Use the span of the user type for AscribeUserType

matthewjasper · matthewjasper · commit 55ec10431318 · 2018-10-10T11:56:16.000+01:00
Also change the order of the fake read for let and the AscribeUserType,
so that we use the better span and message from the fake read in errors.
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
@@ -710,7 +710,7 @@ pub struct LocalDecl<'tcx> {
     /// e.g. via `let x: T`, then we carry that type here. The MIR
     /// borrow checker needs this information since it can affect
     /// region inference.
-    pub user_ty: Option<CanonicalTy<'tcx>>,
+    pub user_ty: Option<(CanonicalTy<'tcx>, Span)>,
 
     /// Name of the local, used in debuginfo and pretty-printing.
     ///
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
@@ -735,7 +735,7 @@ macro_rules! make_mir_visitor {
                     local,
                     source_info: *source_info,
                 });
-                if let Some(user_ty) = user_ty {
+                if let Some((user_ty, _)) = user_ty {
                     self.visit_user_ty(user_ty);
                 }
                 self.visit_source_info(source_info);
diff --git a/src/librustc_mir/borrow_check/nll/type_check/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
@@ -310,12 +310,12 @@ impl<'a, 'b, 'gcx, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'gcx, 'tcx> {
         self.super_local_decl(local, local_decl);
         self.sanitize_type(local_decl, local_decl.ty);
 
-        if let Some(user_ty) = local_decl.user_ty {
+        if let Some((user_ty, span)) = local_decl.user_ty {
             if let Err(terr) = self.cx.relate_type_and_user_type(
                 local_decl.ty,
                 ty::Variance::Invariant,
                 user_ty,
-                Locations::All(local_decl.source_info.span),
+                Locations::All(span),
                 ConstraintCategory::TypeAnnotation,
             ) {
                 span_mirbug!(
diff --git a/src/librustc_mir/build/matches/mod.rs b/src/librustc_mir/build/matches/mod.rs
@@ -292,30 +292,32 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     ..
                 },
                 user_ty: ascription_user_ty,
+                user_ty_span,
             } => {
                 let place =
                     self.storage_live_binding(block, var, irrefutable_pat.span, OutsideGuard);
                 unpack!(block = self.into(&place, block, initializer));
 
-                let source_info = self.source_info(irrefutable_pat.span);
+                // Inject a fake read, see comments on `FakeReadCause::ForLet`.
+                let pattern_source_info = self.source_info(irrefutable_pat.span);
                 self.cfg.push(
                     block,
                     Statement {
-                        source_info,
-                        kind: StatementKind::AscribeUserType(
-                            place.clone(),
-                            ty::Variance::Invariant,
-                            ascription_user_ty,
-                        ),
+                        source_info: pattern_source_info,
+                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, place.clone()),
                     },
                 );
 
-                // Inject a fake read, see comments on `FakeReadCause::ForLet`.
+                let ty_source_info = self.source_info(user_ty_span);
                 self.cfg.push(
                     block,
                     Statement {
-                        source_info,
-                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, place.clone()),
+                        source_info: ty_source_info,
+                        kind: StatementKind::AscribeUserType(
+                            place.clone(),
+                            ty::Variance::Invariant,
+                            ascription_user_ty,
+                        ),
                     },
                 );
 
@@ -489,7 +491,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
     pub fn visit_bindings(
         &mut self,
         pattern: &Pattern<'tcx>,
-        mut pattern_user_ty: Option<CanonicalTy<'tcx>>,
+        mut pattern_user_ty: Option<(CanonicalTy<'tcx>, Span)>,
         f: &mut impl FnMut(
             &mut Self,
             Mutability,
@@ -498,7 +500,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             NodeId,
             Span,
             Ty<'tcx>,
-            Option<CanonicalTy<'tcx>>,
+            Option<(CanonicalTy<'tcx>, Span)>,
         ),
     ) {
         match *pattern.kind {
@@ -549,16 +551,15 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 // FIXME(#47184): extract or handle `pattern_user_ty` somehow
                 self.visit_bindings(subpattern, None, f);
             }
-            PatternKind::AscribeUserType { ref subpattern, user_ty } => {
+            PatternKind::AscribeUserType { ref subpattern, user_ty, user_ty_span } => {
                 // This corresponds to something like
                 //
                 // ```
-                // let (p1: T1): T2 = ...;
+                // let A::<'a>(_): A<'static> = ...;
                 // ```
                 //
-                // Not presently possible, though maybe someday.
-                assert!(pattern_user_ty.is_none());
-                self.visit_bindings(subpattern, Some(user_ty), f)
+                // FIXME(#47184): handle `pattern_user_ty` somehow
+                self.visit_bindings(subpattern, Some((user_ty, user_ty_span)), f)
             }
             PatternKind::Leaf { ref subpatterns }
             | PatternKind::Variant {
@@ -1469,7 +1470,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         num_patterns: usize,
         var_id: NodeId,
         var_ty: Ty<'tcx>,
-        user_var_ty: Option<CanonicalTy<'tcx>>,
+        user_var_ty: Option<(CanonicalTy<'tcx>, Span)>,
         has_guard: ArmHasGuard,
         opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
         pat_span: Span,
diff --git a/src/librustc_mir/build/matches/simplify.rs b/src/librustc_mir/build/matches/simplify.rs
@@ -63,9 +63,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                                  candidate: &mut Candidate<'pat, 'tcx>)
                                  -> Result<(), MatchPair<'pat, 'tcx>> {
         match *match_pair.pattern.kind {
-            PatternKind::AscribeUserType { ref subpattern, user_ty } => {
+            PatternKind::AscribeUserType { ref subpattern, user_ty, user_ty_span } => {
                 candidate.ascriptions.push(Ascription {
-                    span: match_pair.pattern.span,
+                    span: user_ty_span,
                     user_ty,
                     source: match_pair.place.clone(),
                 });
diff --git a/src/librustc_mir/hair/cx/block.rs b/src/librustc_mir/hair/cx/block.rs
@@ -92,6 +92,7 @@ fn mirror_stmts<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
                                     span: pattern.span,
                                     kind: Box::new(PatternKind::AscribeUserType {
                                         user_ty: *user_ty,
+                                        user_ty_span: ty.span,
                                         subpattern: pattern
                                     })
                                 };
diff --git a/src/librustc_mir/hair/pattern/mod.rs b/src/librustc_mir/hair/pattern/mod.rs
@@ -71,6 +71,7 @@ pub enum PatternKind<'tcx> {
     AscribeUserType {
         user_ty: CanonicalTy<'tcx>,
         subpattern: Pattern<'tcx>,
+        user_ty_span: Span,
     },
 
     /// x, ref x, x @ P, etc
@@ -692,6 +693,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
             kind = PatternKind::AscribeUserType {
                 subpattern,
                 user_ty,
+                user_ty_span: span,
             };
         }
 
@@ -1015,9 +1017,11 @@ impl<'tcx> PatternFoldable<'tcx> for PatternKind<'tcx> {
             PatternKind::AscribeUserType {
                 ref subpattern,
                 user_ty,
+                user_ty_span,
             } => PatternKind::AscribeUserType {
                 subpattern: subpattern.fold_with(folder),
                 user_ty: user_ty.fold_with(folder),
+                user_ty_span,
             },
             PatternKind::Binding {
                 mutability,
diff --git a/src/test/mir-opt/basic_assignment.rs b/src/test/mir-opt/basic_assignment.rs
@@ -55,8 +55,8 @@ fn main() {
 //        StorageDead(_3);
 //        StorageLive(_4);
 //        _4 = std::option::Option<std::boxed::Box<u32>>::None;
-//        AscribeUserType(_4, o, Canonical { variables: [], value: std::option::Option<std::boxed::Box<u32>> });
 //        FakeRead(ForLet, _4);
+//        AscribeUserType(_4, o, Canonical { variables: [], value: std::option::Option<std::boxed::Box<u32>> });
 //        StorageLive(_5);
 //        StorageLive(_6);
 //        _6 = move _4;
diff --git a/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr b/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr
@@ -5,10 +5,10 @@ LL |     let a: for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32 = make_it();
    |                                                          ^^^^^^^^^
 
 error: higher-ranked subtype error
-  --> $DIR/hr-fn-aaa-as-aba.rs:32:9
+  --> $DIR/hr-fn-aaa-as-aba.rs:32:12
    |
 LL |     let _: for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32 = make_it();
-   |         ^
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/nll/user-annotations/patterns.stderr b/src/test/ui/nll/user-annotations/patterns.stderr
@@ -131,12 +131,12 @@ LL |     y //~ ERROR
    |     ^ returning this value requires that `'a` must outlive `'static`
 
 error: unsatisfied lifetime constraints
-  --> $DIR/patterns.rs:117:9
+  --> $DIR/patterns.rs:117:18
    |
 LL | fn a_to_static_then_static<'a>(x: &'a u32) -> &'static u32 {
    |                            -- lifetime `'a` defined here
 LL |     let (y, _z): (&'static u32, u32) = (x, 44); //~ ERROR
-   |         ^^^^^^^ type annotation requires that `'a` must outlive `'static`
+   |                  ^^^^^^^^^^^^^^^^^^^ type annotation requires that `'a` must outlive `'static`
 
 error: aborting due to 14 previous errors
 
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr
@@ -1,10 +1,10 @@
 error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/region-object-lifetime-in-coercion.rs:18:9
+  --> $DIR/region-object-lifetime-in-coercion.rs:18:12
    |
 LL | fn a(v: &[u8]) -> Box<Foo + 'static> {
    |         ----- help: add explicit lifetime `'static` to the type of `v`: `&'static [u8]`
 LL |     let x: Box<Foo + 'static> = Box::new(v);
-   |         ^ lifetime `'static` required
+   |            ^^^^^^^^^^^^^^^^^^ lifetime `'static` required
 
 error[E0621]: explicit lifetime required in the type of `v`
   --> $DIR/region-object-lifetime-in-coercion.rs:24:5
diff --git a/src/test/ui/regions/regions-addr-of-self.nll.stderr b/src/test/ui/regions/regions-addr-of-self.nll.stderr
@@ -1,10 +1,10 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-addr-of-self.rs:17:13
+  --> $DIR/regions-addr-of-self.rs:17:16
    |
 LL |     pub fn chase_cat(&mut self) {
    |                      - let's call the lifetime of this reference `'1`
 LL |         let p: &'static mut usize = &mut self.cats_chased; //~ ERROR cannot infer
-   |             ^ type annotation requires that `'1` must outlive `'static`
+   |                ^^^^^^^^^^^^^^^^^^ type annotation requires that `'1` must outlive `'static`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-addr-of-upvar-self.nll.stderr b/src/test/ui/regions/regions-addr-of-upvar-self.nll.stderr
@@ -1,33 +1,33 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-addr-of-upvar-self.rs:20:17
+  --> $DIR/regions-addr-of-upvar-self.rs:20:20
    |
 LL |         let _f = || {
    |                  -- lifetime `'1` represents this closure's body
 LL |             let p: &'static mut usize = &mut self.food; //~ ERROR cannot infer
-   |                 ^ type annotation requires that `'1` must outlive `'static`
+   |                    ^^^^^^^^^^^^^^^^^^ type annotation requires that `'1` must outlive `'static`
    |
    = note: closure implements `FnMut`, so references to captured variables can't escape the closure
 
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-addr-of-upvar-self.rs:20:17
+  --> $DIR/regions-addr-of-upvar-self.rs:20:20
    |
 LL |     pub fn chase_cat(&mut self) {
    |                      --------- lifetime `'2` appears in the type of `self`
 LL |         let _f = || {
    |                  -- lifetime `'1` represents this closure's body
 LL |             let p: &'static mut usize = &mut self.food; //~ ERROR cannot infer
-   |                 ^ type annotation requires that `'1` must outlive `'2`
+   |                    ^^^^^^^^^^^^^^^^^^ type annotation requires that `'1` must outlive `'2`
    |
    = note: closure implements `FnMut`, so references to captured variables can't escape the closure
 
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-addr-of-upvar-self.rs:20:17
+  --> $DIR/regions-addr-of-upvar-self.rs:20:20
    |
 LL |     pub fn chase_cat(&mut self) {
    |                      - let's call the lifetime of this reference `'1`
 LL |         let _f = || {
 LL |             let p: &'static mut usize = &mut self.food; //~ ERROR cannot infer
-   |                 ^ type annotation requires that `'1` must outlive `'static`
+   |                    ^^^^^^^^^^^^^^^^^^ type annotation requires that `'1` must outlive `'static`
 
 error[E0597]: `self` does not live long enough
   --> $DIR/regions-addr-of-upvar-self.rs:20:46
diff --git a/src/test/ui/regions/regions-infer-contravariance-due-to-decl.nll.stderr b/src/test/ui/regions/regions-infer-contravariance-due-to-decl.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-infer-contravariance-due-to-decl.rs:35:9
+  --> $DIR/regions-infer-contravariance-due-to-decl.rs:35:12
    |
 LL | fn use_<'short,'long>(c: Contravariant<'short>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: Contravariant<'long> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-infer-covariance-due-to-decl.nll.stderr b/src/test/ui/regions/regions-infer-covariance-due-to-decl.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-infer-covariance-due-to-decl.rs:32:9
+  --> $DIR/regions-infer-covariance-due-to-decl.rs:32:12
    |
 LL | fn use_<'short,'long>(c: Covariant<'long>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: Covariant<'short> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-variance-contravariant-use-covariant-in-second-position.nll.stderr b/src/test/ui/regions/regions-variance-contravariant-use-covariant-in-second-position.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-variance-contravariant-use-covariant-in-second-position.rs:35:9
+  --> $DIR/regions-variance-contravariant-use-covariant-in-second-position.rs:35:12
    |
 LL | fn use_<'short,'long>(c: S<'long, 'short>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: S<'long, 'long> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-variance-contravariant-use-covariant.nll.stderr b/src/test/ui/regions/regions-variance-contravariant-use-covariant.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-variance-contravariant-use-covariant.rs:33:9
+  --> $DIR/regions-variance-contravariant-use-covariant.rs:33:12
    |
 LL | fn use_<'short,'long>(c: Contravariant<'short>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: Contravariant<'long> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-variance-covariant-use-contravariant.nll.stderr b/src/test/ui/regions/regions-variance-covariant-use-contravariant.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-variance-covariant-use-contravariant.rs:33:9
+  --> $DIR/regions-variance-covariant-use-contravariant.rs:33:12
    |
 LL | fn use_<'short,'long>(c: Covariant<'long>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: Covariant<'short> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-variance-invariant-use-contravariant.nll.stderr b/src/test/ui/regions/regions-variance-invariant-use-contravariant.nll.stderr
@@ -1,13 +1,13 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-variance-invariant-use-contravariant.rs:30:9
+  --> $DIR/regions-variance-invariant-use-contravariant.rs:30:12
    |
 LL | fn use_<'short,'long>(c: Invariant<'long>,
    |         ------ ----- lifetime `'long` defined here
    |         |
    |         lifetime `'short` defined here
 ...
 LL |     let _: Invariant<'short> = c; //~ ERROR E0623
-   |         ^ type annotation requires that `'short` must outlive `'long`
+   |            ^^^^^^^^^^^^^^^^^ type annotation requires that `'short` must outlive `'long`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-variance-invariant-use-covariant.nll.stderr b/src/test/ui/regions/regions-variance-invariant-use-covariant.nll.stderr
@@ -1,11 +1,11 @@
 error: unsatisfied lifetime constraints
-  --> $DIR/regions-variance-invariant-use-covariant.rs:27:9
+  --> $DIR/regions-variance-invariant-use-covariant.rs:27:12
    |
 LL | fn use_<'b>(c: Invariant<'b>) {
    |         -- lifetime `'b` defined here
 ...
 LL |     let _: Invariant<'static> = c; //~ ERROR mismatched types
-   |         ^ type annotation requires that `'b` must outlive `'static`
+   |            ^^^^^^^^^^^^^^^^^^ type annotation requires that `'b` must outlive `'static`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/try-block/try-block-bad-lifetime.stderr b/src/test/ui/try-block/try-block-bad-lifetime.stderr
@@ -2,7 +2,7 @@ error[E0597]: `my_string` does not live long enough
   --> $DIR/try-block-bad-lifetime.rs:25:33
    |
 LL |         let result: Result<(), &str> = try {
-   |             ------ borrow later used here
+   |             ------ borrow later stored here
 LL |             let my_string = String::from("");
 LL |             let my_str: & str = & my_string;
    |                                 ^^^^^^^^^^^ borrowed value does not live long enough
diff --git a/src/test/ui/variance/variance-cell-is-invariant.nll.stderr b/src/test/ui/variance/variance-cell-is-invariant.nll.stderr
diff --git a/src/test/ui/wf/wf-static-method.nll.stderr b/src/test/ui/wf/wf-static-method.nll.stderr

Original file line number	Diff line number	Diff line change
`@@ -735,7 +735,7 @@ macro_rules! make_mir_visitor {`
`735`	`735`	`local,`
`736`	`736`	`source_info: *source_info,`
`737`	`737`	`});`
`738`		`- if let Some(user_ty) = user_ty {`
	`738`	`+ if let Some((user_ty, _)) = user_ty {`
`739`	`739`	`self.visit_user_ty(user_ty);`
`740`	`740`	`}`
`741`	`741`	`self.visit_source_info(source_info);`
Original file line number	Diff line number	Diff line change
@@ -2,7 +2,7 @@ error[E0597]: `my_string` does not live long enough
`2`	`2`	`--> $DIR/try-block-bad-lifetime.rs:25:33`
`3`	`3`	`\|`
`4`	`4`	`LL \| let result: Result<(), &str> = try {`
`5`		`- \| ------ borrow later used here`
	`5`	`+ \| ------ borrow later stored here`
`6`	`6`	`LL \| let my_string = String::from("");`
`7`	`7`	`LL \| let my_str: & str = & my_string;`
`8`	`8`	`\| ^^^^^^^^^^^ borrowed value does not live long enough`