compiler: remove unnecessary imports and qualified paths

compiler/rustc_parse/src/parser/attr.rs

@@ -6,7 +6,6 @@ use rustc_ast::attr;
 use rustc_ast::token::{self, Delimiter, Nonterminal};
 use rustc_errors::{error_code, fluent, Diagnostic, IntoDiagnostic, PResult};
 use rustc_span::{sym, BytePos, Span};
-use std::convert::TryInto;
 
 // Public for rustfmt usage
 #[derive(Debug)]

compiler/rustc_parse/src/parser/attr_wrapper.rs

@@ -8,7 +8,6 @@ use rustc_errors::PResult;
 use rustc_session::parse::ParseSess;
 use rustc_span::{sym, Span, DUMMY_SP};
 
-use std::convert::TryInto;
 use std::ops::Range;
 
 /// A wrapper type to ensure that the parser handles outer attributes correctly.

compiler/rustc_parse/src/parser/item.rs

@@ -21,7 +21,6 @@ use rustc_span::lev_distance::lev_distance;
 use rustc_span::source_map::{self, Span};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::DUMMY_SP;
-use std::convert::TryFrom;
 use std::mem;
 use thin_vec::ThinVec;
 use tracing::debug;