Auto merge of #27297 - mitaa:cleanup_E0005, r=alexcrichton

This does two things:
* removes ast::LocalSource, where only one variant was used because for-loop expansion has changed. One reason that this slipped into here is because the code in `check_local` which checks for `LocalSource::LocalFor` would report the same error as in `check_exhaustive` while using the wrong error code (E0005 instead of E0297).
* silences the warning about already used diagnostic code E0005 (fixes #27279)

passes `make check` locally.

src/librustc/middle/check_match.rs

@@ -1016,18 +1016,8 @@ pub fn specialize<'a>(cx: &MatchCheckCtxt, r: &[&'a Pat],
 fn check_local(cx: &mut MatchCheckCtxt, loc: &ast::Local) {
     visit::walk_local(cx, loc);
 
-    let name = match loc.source {
+    let pat = StaticInliner::new(cx.tcx, None).fold_pat(loc.pat.clone());
-        ast::LocalLet => "local",
+    check_irrefutable(cx, &pat, false);
-        ast::LocalFor => "`for` loop"
-    };
-
-    let mut static_inliner = StaticInliner::new(cx.tcx, None);
-    is_refutable(cx, &*static_inliner.fold_pat(loc.pat.clone()), |pat| {
-        span_err!(cx.tcx.sess, loc.pat.span, E0005,
-            "refutable pattern in {} binding: `{}` not covered",
-            name, pat_to_string(pat)
-        );
-    });
 
     // Check legality of move bindings and `@` patterns.
     check_legality_of_move_bindings(cx, false, slice::ref_slice(&loc.pat));
@@ -1048,17 +1038,28 @@ fn check_fn(cx: &mut MatchCheckCtxt,
     visit::walk_fn(cx, kind, decl, body, sp);
 
     for input in &decl.inputs {
-        is_refutable(cx, &*input.pat, |pat| {
+        check_irrefutable(cx, &input.pat, true);
-            span_err!(cx.tcx.sess, input.pat.span, E0005,
-                "refutable pattern in function argument: `{}` not covered",
-                pat_to_string(pat)
-            );
-        });
         check_legality_of_move_bindings(cx, false, slice::ref_slice(&input.pat));
         check_legality_of_bindings_in_at_patterns(cx, &*input.pat);
     }
 }
 
+fn check_irrefutable(cx: &MatchCheckCtxt, pat: &Pat, is_fn_arg: bool) {
+    let origin = if is_fn_arg {
+        "function argument"
+    } else {
+        "local binding"
+    };
+
+    is_refutable(cx, pat, |uncovered_pat| {
+        span_err!(cx.tcx.sess, pat.span, E0005,
+            "refutable pattern in {}: `{}` not covered",
+            origin,
+            pat_to_string(uncovered_pat),
+        );
+    });
+}
+
 fn is_refutable<A, F>(cx: &MatchCheckCtxt, pat: &Pat, refutable: F) -> Option<A> where
     F: FnOnce(&Pat) -> A,
 {

src/libsyntax/ast.rs

@@ -29,7 +29,6 @@ pub use self::Item_::*;
 pub use self::KleeneOp::*;
 pub use self::Lit_::*;
 pub use self::LitIntType::*;
-pub use self::LocalSource::*;
 pub use self::Mac_::*;
 pub use self::MacStmtStyle::*;
 pub use self::MetaItem_::*;
@@ -756,14 +755,6 @@ pub enum MacStmtStyle {
     MacStmtWithoutBraces,
 }
 
-/// Where a local declaration came from: either a true `let ... =
-/// ...;`, or one desugared from the pattern of a for loop.
-#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
-pub enum LocalSource {
-    LocalLet,
-    LocalFor,
-}
-
 // FIXME (pending discussion of #1697, #2178...): local should really be
 // a refinement on pat.
 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
@@ -775,7 +766,6 @@ pub struct Local {
     pub init: Option<P<Expr>>,
     pub id: NodeId,
     pub span: Span,
-    pub source: LocalSource,
 }
 
 pub type Decl = Spanned<Decl_>;

src/libsyntax/ext/build.rs

@@ -538,7 +538,6 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             init: Some(ex),
             id: ast::DUMMY_NODE_ID,
             span: sp,
-            source: ast::LocalLet,
         });
         let decl = respan(sp, ast::DeclLocal(local));
         P(respan(sp, ast::StmtDecl(P(decl), ast::DUMMY_NODE_ID)))
@@ -562,7 +561,6 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             init: Some(ex),
             id: ast::DUMMY_NODE_ID,
             span: sp,
-            source: ast::LocalLet,
         });
         let decl = respan(sp, ast::DeclLocal(local));
         P(respan(sp, ast::StmtDecl(P(decl), ast::DUMMY_NODE_ID)))

src/libsyntax/ext/expand.rs

@@ -911,7 +911,7 @@ fn expand_non_macro_stmt(Spanned {node, span: stmt_span}: Stmt, fld: &mut MacroE
         StmtDecl(decl, node_id) => decl.and_then(|Spanned {node: decl, span}| match decl {
             DeclLocal(local) => {
                 // take it apart:
-                let rewritten_local = local.map(|Local {id, pat, ty, init, source, span}| {
+                let rewritten_local = local.map(|Local {id, pat, ty, init, span}| {
                     // expand the ty since TyFixedLengthVec contains an Expr
                     // and thus may have a macro use
                     let expanded_ty = ty.map(|t| fld.fold_ty(t));
@@ -941,7 +941,6 @@ fn expand_non_macro_stmt(Spanned {node, span: stmt_span}: Stmt, fld: &mut MacroE
                         pat: rewritten_pat,
                         // also, don't forget to expand the init:
                         init: init.map(|e| fld.fold_expr(e)),
-                        source: source,
                         span: span
                     }
                 });

src/libsyntax/fold.rs

@@ -515,12 +515,11 @@ pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesizedPara
 }
 
 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
-    l.map(|Local {id, pat, ty, init, source, span}| Local {
+    l.map(|Local {id, pat, ty, init, span}| Local {
         id: fld.new_id(id),
         ty: ty.map(|t| fld.fold_ty(t)),
         pat: fld.fold_pat(pat),
         init: init.map(|e| fld.fold_expr(e)),
-        source: source,
         span: fld.new_span(span)
     })
 }

src/libsyntax/parse/parser.rs

@@ -35,7 +35,7 @@ use ast::{ItemMac, ItemMod, ItemStruct, ItemTrait, ItemTy, ItemDefaultImpl};
 use ast::{ItemExternCrate, ItemUse};
 use ast::{LifetimeDef, Lit, Lit_};
 use ast::{LitBool, LitChar, LitByte, LitBinary};
-use ast::{LitStr, LitInt, Local, LocalLet};
+use ast::{LitStr, LitInt, Local};
 use ast::{MacStmtWithBraces, MacStmtWithSemicolon, MacStmtWithoutBraces};
 use ast::{MutImmutable, MutMutable, Mac_, MacInvocTT, MatchSource};
 use ast::{MutTy, BiMul, Mutability};
@@ -3432,7 +3432,6 @@ impl<'a> Parser<'a> {
             init: init,
             id: ast::DUMMY_NODE_ID,
             span: mk_sp(lo, self.last_span.hi),
-            source: LocalLet,
         }))
     }