check expr using a loop

rust-lang · Apr 21, 2021 · 56bb890 · 56bb890
1 parent 350b117
commit 56bb890
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Showing 3 changed files with 65 additions and 16 deletions.
diff --git a/clippy_lints/src/unused_io_amount.rs b/clippy_lints/src/unused_io_amount.rs
@@ -47,24 +47,15 @@ impl<'tcx> LateLintPass<'tcx> for UnusedIoAmount {
                         func.kind,
                         hir::ExprKind::Path(hir::QPath::LangItem(hir::LangItem::TryIntoResult, _))
                     ) {
-                        match args[0].kind {
-                            hir::ExprKind::MethodCall(ref path, _, ref args, _) => {
-                                if matches!(&*path.ident.as_str(), "or" | "or_else" | "ok") {
-                                    check_method_call(cx, &args[0], expr);
-                                }
-                            },
-                            _ => {
-                                check_method_call(cx, &args[0], expr);
-                            },
-                        }
+                        check_map_error(cx, &args[0], expr);
                     }
                 } else {
-                    check_method_call(cx, res, expr);
+                    check_map_error(cx, res, expr);
                 }
             },
             hir::ExprKind::MethodCall(path, _, args, _) => match &*path.ident.as_str() {
                 "expect" | "unwrap" | "unwrap_or" | "unwrap_or_else" => {
-                    check_method_call(cx, &args[0], expr);
+                    check_map_error(cx, &args[0], expr);
                 },
                 _ => (),
             },
@@ -73,6 +64,18 @@ impl<'tcx> LateLintPass<'tcx> for UnusedIoAmount {
     }
 }
 
+fn check_map_error(cx: &LateContext<'_>, call: &hir::Expr<'_>, expr: &hir::Expr<'_>) {
+    let mut call = call;
+    while let hir::ExprKind::MethodCall(ref path, _, ref args, _) = call.kind {
+        if matches!(&*path.ident.as_str(), "or" | "or_else" | "ok") {
+            call = &args[0];
+        } else {
+            break;
+        }
+    }
+    check_method_call(cx, call, expr);
+}
+
 fn check_method_call(cx: &LateContext<'_>, call: &hir::Expr<'_>, expr: &hir::Expr<'_>) {
     if let hir::ExprKind::MethodCall(path, _, _, _) = call.kind {
         let symbol = &*path.ident.as_str();

diff --git a/tests/ui/unused_io_amount.rs b/tests/ui/unused_io_amount.rs
@@ -38,6 +38,7 @@ fn or_else(file: &str) -> io::Result<()> {
     Ok(())
 }
 
+#[derive(Debug)]
 enum Error {
     Kind,
 }
@@ -49,4 +50,15 @@ fn or(file: &str) -> Result<(), Error> {
     Ok(())
 }
 
+fn combine_or(file: &str) -> Result<(), Error> {
+    let mut reader = std::fs::File::open(file).unwrap();
+    let mut result = [0u8; 0];
+    reader
+        .read(&mut result)
+        .or(Err(Error::Kind))
+        .or(Err(Error::Kind))
+        .expect("error");
+    Ok(())
+}
+
 fn main() {}
diff --git a/tests/ui/unused_io_amount.stderr b/tests/ui/unused_io_amount.stderr
@@ -1,17 +1,41 @@
+error: written amount is not handled. Use `Write::write_all` instead
+  --> $DIR/unused_io_amount.rs:7:5
+   |
+LL |     s.write(b"test")?;
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::unused-io-amount` implied by `-D warnings`
+
+error: read amount is not handled. Use `Read::read_exact` instead
+  --> $DIR/unused_io_amount.rs:9:5
+   |
+LL |     s.read(&mut buf)?;
+   |     ^^^^^^^^^^^^^^^^^
+
 error: written amount is not handled. Use `Write::write_all` instead
   --> $DIR/unused_io_amount.rs:14:5
    |
 LL |     s.write(b"test").unwrap();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::unused-io-amount` implied by `-D warnings`
 
 error: read amount is not handled. Use `Read::read_exact` instead
   --> $DIR/unused_io_amount.rs:16:5
    |
 LL |     s.read(&mut buf).unwrap();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: read amount is not handled
+  --> $DIR/unused_io_amount.rs:20:5
+   |
+LL |     s.read_vectored(&mut [io::IoSliceMut::new(&mut [])])?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: written amount is not handled
+  --> $DIR/unused_io_amount.rs:21:5
+   |
+LL |     s.write_vectored(&[io::IoSlice::new(&[])])?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: read amount is not handled. Use `Read::read_exact` instead
   --> $DIR/unused_io_amount.rs:28:5
    |
@@ -25,10 +49,20 @@ LL |     reader.read(&mut result).or_else(|err| Err(err))?;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: read amount is not handled. Use `Read::read_exact` instead
-  --> $DIR/unused_io_amount.rs:48:5
+  --> $DIR/unused_io_amount.rs:49:5
    |
 LL |     reader.read(&mut result).or(Err(Error::Kind))?;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 5 previous errors
+error: read amount is not handled. Use `Read::read_exact` instead
+  --> $DIR/unused_io_amount.rs:56:5
+   |
+LL | /     reader
+LL | |         .read(&mut result)
+LL | |         .or(Err(Error::Kind))
+LL | |         .or(Err(Error::Kind))
+LL | |         .expect("error");
+   | |________________________^
+
+error: aborting due to 10 previous errors