Auto merge of #3772 - flip1995:ice-3719, r=Manishearth

Fix ICE #3719+#3718 in lint match_ref_pats

Fixes #3719
This conveniently also fixes #3718

The ICE occurs when the match expression was a macro call, where the macro was defined in another file. Since we don't have the ability to reproduce this behavior with our UI tests (AFAIK), I couldn't add a test reproducing this ICE.. However, I added a test which is related to the ICE, to show the new behavior of the lint.

I tested it with the mscheme repo locally and the ICE didn't happen anymore.

r? @matthiaskrgr

clippy_lints/src/matches.rs

@@ -570,13 +570,15 @@ fn check_match_ref_pats(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm], expr:
     if has_only_ref_pats(arms) {
         let mut suggs = Vec::new();
         let (title, msg) = if let ExprKind::AddrOf(Mutability::MutImmutable, ref inner) = ex.node {
-            suggs.push((ex.span, Sugg::hir(cx, inner, "..").to_string()));
+            let span = ex.span.source_callsite();
+            suggs.push((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));
             (
                 "you don't need to add `&` to both the expression and the patterns",
                 "try",
             )
         } else {
-            suggs.push((ex.span, Sugg::hir(cx, ex, "..").deref().to_string()));
+            let span = ex.span.source_callsite();
+            suggs.push((span, Sugg::hir_with_macro_callsite(cx, ex, "..").deref().to_string()));
             (
                 "you don't need to add `&` to all patterns",
                 "instead of prefixing all patterns with `&`, you can dereference the expression",

clippy_lints/src/utils/sugg.rs

@@ -1,7 +1,7 @@
 //! Contains utility functions to generate suggestions.
 #![deny(clippy::missing_docs_in_private_items)]
 
-use crate::utils::{higher, in_macro, snippet, snippet_opt};
+use crate::utils::{higher, in_macro, snippet, snippet_opt, snippet_with_macro_callsite};
 use matches::matches;
 use rustc::hir;
 use rustc::lint::{EarlyContext, LateContext, LintContext};
@@ -46,38 +46,7 @@ impl<'a> Sugg<'a> {
     pub fn hir_opt(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> Option<Self> {
         snippet_opt(cx, expr.span).map(|snippet| {
             let snippet = Cow::Owned(snippet);
-            match expr.node {
-                hir::ExprKind::AddrOf(..)
-                | hir::ExprKind::Box(..)
-                | hir::ExprKind::Closure(.., _)
-                | hir::ExprKind::If(..)
-                | hir::ExprKind::Unary(..)
-                | hir::ExprKind::Match(..) => Sugg::MaybeParen(snippet),
-                hir::ExprKind::Continue(..)
-                | hir::ExprKind::Yield(..)
-                | hir::ExprKind::Array(..)
-                | hir::ExprKind::Block(..)
-                | hir::ExprKind::Break(..)
-                | hir::ExprKind::Call(..)
-                | hir::ExprKind::Field(..)
-                | hir::ExprKind::Index(..)
-                | hir::ExprKind::InlineAsm(..)
-                | hir::ExprKind::Lit(..)
-                | hir::ExprKind::Loop(..)
-                | hir::ExprKind::MethodCall(..)
-                | hir::ExprKind::Path(..)
-                | hir::ExprKind::Repeat(..)
-                | hir::ExprKind::Ret(..)
-                | hir::ExprKind::Struct(..)
-                | hir::ExprKind::Tup(..)
-                | hir::ExprKind::While(..)
-                | hir::ExprKind::Err => Sugg::NonParen(snippet),
-                hir::ExprKind::Assign(..) => Sugg::BinOp(AssocOp::Assign, snippet),
-                hir::ExprKind::AssignOp(op, ..) => Sugg::BinOp(hirbinop2assignop(op), snippet),
-                hir::ExprKind::Binary(op, ..) => Sugg::BinOp(AssocOp::from_ast_binop(higher::binop(op.node)), snippet),
-                hir::ExprKind::Cast(..) => Sugg::BinOp(AssocOp::As, snippet),
-                hir::ExprKind::Type(..) => Sugg::BinOp(AssocOp::Colon, snippet),
-            }
+            Self::hir_from_snippet(expr, snippet)
         })
     }
 
@@ -111,6 +80,50 @@ impl<'a> Sugg<'a> {
         })
     }
 
+    /// Same as `hir`, but will use the pre expansion span if the `expr` was in a macro.
+    pub fn hir_with_macro_callsite(cx: &LateContext<'_, '_>, expr: &hir::Expr, default: &'a str) -> Self {
+        let snippet = snippet_with_macro_callsite(cx, expr.span, default);
+
+        Self::hir_from_snippet(expr, snippet)
+    }
+
+    /// Generate a suggestion for an expression with the given snippet. This is used by the `hir_*`
+    /// function variants of `Sugg`, since these use different snippet functions.
+    fn hir_from_snippet(expr: &hir::Expr, snippet: Cow<'a, str>) -> Self {
+        match expr.node {
+            hir::ExprKind::AddrOf(..)
+            | hir::ExprKind::Box(..)
+            | hir::ExprKind::Closure(.., _)
+            | hir::ExprKind::If(..)
+            | hir::ExprKind::Unary(..)
+            | hir::ExprKind::Match(..) => Sugg::MaybeParen(snippet),
+            hir::ExprKind::Continue(..)
+            | hir::ExprKind::Yield(..)
+            | hir::ExprKind::Array(..)
+            | hir::ExprKind::Block(..)
+            | hir::ExprKind::Break(..)
+            | hir::ExprKind::Call(..)
+            | hir::ExprKind::Field(..)
+            | hir::ExprKind::Index(..)
+            | hir::ExprKind::InlineAsm(..)
+            | hir::ExprKind::Lit(..)
+            | hir::ExprKind::Loop(..)
+            | hir::ExprKind::MethodCall(..)
+            | hir::ExprKind::Path(..)
+            | hir::ExprKind::Repeat(..)
+            | hir::ExprKind::Ret(..)
+            | hir::ExprKind::Struct(..)
+            | hir::ExprKind::Tup(..)
+            | hir::ExprKind::While(..)
+            | hir::ExprKind::Err => Sugg::NonParen(snippet),
+            hir::ExprKind::Assign(..) => Sugg::BinOp(AssocOp::Assign, snippet),
+            hir::ExprKind::AssignOp(op, ..) => Sugg::BinOp(hirbinop2assignop(op), snippet),
+            hir::ExprKind::Binary(op, ..) => Sugg::BinOp(AssocOp::from_ast_binop(higher::binop(op.node)), snippet),
+            hir::ExprKind::Cast(..) => Sugg::BinOp(AssocOp::As, snippet),
+            hir::ExprKind::Type(..) => Sugg::BinOp(AssocOp::Colon, snippet),
+        }
+    }
+
     /// Prepare a suggestion from an expression.
     pub fn ast(cx: &EarlyContext<'_>, expr: &ast::Expr, default: &'a str) -> Self {
         use syntax::ast::RangeLimits;

tests/ui/matches.rs

@@ -150,4 +150,29 @@ fn match_as_ref() {
     };
 }
 
-fn main() {}
+macro_rules! foo_variant(
+    ($idx:expr) => (Foo::get($idx).unwrap())
+);
+
+enum Foo {
+    A,
+    B,
+}
+
+impl Foo {
+    fn get(idx: u8) -> Option<&'static Self> {
+        match idx {
+            0 => Some(&Foo::A),
+            1 => Some(&Foo::B),
+            _ => None,
+        }
+    }
+}
+
+fn main() {
+    // ICE #3719
+    match foo_variant!(0) {
+        &Foo::A => println!("A"),
+        _ => println!("Wild"),
+    }
+}

tests/ui/matches.stderr

@@ -278,5 +278,19 @@ LL | |         Some(ref mut v) => Some(v),
 LL | |     };
    | |_____^ help: try this: `mut_owned.as_mut()`
 
-error: aborting due to 19 previous errors
+error: you don't need to add `&` to all patterns
+  --> $DIR/matches.rs:174:5
+   |
+LL | /     match foo_variant!(0) {
+LL | |         &Foo::A => println!("A"),
+LL | |         _ => println!("Wild"),
+LL | |     }
+   | |_____^
+help: instead of prefixing all patterns with `&`, you can dereference the expression
+   |
+LL |     match *foo_variant!(0) {
+LL |         Foo::A => println!("A"),
+   |
+
+error: aborting due to 20 previous errors