Implement new eBNF for codeblock attributes

tests/rustdoc-ui/custom_code_classes_in_docs-warning.rs

@@ -6,14 +6,80 @@
 #![feature(no_core)]
 #![no_core]
 
-/// ```{. class= whatever=hehe #id} } {{
+/// ```{. }
 /// main;
 /// ```
-//~^^^ ERROR missing class name after `.`
-//~| ERROR missing class name after `class=`
-//~| ERROR unsupported attribute `whatever=hehe`
-//~| ERROR unsupported attribute `#id`
-//~| ERROR unexpected `}` outside attribute block (`{}`)
-//~| ERROR unclosed attribute block (`{}`): missing `}` at the end
-//~| ERROR unexpected `{` inside attribute block (`{}`)
+//~^^^ ERROR unexpected ` ` character after `.`
 pub fn foo() {}
+
+/// ```{class= a}
+/// main;
+/// ```
+//~^^^ ERROR unexpected ` ` character after `=`
+pub fn foo2() {}
+
+/// ```{#id}
+/// main;
+/// ```
+//~^^^ ERROR unexpected character `#`
+pub fn foo3() {}
+
+/// ```{{
+/// main;
+/// ```
+//~^^^ ERROR unexpected character `{`
+pub fn foo4() {}
+
+/// ```}
+/// main;
+/// ```
+//~^^^ ERROR unexpected character `}`
+pub fn foo5() {}
+
+/// ```)
+/// main;
+/// ```
+//~^^^ ERROR unexpected character `)`
+pub fn foo6() {}
+
+/// ```{class=}
+/// main;
+/// ```
+//~^^^ ERROR unexpected `}` character after `=`
+pub fn foo7() {}
+
+/// ```(
+/// main;
+/// ```
+//~^^^ ERROR unclosed comment: missing `)` at the end
+pub fn foo8() {}
+
+/// ```{class=one=two}
+/// main;
+/// ```
+//~^^^ ERROR unexpected `=`
+pub fn foo9() {}
+
+/// ```{.one.two}
+/// main;
+/// ```
+//~^^^ ERROR unexpected `.` character
+pub fn foo10() {}
+
+/// ```{class=.one}
+/// main;
+/// ```
+//~^^^ ERROR unexpected `.` character after `=`
+pub fn foo11() {}
+
+/// ```{class=one.two}
+/// main;
+/// ```
+//~^^^ ERROR unexpected `.` character
+pub fn foo12() {}
+
+/// ```{(comment)}
+/// main;
+/// ```
+//~^^^ ERROR unexpected character `(`
+pub fn foo13() {}