Improve config delimiters characters check

rinja_parser/src/lib.rs

@@ -806,13 +806,13 @@ impl<'a> SyntaxBuilder<'a> {
             comment_end: self.comment_end.unwrap_or(default.comment_end),
         });
 
-        for (s, k) in [
-            (syntax.block_start, "opening block"),
-            (syntax.block_end, "closing block"),
-            (syntax.expr_start, "opening expression"),
-            (syntax.expr_end, "closing expression"),
-            (syntax.comment_start, "opening comment"),
-            (syntax.comment_end, "closing comment"),
+        for (s, k, is_closing) in [
+            (syntax.block_start, "opening block", false),
+            (syntax.block_end, "closing block", true),
+            (syntax.expr_start, "opening expression", false),
+            (syntax.expr_end, "closing expression", true),
+            (syntax.comment_start, "opening comment", false),
+            (syntax.comment_end, "closing comment", true),
         ] {
             if s.len() < 2 {
                 return Err(format!(
@@ -824,6 +824,15 @@ impl<'a> SyntaxBuilder<'a> {
                     "delimiters may not contain white spaces. \
                         The {k} delimiter ({s:?}) contains white spaces",
                 ));
+            } else if is_closing
+                && ['(', '-', '+', '~', '.', '>', '<', '&', '|', '!']
+                    .contains(&s.chars().next().unwrap())
+            {
+                return Err(format!(
+                    "closing delimiters may not start with operators. \
+                        The {k} delimiter ({s:?}) starts with operator `{}`",
+                    s.chars().next().unwrap(),
+                ));
             }
         }
 
@@ -853,29 +862,6 @@ impl<'a> SyntaxBuilder<'a> {
             }
         }
 
-        for (end, kind) in [
-            (syntax.block_end, "block"),
-            (syntax.expr_end, "expression"),
-            (syntax.comment_end, "comment"),
-        ] {
-            for prefix in ["<<", ">>", "&&", "..", "||"] {
-                if end.starts_with(prefix) {
-                    let msg = if end == prefix {
-                        format!(
-                            "a closing delimiter must not start with an operator. \
-                             The {kind} delimiter ({end:?}) is also an operator",
-                        )
-                    } else {
-                        format!(
-                            "a closing delimiter must not start an with operator. \
-                             The {kind} delimiter ({end:?}) starts with the {prefix:?} operator",
-                        )
-                    };
-                    return Err(msg);
-                }
-            }
-        }
-
         Ok(syntax)
     }
 }

testing/operator-paren-config.toml

@@ -0,0 +1,4 @@
+[[syntax]]
+name = "paren"
+expr_start = "<)"
+expr_end = "(>"

testing/operator-plus-config.toml

@@ -0,0 +1,4 @@
+[[syntax]]
+name = "plus"
+expr_start = "<+"
+expr_end = "+>"

testing/tests/ui/broken-config.rs

@@ -16,4 +16,12 @@ struct DelimClash;
 #[template(source = "", ext = "txt", config = "delim-too-short.toml")]
 struct DelimTooShort;
 
+#[derive(Template)]
+#[template(source = "<+a+> and <+b+>", config = "operator-plus-config.toml", syntax = "plus", ext = "txt")]
+struct PlusOperator;
+
+#[derive(Template)]
+#[template(source = "<)a(> and <)b(>", config = "operator-paren-config.toml", syntax = "paren", ext = "txt")]
+struct ParenOperator;
+
 fn main() {}

testing/tests/ui/broken-config.stderr

@@ -23,3 +23,17 @@ error: delimiters must be at least two characters long. The opening block delimi
    |
 16 | #[template(source = "", ext = "txt", config = "delim-too-short.toml")]
    |                                               ^^^^^^^^^^^^^^^^^^^^^^
+
+error: closing delimiters may not start with operators. The closing expression delimiter ("+>") starts with operator `+`
+        --> testing/operator-plus-config.toml
+  --> tests/ui/broken-config.rs:20:49
+   |
+20 | #[template(source = "<+a+> and <+b+>", config = "operator-plus-config.toml", syntax = "plus", ext = "txt")]
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: closing delimiters may not start with operators. The closing expression delimiter ("(>") starts with operator `(`
+        --> testing/operator-paren-config.toml
+  --> tests/ui/broken-config.rs:24:49
+   |
+24 | #[template(source = "<)a(> and <)b(>", config = "operator-paren-config.toml", syntax = "paren", ext = "txt")]
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

testing/tests/ui/terminator-operator.stderr

@@ -1,11 +1,11 @@
-error: a closing delimiter must not start with an operator. The expression delimiter (">>") is also an operator
+error: closing delimiters may not start with operators. The closing expression delimiter (">>") starts with operator `>`
         --> testing/issue-128.toml
  --> tests/ui/terminator-operator.rs:4:49
   |
 4 | #[template(source = "<<a>> and <<b>>", config = "issue-128.toml", syntax = "mwe", ext="")]
   |                                                 ^^^^^^^^^^^^^^^^
 
-error: a closing delimiter must not start an with operator. The expression delimiter (">>>") starts with the ">>" operator
+error: closing delimiters may not start with operators. The closing expression delimiter (">>>") starts with operator `>`
         --> testing/issue-128-2.toml
   --> tests/ui/terminator-operator.rs:11:49
    |