remove redundant import (clippy::single_component_path_imports)

remove redundant format!() call (clippy::useless_format)
don't use ok() before calling expect() (clippy::ok_expect)

src/librustc_lint/types.rs

@@ -273,7 +273,6 @@ fn lint_int_literal<'a, 'tcx>(
                     cx.sess()
                         .source_map()
                         .span_to_snippet(lit.span)
-                        .ok()
                         .expect("must get snippet from literal"),
                     t.name_str(),
                     min,
@@ -338,7 +337,6 @@ fn lint_uint_literal<'a, 'tcx>(
                     cx.sess()
                         .source_map()
                         .span_to_snippet(lit.span)
-                        .ok()
                         .expect("must get snippet from literal"),
                     t.name_str(),
                     min,

src/librustc_typeck/impl_wf_check/min_specialization.rs

@@ -270,7 +270,7 @@ fn check_static_lifetimes<'tcx>(
     span: Span,
 ) {
     if tcx.any_free_region_meets(parent_substs, |r| *r == ty::ReStatic) {
-        tcx.sess.struct_span_err(span, &format!("cannot specialize on `'static` lifetime")).emit();
+        tcx.sess.struct_span_err(span, "cannot specialize on `'static` lifetime").emit();
     }
 }
 

src/librustdoc/passes/calculate_doc_coverage.rs

@@ -8,7 +8,6 @@ use rustc_ast::attr;
 use rustc_span::symbol::sym;
 use rustc_span::FileName;
 use serde::Serialize;
-use serde_json;
 
 use std::collections::BTreeMap;
 use std::ops;