Trim leading asterisks from doc block comments

This is to handle a change in behaviour in current beta rustc

schemars_derive/src/attr/doc.rs

@@ -32,7 +32,7 @@ fn merge_description_lines(doc: &str) -> Option<String> {
 }
 
 fn get_doc(attrs: &[Attribute]) -> Option<String> {
-    let doc = attrs
+    let attrs = attrs
         .iter()
         .filter_map(|attr| {
             if !attr.path.is_ident("doc") {
@@ -46,14 +46,31 @@ fn get_doc(attrs: &[Attribute]) -> Option<String> {
 
             None
         })
-        .collect::<Vec<_>>()
+        .collect::<Vec<_>>();
+
+    let mut lines = attrs
         .iter()
         .flat_map(|a| a.split('\n'))
         .map(str::trim)
         .skip_while(|s| *s == "")
-        .collect::<Vec<_>>()
-        .join("\n");
-    none_if_empty(doc)
+        .collect::<Vec<_>>();
+
+    if let Some(&"") = lines.last() {
+        lines.pop();
+    }
+
+    // Added for backward-compatibility, but perhaps we shouldn't do this
+    // https://github.com/rust-lang/rust/issues/32088
+    if lines.iter().all(|l| l.starts_with("*")) {
+        for line in lines.iter_mut() {
+            *line = line[1..].trim()
+        }
+        while let Some(&"") = lines.first() {
+            lines.remove(0);
+        }
+    };
+
+    none_if_empty(lines.join("\n"))
 }
 
 fn none_if_empty(s: String) -> Option<String> {