       "as 4567 }}"
  --> tests/ui/as-primitive-type.rs:3:10
   |
 3 | #[derive(Template)]
@@ -9,8 +9,8 @@ error: `as` operator expects the name of a primitive type on its right-hand side
   = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `as` operator expects the name of a primitive type on its right-hand side
-       failed to parse template source at row 1, column 3 near:
+       failed to parse template source at row 1, column 8 near:
-       "1234 as ? }}"
+       "as ? }}"
  --> tests/ui/as-primitive-type.rs:7:10
   |
 7 | #[derive(Template)]
@@ -19,8 +19,8 @@ error: `as` operator expects the name of a primitive type on its right-hand side
   = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `as` operator expects the name of a primitive type on its right-hand side, found `u1234`
-       failed to parse template source at row 1, column 3 near:
+       failed to parse template source at row 1, column 8 near:
-       "1234 as u1234 }}"
+       "as u1234 }}"
   --> tests/ui/as-primitive-type.rs:11:10
    |
 11 | #[derive(Template)]
@@ -29,8 +29,8 @@ error: `as` operator expects the name of a primitive type on its right-hand side
    = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `as` operator expects the name of a primitive type on its right-hand side, found `core`
-       failed to parse template source at row 1, column 3 near:
+       failed to parse template source at row 1, column 8 near:
-       "1234 as core::primitive::u32 }}"
+       "as core::primitive::u32 }}"
   --> tests/ui/as-primitive-type.rs:15:10
    |
 15 | #[derive(Template)]
@@ -39,11 +39,21 @@ error: `as` operator expects the name of a primitive type on its right-hand side
    = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `as` operator expects the name of a primitive type on its right-hand side, found `int32_t`
-       failed to parse template source at row 1, column 3 near:
+       failed to parse template source at row 1, column 8 near:
-       "1234 as int32_t }}"
+       "as int32_t }}"
   --> tests/ui/as-primitive-type.rs:19:10
    |
 19 | #[derive(Template)]
    |          ^^^^^^^^
    |
    = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: `as` operator expects the name of a primitive type on its right-hand side, found `int32_t`
+       failed to parse template source at row 1, column 35 near:
+       "as int32_t }}"
+  --> tests/ui/as-primitive-type.rs:23:10
+   |
+23 | #[derive(Template)]
+   |          ^^^^^^^^
+   |
+   = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)