Fix if_then_panic for #![no_std] and Rust 2021

clippy_lints/src/if_then_panic.rs

@@ -54,16 +54,23 @@ impl LateLintPass<'_> for IfThenPanic {
             if !cx.tcx.sess.source_map().is_multiline(cond.span);
 
             then {
-                let span = if let Some(panic_expn) = PanicExpn::parse(semi) {
+                let call = if_chain! {
+                    if let ExprKind::Block(block, _) = semi.kind;
+                    if let Some(init) = block.expr;
+                    then {
+                        init
+                    } else {
+                        semi
+                    }
+                };
+                let span = if let Some(panic_expn) = PanicExpn::parse(call) {
                     match *panic_expn.format_args.value_args {
                         [] => panic_expn.format_args.format_string_span,
                         [.., last] => panic_expn.format_args.format_string_span.to(last.span),
                     }
                 } else {
                     if_chain! {
-                        if let ExprKind::Block(block, _) = semi.kind;
-                        if let Some(init) = block.expr;
-                        if let ExprKind::Call(_, [format_args]) = init.kind;
+                        if let ExprKind::Call(_, [format_args]) = call.kind;
 
                         then {
                             format_args.span

clippy_lints/src/matches.rs

@@ -968,8 +968,7 @@ fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm
                     }
                     if_chain! {
                         if matching_wild;
-                        if let ExprKind::Block(block, _) = arm.body.kind;
-                        if is_panic_block(block);
+                        if is_panic_call(arm.body);
                         then {
                             // `Err(_)` or `Err(_e)` arm with `panic!` found
                             span_lint_and_note(cx,
@@ -1172,14 +1171,19 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
 }
 
 // If the block contains only a `panic!` macro (as expression or statement)
-fn is_panic_block(block: &Block<'_>) -> bool {
-    match (&block.expr, block.stmts.len(), block.stmts.first()) {
-        (&Some(exp), 0, _) => is_expn_of(exp.span, "panic").is_some() && is_expn_of(exp.span, "unreachable").is_none(),
-        (&None, 1, Some(stmt)) => {
-            is_expn_of(stmt.span, "panic").is_some() && is_expn_of(stmt.span, "unreachable").is_none()
-        },
-        _ => false,
-    }
+fn is_panic_call(expr: &Expr<'_>) -> bool {
+    // Unwrap any wrapping blocks
+    let span = if let ExprKind::Block(block, _) = expr.kind {
+        match (&block.expr, block.stmts.len(), block.stmts.first()) {
+            (&Some(exp), 0, _) => exp.span,
+            (&None, 1, Some(stmt)) => stmt.span,
+            _ => return false,
+        }
+    } else {
+        expr.span
+    };
+
+    is_expn_of(span, "panic").is_some() && is_expn_of(span, "unreachable").is_none()
 }
 
 fn check_match_ref_pats<'a, 'b, I>(cx: &LateContext<'_>, ex: &Expr<'_>, pats: I, expr: &Expr<'_>)

clippy_utils/src/higher.rs

@@ -718,9 +718,7 @@ impl PanicExpn<'tcx> {
     /// Parses an expanded `panic!` invocation
     pub fn parse(expr: &'tcx Expr<'tcx>) -> Option<Self> {
         if_chain! {
-            if let ExprKind::Block(block, _) = expr.kind;
-            if let Some(init) = block.expr;
-            if let ExprKind::Call(_, [format_args]) = init.kind;
+            if let ExprKind::Call(_, [format_args]) = expr.kind;
             let expn_data = expr.span.ctxt().outer_expn_data();
             if let ExprKind::AddrOf(_, _, format_args) = format_args.kind;
             if let Some(format_args) = FormatArgsExpn::parse(format_args);

tests/ui/if_then_panic_core.fixed

@@ -0,0 +1,42 @@
+// run-rustfix
+#![crate_type = "lib"]
+#![no_std]
+#![warn(clippy::if_then_panic)]
+
+pub fn main() {
+    let a = &[1, 2, 3];
+    let c = Some(2);
+    if !a.is_empty()
+        && a.len() == 3
+        && c != None
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+    {
+        panic!("qaqaq{:?}", a);
+    }
+    assert!(a.is_empty(), "qaqaq{:?}", a);
+    assert!(a.is_empty(), "qwqwq");
+    if a.len() == 3 {
+        format_args!("qwq");
+        format_args!("qwq");
+        format_args!("qwq");
+    }
+    if let Some(b) = c {
+        panic!("orz {}", b);
+    }
+    if a.len() == 3 {
+        panic!("qaqaq");
+    } else {
+        format_args!("qwq");
+    }
+    let b = &[1, 2, 3];
+    assert!(!b.is_empty(), "panic1");
+    assert!(!(b.is_empty() && a.is_empty()), "panic2");
+    assert!(!(a.is_empty() && !b.is_empty()), "panic3");
+    assert!(!(b.is_empty() || a.is_empty()), "panic4");
+    assert!(!(a.is_empty() || !b.is_empty()), "panic5");
+}

tests/ui/if_then_panic_core.rs

@@ -0,0 +1,56 @@
+// run-rustfix
+#![crate_type = "lib"]
+#![no_std]
+#![warn(clippy::if_then_panic)]
+
+pub fn main() {
+    let a = &[1, 2, 3];
+    let c = Some(2);
+    if !a.is_empty()
+        && a.len() == 3
+        && c != None
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+    {
+        panic!("qaqaq{:?}", a);
+    }
+    if !a.is_empty() {
+        panic!("qaqaq{:?}", a);
+    }
+    if !a.is_empty() {
+        panic!("qwqwq");
+    }
+    if a.len() == 3 {
+        format_args!("qwq");
+        format_args!("qwq");
+        format_args!("qwq");
+    }
+    if let Some(b) = c {
+        panic!("orz {}", b);
+    }
+    if a.len() == 3 {
+        panic!("qaqaq");
+    } else {
+        format_args!("qwq");
+    }
+    let b = &[1, 2, 3];
+    if b.is_empty() {
+        panic!("panic1");
+    }
+    if b.is_empty() && a.is_empty() {
+        panic!("panic2");
+    }
+    if a.is_empty() && !b.is_empty() {
+        panic!("panic3");
+    }
+    if b.is_empty() || a.is_empty() {
+        panic!("panic4");
+    }
+    if a.is_empty() || !b.is_empty() {
+        panic!("panic5");
+    }
+}

tests/ui/if_then_panic_core.stderr

@@ -0,0 +1,60 @@
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:21:5
+   |
+LL | /     if !a.is_empty() {
+LL | |         panic!("qaqaq{:?}", a);
+LL | |     }
+   | |_____^ help: try: `assert!(a.is_empty(), "qaqaq{:?}", a);`
+   |
+   = note: `-D clippy::if-then-panic` implied by `-D warnings`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:24:5
+   |
+LL | /     if !a.is_empty() {
+LL | |         panic!("qwqwq");
+LL | |     }
+   | |_____^ help: try: `assert!(a.is_empty(), "qwqwq");`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:41:5
+   |
+LL | /     if b.is_empty() {
+LL | |         panic!("panic1");
+LL | |     }
+   | |_____^ help: try: `assert!(!b.is_empty(), "panic1");`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:44:5
+   |
+LL | /     if b.is_empty() && a.is_empty() {
+LL | |         panic!("panic2");
+LL | |     }
+   | |_____^ help: try: `assert!(!(b.is_empty() && a.is_empty()), "panic2");`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:47:5
+   |
+LL | /     if a.is_empty() && !b.is_empty() {
+LL | |         panic!("panic3");
+LL | |     }
+   | |_____^ help: try: `assert!(!(a.is_empty() && !b.is_empty()), "panic3");`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:50:5
+   |
+LL | /     if b.is_empty() || a.is_empty() {
+LL | |         panic!("panic4");
+LL | |     }
+   | |_____^ help: try: `assert!(!(b.is_empty() || a.is_empty()), "panic4");`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic_core.rs:53:5
+   |
+LL | /     if a.is_empty() || !b.is_empty() {
+LL | |         panic!("panic5");
+LL | |     }
+   | |_____^ help: try: `assert!(!(a.is_empty() || !b.is_empty()), "panic5");`
+
+error: aborting due to 7 previous errors
+

tests/ui/match_wild_err_arm_core.rs

@@ -0,0 +1,67 @@
+#![crate_type = "lib"]
+#![no_std]
+#![feature(exclusive_range_pattern)]
+#![allow(clippy::match_same_arms)]
+#![warn(clippy::match_wild_err_arm)]
+
+fn foo() {}
+
+fn match_wild_err_arm() {
+    let x: Result<i32, &str> = Ok(3);
+
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => panic!("err"),
+    }
+
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => panic!(),
+    }
+
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => {
+            panic!();
+        },
+    }
+
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_e) => panic!(),
+    }
+
+    // Allowed when used in `panic!`.
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_e) => panic!("{}", _e),
+    }
+
+    // Allowed when not with `panic!` block.
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => foo(),
+    }
+
+    // Allowed when used with `unreachable!`.
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => unreachable!(),
+    }
+
+    // Allowed when used with `unreachable!`.
+    match x {
+        Ok(3) => (),
+        Ok(_) => (),
+        Err(_) => {
+            unreachable!();
+        },
+    }
+}

tests/ui/match_wild_err_arm_core.stderr

@@ -0,0 +1,35 @@
+error: `Err(_)` matches all errors
+  --> $DIR/match_wild_err_arm_core.rs:15:9
+   |
+LL |         Err(_) => panic!("err"),
+   |         ^^^^^^
+   |
+   = note: `-D clippy::match-wild-err-arm` implied by `-D warnings`
+   = note: match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable
+
+error: `Err(_)` matches all errors
+  --> $DIR/match_wild_err_arm_core.rs:21:9
+   |
+LL |         Err(_) => panic!(),
+   |         ^^^^^^
+   |
+   = note: match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable
+
+error: `Err(_)` matches all errors
+  --> $DIR/match_wild_err_arm_core.rs:27:9
+   |
+LL |         Err(_) => {
+   |         ^^^^^^
+   |
+   = note: match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable
+
+error: `Err(_e)` matches all errors
+  --> $DIR/match_wild_err_arm_core.rs:35:9
+   |
+LL |         Err(_e) => panic!(),
+   |         ^^^^^^^
+   |
+   = note: match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable
+
+error: aborting due to 4 previous errors
+