enhance check_pat_lit with TopInfo

Author: Centril

src/librustc_typeck/check/demand.rs

@@ -43,7 +43,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
     ) -> Option<DiagnosticBuilder<'tcx>> {
-        let cause = &self.misc(sp);
+        self.demand_suptype_with_origin(&self.misc(sp), expected, actual)
+    }
+
+    pub fn demand_suptype_with_origin(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        expected: Ty<'tcx>,
+        actual: Ty<'tcx>,
+    ) -> Option<DiagnosticBuilder<'tcx>> {
         match self.at(cause, self.param_env).sup(expected, actual) {
             Ok(InferOk { obligations, value: () }) => {
                 self.register_predicates(obligations);

src/librustc_typeck/check/pat.rs

@@ -9,7 +9,7 @@ use rustc_hir::pat_util::EnumerateAndAdjustIterator;
 use rustc_hir::{HirId, Pat, PatKind};
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::traits::Pattern;
+use rustc_infer::traits::{ObligationCause, Pattern};
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::{Span, Spanned};
 use syntax::ast;
@@ -66,16 +66,19 @@ struct TopInfo<'tcx> {
 }
 
 impl<'tcx> FnCtxt<'_, 'tcx> {
+    fn pattern_cause(&self, ti: TopInfo<'tcx>, cause_span: Span) -> ObligationCause<'tcx> {
+        let code = Pattern { span: ti.span, root_ty: ti.expected, origin_expr: ti.origin_expr };
+        self.cause(cause_span, code)
+    }
+
     fn demand_eqtype_pat_diag(
         &self,
         cause_span: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
         ti: TopInfo<'tcx>,
     ) -> Option<DiagnosticBuilder<'tcx>> {
-        let code = Pattern { span: ti.span, root_ty: ti.expected, origin_expr: ti.origin_expr };
-        let cause = self.cause(cause_span, code);
-        self.demand_eqtype_with_origin(&cause, expected, actual)
+        self.demand_eqtype_with_origin(&self.pattern_cause(ti, cause_span), expected, actual)
     }
 
     fn demand_eqtype_pat(
@@ -379,7 +382,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         //     &'static str <: expected
         //
         // then that's equivalent to there existing a LUB.
-        if let Some(mut err) = self.demand_suptype_diag(span, expected, pat_ty) {
+        let cause = self.pattern_cause(ti, span);
+        if let Some(mut err) = self.demand_suptype_with_origin(&cause, expected, pat_ty) {
             err.emit_unless(
                 ti.span
                     .filter(|&s| {

src/test/ui/match/match-ill-type2.stderr

@@ -1,6 +1,9 @@
 error[E0308]: mismatched types
   --> $DIR/match-ill-type2.rs:4:9
    |
+LL |     match 1i32 {
+   |           ---- this expression has type `i32`
+LL |         1i32 => 1,
 LL |         2u32 => 1,
    |         ^^^^ expected `i32`, found `u32`
 

src/test/ui/rfc-2005-default-binding-mode/lit.stderr

@@ -1,6 +1,8 @@
 error[E0308]: mismatched types
   --> $DIR/lit.rs:7:13
    |
+LL |     match &s {
+   |           -- this expression has type `&&str`
 LL |             "abc" => true,
    |             ^^^^^ expected `&str`, found `str`
    |
@@ -10,6 +12,8 @@ LL |             "abc" => true,
 error[E0308]: mismatched types
   --> $DIR/lit.rs:16:9
    |
+LL |     match &s {
+   |           -- this expression has type `&&[u8]`
 LL |         b"abc" => true,
    |         ^^^^^^ expected `&[u8]`, found array `[u8; 3]`
    |

src/test/ui/slightly-nice-generic-literal-messages.stderr

@@ -1,6 +1,8 @@
 error[E0308]: mismatched types
   --> $DIR/slightly-nice-generic-literal-messages.rs:7:9
    |
+LL |     match Foo(1.1, marker::PhantomData) {
+   |           ----------------------------- this expression has type `Foo<{float}, _>`
 LL |         1 => {}
    |         ^ expected struct `Foo`, found integer
    |