Improve Debug representations
diff --git a/src/lib.rs b/src/lib.rs
index 7b9a919..21becec 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -251,7 +251,7 @@
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub enum TokenTree {
     Group(Group),
     Term(Term),
@@ -314,7 +314,20 @@
     }
 }
 
-#[derive(Clone, Debug)]
+impl fmt::Debug for TokenTree {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // Each of these has the name in the struct type in the derived debug,
+        // so don't bother with an extra layer of indirection
+        match *self {
+            TokenTree::Group(ref t) => t.fmt(f),
+            TokenTree::Term(ref t) => t.fmt(f),
+            TokenTree::Op(ref t) => t.fmt(f),
+            TokenTree::Literal(ref t) => t.fmt(f),
+        }
+    }
+}
+
+#[derive(Clone)]
 pub struct Group {
     delimiter: Delimiter,
     stream: TokenStream,
@@ -361,7 +374,18 @@
     }
 }
 
-#[derive(Copy, Clone, Debug)]
+impl fmt::Debug for Group {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Group");
+        debug.field("delimiter", &self.delimiter);
+        debug.field("stream", &self.stream);
+        #[cfg(procmacro2_semver_exempt)]
+        debug.field("span", &self.span);
+        debug.finish()
+    }
+}
+
+#[derive(Copy, Clone)]
 pub struct Op {
     op: char,
     spacing: Spacing,
@@ -406,6 +430,17 @@
     }
 }
 
+impl fmt::Debug for Op {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Op");
+        debug.field("op", &self.op);
+        debug.field("spacing", &self.spacing);
+        #[cfg(procmacro2_semver_exempt)]
+        debug.field("span", &self.span);
+        debug.finish()
+    }
+}
+
 #[derive(Copy, Clone)]
 pub struct Term {
     inner: imp::Term,
diff --git a/src/stable.rs b/src/stable.rs
index ad9870c..1ca48a5 100644
--- a/src/stable.rs
+++ b/src/stable.rs
@@ -16,7 +16,7 @@
 
 use {Delimiter, Group, Op, Spacing, TokenTree};
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub struct TokenStream {
     inner: Vec<TokenTree>,
 }
@@ -111,6 +111,13 @@
     }
 }
 
+impl fmt::Debug for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("TokenStream ")?;
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
 #[cfg(feature = "proc-macro")]
 impl From<::proc_macro::TokenStream> for TokenStream {
     fn from(inner: ::proc_macro::TokenStream) -> TokenStream {
@@ -314,7 +321,7 @@
     }
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, PartialEq, Eq)]
 pub struct Span {
     #[cfg(procmacro2_semver_exempt)]
     lo: u32,
@@ -393,6 +400,16 @@
     }
 }
 
+impl fmt::Debug for Span {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        #[cfg(procmacro2_semver_exempt)]
+        return write!(f, "bytes({}..{})", self.lo, self.hi);
+
+        #[cfg(not(procmacro2_semver_exempt))]
+        write!(f, "Span")
+    }
+}
+
 #[derive(Copy, Clone)]
 pub struct Term {
     intern: usize,
@@ -466,7 +483,11 @@
 
 impl fmt::Debug for Term {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_tuple("Term").field(&self.as_str()).finish()
+        let mut debug = f.debug_struct("Term");
+        debug.field("sym", &format_args!("{}", self.as_str()));
+        #[cfg(procmacro2_semver_exempt)]
+        debug.field("span", &self.span);
+        debug.finish()
     }
 }
 
@@ -508,7 +529,7 @@
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub struct Literal {
     text: String,
     span: Span,
@@ -629,6 +650,16 @@
     }
 }
 
+impl fmt::Debug for Literal {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Literal");
+        debug.field("lit", &format_args!("{}", self.text));
+        #[cfg(procmacro2_semver_exempt)]
+        debug.field("span", &self.span);
+        debug.finish()
+    }
+}
+
 fn token_stream(mut input: Cursor) -> PResult<::TokenStream> {
     let mut trees = Vec::new();
     loop {