diff --git a/src/librustc/hir/map/definitions.rs b/src/librustc/hir/map/definitions.rs
index cc099fcc40f6d..d2732c92d2688 100644
--- a/src/librustc/hir/map/definitions.rs
+++ b/src/librustc/hir/map/definitions.rs
@@ -111,7 +111,7 @@ pub struct Definitions {
 /// A unique identifier that we can use to lookup a definition
 /// precisely. It combines the index of the definition's parent (if
 /// any) with a `DisambiguatedDefPathData`.
-#[derive(Clone, PartialEq, Debug, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub struct DefKey {
     /// The parent path.
     pub parent: Option<DefIndex>,
@@ -162,13 +162,13 @@ impl DefKey {
 /// between them. This introduces some artificial ordering dependency
 /// but means that if you have, e.g., two impls for the same type in
 /// the same module, they do get distinct `DefId`s.
-#[derive(Clone, PartialEq, Debug, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub struct DisambiguatedDefPathData {
     pub data: DefPathData,
     pub disambiguator: u32
 }
 
-#[derive(Clone, Debug, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 pub struct DefPath {
     /// The path leading from the crate root to the item.
     pub data: Vec<DisambiguatedDefPathData>,
diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs
index 8845b66a7cefd..fa9567fb62c0f 100644
--- a/src/libsyntax_pos/symbol.rs
+++ b/src/libsyntax_pos/symbol.rs
@@ -934,19 +934,19 @@ impl Symbol {
 
 impl fmt::Debug for Symbol {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(self, f)
+        self.with(|str| fmt::Debug::fmt(&str, f))
     }
 }
 
 impl fmt::Display for Symbol {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&self.as_str(), f)
+        self.with(|str| fmt::Display::fmt(&str, f))
     }
 }
 
 impl Encodable for Symbol {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_str(&self.as_str())
+        self.with(|string| s.emit_str(string))
     }
 }
 
@@ -1106,8 +1106,8 @@ fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
 }
 
 /// An alternative to `Symbol` and `InternedString`, useful when the chars
-/// within the symbol need to be accessed. It is best used for temporary
-/// values.
+/// within the symbol need to be accessed. It deliberately has limited
+/// functionality and should only be used for temporary values.
 ///
 /// Because the interner outlives any thread which uses this type, we can
 /// safely treat `string` which points to interner data, as an immortal string,
@@ -1116,7 +1116,7 @@ fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
 // FIXME: ensure that the interner outlives any thread which uses
 // `LocalInternedString`, by creating a new thread right after constructing the
 // interner.
-#[derive(Clone, Copy, Eq, PartialOrd, Ord)]
+#[derive(Eq, PartialOrd, Ord)]
 pub struct LocalInternedString {
     string: &'static str,
 }
diff --git a/src/test/ui/hygiene/unpretty-debug.stdout b/src/test/ui/hygiene/unpretty-debug.stdout
index 6971873ba601e..acd852103cae3 100644
--- a/src/test/ui/hygiene/unpretty-debug.stdout
+++ b/src/test/ui/hygiene/unpretty-debug.stdout
@@ -17,7 +17,7 @@ fn y /* 0#0 */() { }
 /*
 Expansions:
 0: parent: ExpnId(0), call_site_ctxt: #0, kind: Root
-1: parent: ExpnId(0), call_site_ctxt: #0, kind: Macro(Bang, foo)
+1: parent: ExpnId(0), call_site_ctxt: #0, kind: Macro(Bang, "foo")
 
 SyntaxContexts:
 #0: parent: #0, outer_mark: (ExpnId(0), Opaque)
diff --git a/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr b/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
index 5f289c0914d6e..2160df51a8375 100644
--- a/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
+++ b/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
@@ -1,4 +1,4 @@
-TokenStream [Ident { ident: "fn", span: #0 bytes(197..199) }, Ident { ident: "span_preservation", span: #0 bytes(200..217) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(217..219) }, Group { delimiter: Brace, stream: TokenStream [Ident { ident: "let", span: #0 bytes(227..230) }, Ident { ident: "tst", span: #0 bytes(231..234) }, Punct { ch: '=', spacing: Alone, span: #0 bytes(235..236) }, Literal { lit: Lit { kind: Integer, symbol: 123, suffix: None }, span: Span { lo: BytePos(237), hi: BytePos(240), ctxt: #0 } }, Punct { ch: ';', spacing: Joint, span: #0 bytes(240..241) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(241..242) }, Ident { ident: "match", span: #0 bytes(288..293) }, Ident { ident: "tst", span: #0 bytes(294..297) }, Group { delimiter: Brace, stream: TokenStream [Literal { lit: Lit { kind: Integer, symbol: 123, suffix: None }, span: Span { lo: BytePos(482), hi: BytePos(485), ctxt: #0 } }, Punct { ch: '=', spacing: Joint, span: #0 bytes(486..488) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(486..488) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(489..491) }, Punct { ch: ',', spacing: Alone, span: #0 bytes(491..492) }, Ident { ident: "_", span: #0 bytes(501..502) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(503..505) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(503..505) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(506..508) }], span: #0 bytes(298..514) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(514..515) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(515..516) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(516..517) }], span: #0 bytes(221..561) }]
+TokenStream [Ident { ident: "fn", span: #0 bytes(197..199) }, Ident { ident: "span_preservation", span: #0 bytes(200..217) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(217..219) }, Group { delimiter: Brace, stream: TokenStream [Ident { ident: "let", span: #0 bytes(227..230) }, Ident { ident: "tst", span: #0 bytes(231..234) }, Punct { ch: '=', spacing: Alone, span: #0 bytes(235..236) }, Literal { lit: Lit { kind: Integer, symbol: "123", suffix: None }, span: Span { lo: BytePos(237), hi: BytePos(240), ctxt: #0 } }, Punct { ch: ';', spacing: Joint, span: #0 bytes(240..241) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(241..242) }, Ident { ident: "match", span: #0 bytes(288..293) }, Ident { ident: "tst", span: #0 bytes(294..297) }, Group { delimiter: Brace, stream: TokenStream [Literal { lit: Lit { kind: Integer, symbol: "123", suffix: None }, span: Span { lo: BytePos(482), hi: BytePos(485), ctxt: #0 } }, Punct { ch: '=', spacing: Joint, span: #0 bytes(486..488) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(486..488) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(489..491) }, Punct { ch: ',', spacing: Alone, span: #0 bytes(491..492) }, Ident { ident: "_", span: #0 bytes(501..502) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(503..505) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(503..505) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(506..508) }], span: #0 bytes(298..514) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(514..515) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(515..516) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(516..517) }], span: #0 bytes(221..561) }]
 error: unnecessary trailing semicolon
   --> $DIR/redundant-semi-proc-macro.rs:9:19
    |