Use upstream 'Literal::subspan()'.

core/codegen/build.rs

@@ -8,8 +8,8 @@ use yansi::Color::{Red, Yellow, Blue};
 use version_check::{supports_features, is_min_version, is_min_date};
 
 // Specifies the minimum nightly version needed to compile Rocket.
-const MIN_DATE: &'static str = "2018-10-05";
-const MIN_VERSION: &'static str = "1.31.0-nightly";
+const MIN_DATE: &'static str = "2018-11-23";
+const MIN_VERSION: &'static str = "1.32.0-nightly";
 
 fn main() {
     let ok_channel = supports_features();

core/codegen/src/attribute/route.rs

@@ -3,7 +3,7 @@ use proc_macro2::TokenStream as TokenStream2;
 use devise::{syn, Spanned, SpanWrapped, Result, FromMeta, ext::TypeExt};
 use indexmap::IndexSet;
 
-use proc_macro_ext::{Diagnostics, SpanExt};
+use proc_macro_ext::{Diagnostics, StringLit};
 use syn_ext::{syn_to_diag, IdentExt};
 use self::syn::{Attribute, parse::Parser};
 
@@ -426,7 +426,10 @@ fn incomplete_route(
 ) -> Result<TokenStream> {
     let method_str = method.to_string().to_lowercase();
     // FIXME(proc_macro): there should be a way to get this `Span`.
-    let method_span = Span::call_site().subspan(2..2 + method_str.len()).unwrap();
+    let method_span = StringLit::new(format!("#[{}]", method), Span::call_site())
+        .subspan(2..2 + method_str.len())
+        .unwrap_or(Span::call_site());
+
     let method_ident = syn::Ident::new(&method_str, method_span.into());
 
     let function: syn::ItemFn = syn::parse(input).map_err(syn_to_diag)

core/codegen/src/attribute/segments.rs

@@ -4,7 +4,7 @@ use devise::syn;
 use proc_macro::{Span, Diagnostic};
 
 use http::route::RouteSegment;
-use proc_macro_ext::{SpanExt, Diagnostics, PResult, DResult};
+use proc_macro_ext::{Diagnostics, StringLit, PResult, DResult};
 
 crate use http::route::{Error, Kind, Source};
 
@@ -52,15 +52,16 @@ impl Hash for Segment {
 
 fn subspan(needle: &str, haystack: &str, span: Span) -> Option<Span> {
     let index = needle.as_ptr() as usize - haystack.as_ptr() as usize;
-    span.subspan(index..index + needle.len())
+    StringLit::new(haystack, span).subspan(index..index + needle.len())
 }
 
 fn trailspan(needle: &str, haystack: &str, span: Span) -> Option<Span> {
     let index = needle.as_ptr() as usize - haystack.as_ptr() as usize;
+    let lit = StringLit::new(haystack, span);
     if needle.as_ptr() as usize > haystack.as_ptr() as usize {
-        span.subspan((index - 1)..)
+        lit.subspan((index - 1)..)
     } else {
-        span.subspan(index..)
+        lit.subspan(index..)
     }
 }
 

core/codegen/src/http_codegen.rs

@@ -4,7 +4,7 @@ use devise::{FromMeta, MetaItem, Result, ext::Split2};
 use http::{self, ext::IntoOwned};
 use attribute::segments::{parse_segments, parse_segment, Segment, Kind, Source};
 
-use proc_macro_ext::SpanExt;
+use proc_macro_ext::StringLit;
 
 #[derive(Debug)]
 crate struct ContentType(crate http::ContentType);
@@ -27,6 +27,12 @@ crate struct DataSegment(crate Segment);
 #[derive(Clone, Debug)]
 crate struct Optional<T>(crate Option<T>);
 
+impl FromMeta for StringLit {
+    fn from_meta(meta: MetaItem) -> Result<Self> {
+        Ok(StringLit::new(String::from_meta(meta)?, meta.value_span()))
+    }
+}
+
 #[derive(Debug)]
 crate struct RoutePath {
     crate origin: Origin,
@@ -159,14 +165,13 @@ impl ToTokens for Method {
 
 impl FromMeta for Origin {
     fn from_meta(meta: MetaItem) -> Result<Self> {
-        let string = String::from_meta(meta)?;
-        let span = meta.value_span();
+        let string = StringLit::from_meta(meta)?;
 
         let uri = http::uri::Origin::parse_route(&string)
             .map_err(|e| {
                 let span = e.index()
-                    .map(|i| span.subspan(i + 1..).expect("origin"))
-                    .unwrap_or(span);
+                    .map(|i| string.subspan(i + 1..).expect("origin"))
+                    .unwrap_or(string.span());
 
                 span.error(format!("invalid path URI: {}", e))
                     .help("expected path in origin form: \"/path/<param>\"")
@@ -174,7 +179,7 @@ impl FromMeta for Origin {
 
         if !uri.is_normalized() {
             let normalized = uri.to_normalized();
-            return Err(span.error("paths cannot contain empty segments")
+            return Err(string.span().error("paths cannot contain empty segments")
                 .note(format!("expected '{}', found '{}'", normalized, uri)));
         }
 
@@ -184,9 +189,8 @@ impl FromMeta for Origin {
 
 impl FromMeta for Segment {
     fn from_meta(meta: MetaItem) -> Result<Self> {
-        let string = String::from_meta(meta)?;
-        let span = meta.value_span()
-            .subspan(1..(string.len() + 1))
+        let string = StringLit::from_meta(meta)?;
+        let span = string.subspan(1..(string.len() + 1))
             .expect("segment");
 
         let segment = parse_segment(&string, span)?;
@@ -210,15 +214,15 @@ impl FromMeta for DataSegment {
 
 impl FromMeta for RoutePath {
     fn from_meta(meta: MetaItem) -> Result<Self> {
-        let (origin, span) = (Origin::from_meta(meta)?, meta.value_span());
-        let path_span = span.subspan(1..origin.0.path().len() + 1).expect("path");
+        let (origin, string) = (Origin::from_meta(meta)?, StringLit::from_meta(meta)?);
+        let path_span = string.subspan(1..origin.0.path().len() + 1).expect("path");
         let path = parse_segments(origin.0.path(), '/', Source::Path, path_span);
 
         let query = origin.0.query()
             .map(|q| {
                 let len_to_q = 1 + origin.0.path().len() + 1;
                 let end_of_q = len_to_q + q.len();
-                let query_span = span.subspan(len_to_q..end_of_q).expect("query");
+                let query_span = string.subspan(len_to_q..end_of_q).expect("query");
                 if q.starts_with('&') || q.contains("&&") || q.ends_with('&') {
                     // TODO: Show a help message with what's expected.
                     Err(query_span.error("query cannot contain empty segments").into())

core/codegen/src/lib.rs

@@ -60,7 +60,7 @@
 //! ```
 
 #[macro_use] extern crate quote;
-#[macro_use] extern crate devise;
+extern crate devise;
 extern crate proc_macro;
 extern crate rocket_http as http;
 extern crate indexmap;

core/codegen/src/proc_macro_ext.rs

@@ -1,6 +1,6 @@
 use std::ops::{Bound, RangeBounds};
 
-use proc_macro::{Span, Diagnostic, /* MultiSpan */};
+use proc_macro::{Span, Diagnostic, Literal};
 use syntax_pos::{Span as InnerSpan, Pos, BytePos};
 
 pub type PResult<T> = ::std::result::Result<T, Diagnostic>;
@@ -62,42 +62,31 @@ impl From<Vec<Diagnostic>> for Diagnostics {
     }
 }
 
-pub trait SpanExt {
-    fn subspan<R: RangeBounds<usize>>(self, range: R) -> Option<Span>;
-}
+use std::ops::Deref;
 
-impl SpanExt for Span {
-    /// Create a `subspan` from `start` to `end`.
-    fn subspan<R: RangeBounds<usize>>(self, range: R) -> Option<Span> {
-        let inner: InnerSpan = unsafe { ::std::mem::transmute(self) };
-        let length = inner.hi().to_usize() - inner.lo().to_usize();
+pub struct StringLit(crate String, crate Literal);
 
-        let start = match range.start_bound() {
-            Bound::Included(&lo) => lo,
-            Bound::Excluded(&lo) => lo + 1,
-            Bound::Unbounded => 0,
-        };
+impl Deref for StringLit {
+    type Target = str;
 
-        let end = match range.end_bound() {
-            Bound::Included(&hi) => hi + 1,
-            Bound::Excluded(&hi) => hi,
-            Bound::Unbounded => length,
-        };
-
-        // Bounds check the values, preventing addition overflow and OOB spans.
-        if start > u32::max_value() as usize
-            || end > u32::max_value() as usize
-            || (u32::max_value() - start as u32) < inner.lo().to_u32()
-            || (u32::max_value() - end as u32) < inner.lo().to_u32()
-            || start >= end
-            || end > length
-        {
-            return None;
-        }
-
-        let new_lo = inner.lo() + BytePos(start as u32);
-        let new_hi = inner.lo() + BytePos(end as u32);
-        let new_inner = inner.with_lo(new_lo).with_hi(new_hi);
-        Some(unsafe { ::std::mem::transmute(new_inner) })
+    fn deref(&self) -> &str {
+        &self.0
+    }
+}
+
+impl StringLit {
+    pub fn new<S: Into<String>>(string: S, span: Span) -> Self {
+        let string = string.into();
+        let mut lit = Literal::string(&string);
+        lit.set_span(span);
+        StringLit(string, lit)
+    }
+
+    pub fn span(&self) -> Span {
+        self.1.span()
+    }
+
+    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
+        self.1.subspan(range)
     }
 }