Auto merge of #51862 - estebank:lifetime-spans, r=nikomatsakis

Point to lifetime spans on lifetime errors

src/librustc/hir/map/mod.rs

@@ -25,7 +25,7 @@ use rustc_target::spec::abi::Abi;
 use syntax::ast::{self, Name, NodeId, CRATE_NODE_ID};
 use syntax::codemap::Spanned;
 use syntax::ext::base::MacroKind;
-use syntax_pos::Span;
+use syntax_pos::{Span, DUMMY_SP};
 
 use hir::*;
 use hir::print::Nested;
@@ -664,6 +664,33 @@ impl<'hir> Map<'hir> {
         self.as_local_node_id(id).map(|id| self.get(id)) // read recorded by `get`
     }
 
+    pub fn get_generics(&self, id: DefId) -> Option<&'hir Generics> {
+        self.get_if_local(id).and_then(|node| {
+            match node {
+                NodeImplItem(ref impl_item) => Some(&impl_item.generics),
+                NodeTraitItem(ref trait_item) => Some(&trait_item.generics),
+                NodeItem(ref item) => {
+                    match item.node {
+                        ItemFn(_, _, ref generics, _) |
+                        ItemTy(_, ref generics) |
+                        ItemEnum(_, ref generics) |
+                        ItemStruct(_, ref generics) |
+                        ItemUnion(_, ref generics) |
+                        ItemTrait(_, _, ref generics, ..) |
+                        ItemTraitAlias(ref generics, _) |
+                        ItemImpl(_, _, _, ref generics, ..) => Some(generics),
+                        _ => None,
+                    }
+                }
+                _ => None,
+            }
+        })
+    }
+
+    pub fn get_generics_span(&self, id: DefId) -> Option<Span> {
+        self.get_generics(id).map(|generics| generics.span).filter(|sp| *sp != DUMMY_SP)
+    }
+
     /// Retrieve the Node corresponding to `id`, returning None if
     /// cannot be found.
     pub fn find(&self, id: NodeId) -> Option<Node<'hir>> {

src/librustc/hir/mod.rs

@@ -31,7 +31,7 @@ use hir::def_id::{DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX};
 use util::nodemap::{NodeMap, FxHashSet};
 use mir::mono::Linkage;
 
-use syntax_pos::{Span, DUMMY_SP};
+use syntax_pos::{Span, DUMMY_SP, symbol::InternedString};
 use syntax::codemap::{self, Spanned};
 use rustc_target::spec::abi::Abi;
 use syntax::ast::{self, CrateSugar, Ident, Name, NodeId, DUMMY_NODE_ID, AsmDialect};
@@ -547,6 +547,15 @@ impl Generics {
 
         own_counts
     }
+
+    pub fn get_named(&self, name: &InternedString) -> Option<&GenericParam> {
+        for param in &self.params {
+            if *name == param.name.ident().as_interned_str() {
+                return Some(param);
+            }
+        }
+        None
+    }
 }
 
 /// Synthetic Type Parameters are converted to an other form during lowering, this allows

src/librustc/infer/error_reporting/mod.rs

@@ -189,6 +189,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         self,
         region: ty::Region<'tcx>,
     ) -> (String, Option<Span>) {
+        let cm = self.sess.codemap();
+
         let scope = region.free_region_binding_scope(self);
         let node = self.hir.as_local_node_id(scope).unwrap_or(DUMMY_NODE_ID);
         let unknown;
@@ -219,10 +221,26 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             }
         };
         let (prefix, span) = match *region {
-            ty::ReEarlyBound(ref br) => (
-                format!("the lifetime {} as defined on", br.name),
-                self.sess.codemap().def_span(self.hir.span(node)),
-            ),
+            ty::ReEarlyBound(ref br) => {
+                let mut sp = cm.def_span(self.hir.span(node));
+                if let Some(param) = self.hir.get_generics(scope).and_then(|generics| {
+                    generics.get_named(&br.name)
+                }) {
+                    sp = param.span;
+                }
+                (format!("the lifetime {} as defined on", br.name), sp)
+            }
+            ty::ReFree(ty::FreeRegion {
+                bound_region: ty::BoundRegion::BrNamed(_, ref name), ..
+            }) => {
+                let mut sp = cm.def_span(self.hir.span(node));
+                if let Some(param) = self.hir.get_generics(scope).and_then(|generics| {
+                    generics.get_named(&name)
+                }) {
+                    sp = param.span;
+                }
+                (format!("the lifetime {} as defined on", name), sp)
+            }
             ty::ReFree(ref fr) => match fr.bound_region {
                 ty::BrAnon(idx) => (
                     format!("the anonymous lifetime #{} defined on", idx + 1),
@@ -234,7 +252,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 ),
                 _ => (
                     format!("the lifetime {} as defined on", fr.bound_region),
-                    self.sess.codemap().def_span(self.hir.span(node)),
+                    cm.def_span(self.hir.span(node)),
                 ),
             },
             _ => bug!(),

src/librustc_typeck/check/compare_method.rs

@@ -356,7 +356,6 @@ fn check_region_bounds_on_impl_method<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                                 impl_generics: &ty::Generics,
                                                 trait_to_skol_substs: &Substs<'tcx>)
                                                 -> Result<(), ErrorReported> {
-    let span = tcx.sess.codemap().def_span(span);
     let trait_params = trait_generics.own_counts().lifetimes;
     let impl_params = impl_generics.own_counts().lifetimes;
 
@@ -378,16 +377,20 @@ fn check_region_bounds_on_impl_method<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // are zero. Since I don't quite know how to phrase things at
     // the moment, give a kind of vague error message.
     if trait_params != impl_params {
-        let mut err = struct_span_err!(tcx.sess,
-                                       span,
-                                       E0195,
-                                       "lifetime parameters or bounds on method `{}` do not match \
-                                        the trait declaration",
-                                       impl_m.ident);
+        let def_span = tcx.sess.codemap().def_span(span);
+        let span = tcx.hir.get_generics_span(impl_m.def_id).unwrap_or(def_span);
+        let mut err = struct_span_err!(
+            tcx.sess,
+            span,
+            E0195,
+            "lifetime parameters or bounds on method `{}` do not match the trait declaration",
+            impl_m.ident,
+        );
         err.span_label(span, "lifetimes do not match method in trait");
         if let Some(sp) = tcx.hir.span_if_local(trait_m.def_id) {
-            err.span_label(tcx.sess.codemap().def_span(sp),
-                           "lifetimes in impl do not match this method in trait");
+            let def_sp = tcx.sess.codemap().def_span(sp);
+            let sp = tcx.hir.get_generics_span(trait_m.def_id).unwrap_or(def_sp);
+            err.span_label(sp, "lifetimes in impl do not match this method in trait");
         }
         err.emit();
         return Err(ErrorReported);

src/test/ui/associated-const-impl-wrong-lifetime.stderr

@@ -6,11 +6,11 @@ LL |     const NAME: &'a str = "unit";
    |
    = note: expected type `&'static str`
               found type `&'a str`
-note: the lifetime 'a as defined on the impl at 17:1...
-  --> $DIR/associated-const-impl-wrong-lifetime.rs:17:1
+note: the lifetime 'a as defined on the impl at 17:6...
+  --> $DIR/associated-const-impl-wrong-lifetime.rs:17:6
    |
 LL | impl<'a> Foo for &'a () {
-   | ^^^^^^^^^^^^^^^^^^^^^^^
+   |      ^^
    = note: ...does not necessarily outlive the static lifetime
 
 error: aborting due to previous error

src/test/ui/borrowck/borrowck-escaping-closure-error-2.nll.stderr

@@ -7,11 +7,11 @@ LL |     //~^ ERROR E0373
 LL | }
    | - borrowed value only lives until here
    |
-note: borrowed value must be valid for the lifetime 'a as defined on the function body at 19:1...
-  --> $DIR/borrowck-escaping-closure-error-2.rs:19:1
+note: borrowed value must be valid for the lifetime 'a as defined on the function body at 19:8...
+  --> $DIR/borrowck-escaping-closure-error-2.rs:19:8
    |
 LL | fn foo<'a>(x: &'a i32) -> Box<FnMut()+'a> {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^
 
 error: aborting due to previous error
 

src/test/ui/borrowck/regions-bound-missing-bound-in-impl.rs

@@ -20,6 +20,7 @@ pub trait Foo<'a, 't> {
     fn no_bound<'b>(self, b: Inv<'b>);
     fn has_bound<'b:'a>(self, b: Inv<'b>);
     fn wrong_bound1<'b,'c,'d:'a+'b>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>);
+    fn wrong_bound2<'b,'c,'d:'a+'b>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>);
     fn okay_bound<'b,'c,'d:'a+'b+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>);
     fn another_bound<'x: 'a>(self, x: Inv<'x>, y: Inv<'t>);
 }
@@ -47,6 +48,10 @@ impl<'a, 't> Foo<'a, 't> for &'a isize {
         // cases.
     }
 
+    fn wrong_bound2(self, b: Inv, c: Inv, d: Inv) {
+        //~^ ERROR lifetime parameters or bounds on method `wrong_bound2` do not match the trait
+    }
+
     fn okay_bound<'b,'c,'e:'b+'c>(self, b: Inv<'b>, c: Inv<'c>, e: Inv<'e>) {
     }
 

src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr

@@ -1,50 +1,59 @@
 error[E0195]: lifetime parameters or bounds on method `no_bound` do not match the trait declaration
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:28:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:29:16
    |
 LL |     fn no_bound<'b>(self, b: Inv<'b>);
-   |     ---------------------------------- lifetimes in impl do not match this method in trait
+   |                ---- lifetimes in impl do not match this method in trait
 ...
 LL |     fn no_bound<'b:'a>(self, b: Inv<'b>) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
+   |                ^^^^^^^ lifetimes do not match method in trait
 
 error[E0195]: lifetime parameters or bounds on method `has_bound` do not match the trait declaration
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:32:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:33:17
    |
 LL |     fn has_bound<'b:'a>(self, b: Inv<'b>);
-   |     -------------------------------------- lifetimes in impl do not match this method in trait
+   |                 ------- lifetimes in impl do not match this method in trait
 ...
 LL |     fn has_bound<'b>(self, b: Inv<'b>) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
+   |                 ^^^^ lifetimes do not match method in trait
 
 error[E0308]: method not compatible with trait
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:36:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:37:5
    |
 LL |     fn wrong_bound1<'b,'c,'d:'a+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
    |
    = note: expected type `fn(&'a isize, Inv<'c>, Inv<'c>, Inv<'d>)`
               found type `fn(&'a isize, Inv<'_>, Inv<'c>, Inv<'d>)`
-note: the lifetime 'c as defined on the method body at 36:5...
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:36:5
+note: the lifetime 'c as defined on the method body at 37:24...
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:37:24
    |
 LL |     fn wrong_bound1<'b,'c,'d:'a+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...does not necessarily outlive the lifetime 'c as defined on the method body at 36:5
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:36:5
+   |                        ^^
+note: ...does not necessarily outlive the lifetime 'c as defined on the method body at 37:24
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:37:24
    |
 LL |     fn wrong_bound1<'b,'c,'d:'a+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                        ^^
+
+error[E0195]: lifetime parameters or bounds on method `wrong_bound2` do not match the trait declaration
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:51:5
+   |
+LL |     fn wrong_bound2<'b,'c,'d:'a+'b>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>);
+   |                    ---------------- lifetimes in impl do not match this method in trait
+...
+LL |     fn wrong_bound2(self, b: Inv, c: Inv, d: Inv) {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:53:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:58:5
    |
 LL |     fn another_bound<'x: 'a>(self, x: Inv<'x>, y: Inv<'t>);
    |     ------------------------------------------------------- definition of `another_bound` from trait
 ...
 LL |     fn another_bound<'x: 't>(self, x: Inv<'x>, y: Inv<'t>) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `'x: 't`
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
 Some errors occurred: E0195, E0276, E0308.
 For more information about an error, try `rustc --explain E0195`.

src/test/ui/closure-expected-type/expect-region-supply-region.stderr

@@ -38,11 +38,11 @@ LL | |
 LL | |         //~^ ERROR borrowed data cannot be stored outside of its closure
 LL | |     });
    | |_____^
-note: ...does not necessarily outlive the lifetime 'x as defined on the function body at 42:1
-  --> $DIR/expect-region-supply-region.rs:42:1
+note: ...does not necessarily outlive the lifetime 'x as defined on the function body at 42:30
+  --> $DIR/expect-region-supply-region.rs:42:30
    |
 LL | fn expect_bound_supply_named<'x>() {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                              ^^
 
 error[E0308]: mismatched types
   --> $DIR/expect-region-supply-region.rs:47:33
@@ -52,11 +52,11 @@ LL |     closure_expecting_bound(|x: &'x u32| {
    |
    = note: expected type `&u32`
               found type `&'x u32`
-note: the lifetime 'x as defined on the function body at 42:1...
-  --> $DIR/expect-region-supply-region.rs:42:1
+note: the lifetime 'x as defined on the function body at 42:30...
+  --> $DIR/expect-region-supply-region.rs:42:30
    |
 LL | fn expect_bound_supply_named<'x>() {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                              ^^
 note: ...does not necessarily outlive the anonymous lifetime #2 defined on the body at 47:29
   --> $DIR/expect-region-supply-region.rs:47:29
    |

src/test/ui/error-codes/E0195.stderr

@@ -1,11 +1,11 @@
 error[E0195]: lifetime parameters or bounds on method `bar` do not match the trait declaration
-  --> $DIR/E0195.rs:19:5
+  --> $DIR/E0195.rs:19:11
    |
 LL |     fn bar<'a,'b:'a>(x: &'a str, y: &'b str);
-   |     ----------------------------------------- lifetimes in impl do not match this method in trait
+   |           ---------- lifetimes in impl do not match this method in trait
 ...
 LL |     fn bar<'a,'b>(x: &'a str, y: &'b str) { //~ ERROR E0195
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
+   |           ^^^^^^^ lifetimes do not match method in trait
 
 error: aborting due to previous error
 

src/test/ui/error-codes/E0478.stderr

@@ -4,16 +4,16 @@ error[E0478]: lifetime bound not satisfied
 LL |     child: Box<Wedding<'kiss> + 'SnowWhite>, //~ ERROR E0478
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-note: lifetime parameter instantiated with the lifetime 'SnowWhite as defined on the struct at 13:1
-  --> $DIR/E0478.rs:13:1
+note: lifetime parameter instantiated with the lifetime 'SnowWhite as defined on the struct at 13:22
+  --> $DIR/E0478.rs:13:22
    |
 LL | struct Prince<'kiss, 'SnowWhite> {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: but lifetime parameter must outlive the lifetime 'kiss as defined on the struct at 13:1
-  --> $DIR/E0478.rs:13:1
+   |                      ^^^^^^^^^^
+note: but lifetime parameter must outlive the lifetime 'kiss as defined on the struct at 13:15
+  --> $DIR/E0478.rs:13:15
    |
 LL | struct Prince<'kiss, 'SnowWhite> {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |               ^^^^^
 
 error: aborting due to previous error
 

src/test/ui/impl-trait/region-escape-via-bound.stderr

@@ -4,16 +4,11 @@ error[E0700]: hidden type for `impl Trait` captures lifetime that does not appea
 LL | fn foo(x: Cell<&'x u32>) -> impl Trait<'y>
    |                             ^^^^^^^^^^^^^^
    |
-note: hidden type `std::cell::Cell<&'x u32>` captures the lifetime 'x as defined on the function body at 26:1
-  --> $DIR/region-escape-via-bound.rs:26:1
+note: hidden type `std::cell::Cell<&'x u32>` captures the lifetime 'x as defined on the function body at 28:7
+  --> $DIR/region-escape-via-bound.rs:28:7
    |
-LL | / fn foo(x: Cell<&'x u32>) -> impl Trait<'y>
-LL | |     //~^ ERROR hidden type for `impl Trait` captures lifetime that does not appear in bounds [E0700]
-LL | | where 'x: 'y
-LL | | {
-LL | |     x
-LL | | }
-   | |_^
+LL | where 'x: 'y
+   |       ^^
 
 error: aborting due to previous error
 

src/test/ui/impl-trait/static-return-lifetime-infered.stderr

@@ -30,12 +30,12 @@ LL |         self.x.iter().map(|a| a.0)
    |         |
    |         ...but this borrow...
    |
-note: ...can't outlive the lifetime 'a as defined on the method body at 20:5
-  --> $DIR/static-return-lifetime-infered.rs:20:5
+note: ...can't outlive the lifetime 'a as defined on the method body at 20:20
+  --> $DIR/static-return-lifetime-infered.rs:20:20
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: you can add a constraint to the return type to make it last less than `'static` and match the lifetime 'a as defined on the method body at 20:5
+   |                    ^^
+help: you can add a constraint to the return type to make it last less than `'static` and match the lifetime 'a as defined on the method body at 20:20
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/in-band-lifetimes/impl/dyn-trait.stderr

@@ -4,11 +4,11 @@ error[E0495]: cannot infer an appropriate lifetime due to conflicting requiremen
 LL |     static_val(x); //~ ERROR cannot infer
    |                ^
    |
-note: first, the lifetime cannot outlive the lifetime 'a as defined on the function body at 31:1...
-  --> $DIR/dyn-trait.rs:31:1
+note: first, the lifetime cannot outlive the lifetime 'a as defined on the function body at 31:26...
+  --> $DIR/dyn-trait.rs:31:26
    |
 LL | fn with_dyn_debug_static<'a>(x: Box<dyn Debug + 'a>) {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                          ^^
    = note: ...so that the expression is assignable:
            expected std::boxed::Box<dyn std::fmt::Debug>
               found std::boxed::Box<(dyn std::fmt::Debug + 'a)>