Auto merge of #10953 - KisaragiEffective:missing_panics_doc_trigger_on_expect, r=dswij

[`missing_panics_doc`]: pickup expect method

close #10240

*Please write a short comment explaining your change (or "none" for internal only changes)*

changelog: [`missing_panics_doc`]: pickup expect method

6 files changed, 115 insertions, 3 deletions

diff --git a/clippy_dev/src/fmt.rs b/clippy_dev/src/fmt.rs
index 25623144181..ee559d45dd1 100644
--- a/clippy_dev/src/fmt.rs
+++ b/clippy_dev/src/fmt.rs
@@ -35,6 +35,7 @@ struct FmtContext {
 }
 
 // the "main" function of cargo dev fmt
+#[allow(clippy::missing_panics_doc)]
 pub fn run(check: bool, verbose: bool) {
     fn try_run(context: &FmtContext) -> Result<bool, CliError> {
         let mut success = true;
diff --git a/clippy_dev/src/lib.rs b/clippy_dev/src/lib.rs
index 56a269288c0..8aaa029f776 100644
--- a/clippy_dev/src/lib.rs
+++ b/clippy_dev/src/lib.rs
@@ -29,6 +29,10 @@ static CARGO_CLIPPY_EXE: &str = "cargo-clippy";
 static CARGO_CLIPPY_EXE: &str = "cargo-clippy.exe";
 
 /// Returns the path to the `cargo-clippy` binary
+///
+/// # Panics
+///
+/// Panics if the path of current executable could not be retrieved.
 #[must_use]
 pub fn cargo_clippy_path() -> PathBuf {
     let mut path = std::env::current_exe().expect("failed to get current executable name");
@@ -61,6 +65,8 @@ pub fn clippy_project_root() -> PathBuf {
     panic!("error: Can't determine root of project. Please run inside a Clippy working dir.");
 }
 
+/// # Panics
+/// Panics if given command result was failed.
 pub fn exit_if_err(status: io::Result<ExitStatus>) {
     match status.expect("failed to run command").code() {
         Some(0) => {},
diff --git a/clippy_dev/src/new_lint.rs b/clippy_dev/src/new_lint.rs
index f970a32726b..f0ccdb0fe10 100644
--- a/clippy_dev/src/new_lint.rs
+++ b/clippy_dev/src/new_lint.rs
@@ -36,6 +36,7 @@ impl<T> Context for io::Result<T> {
 /// # Errors
 ///
 /// This function errors out if the files couldn't be created or written to.
+#[allow(clippy::missing_panics_doc)]
 pub fn create(
     pass: &String,
     lint_name: Option<&String>,
diff --git a/clippy_lints/src/doc.rs b/clippy_lints/src/doc.rs
index 0617c3ea5e9..815495a7b7a 100644
--- a/clippy_lints/src/doc.rs
+++ b/clippy_lints/src/doc.rs
@@ -916,8 +916,8 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
             }
         }
 
-        // check for `unwrap`
-        if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
+        // check for `unwrap` and `expect` for both `Option` and `Result`
+        if let Some(arglists) = method_chain_args(expr, &["unwrap"]).or(method_chain_args(expr, &["expect"])) {
             let receiver_ty = self.typeck_results.expr_ty(arglists[0].0).peel_refs();
             if is_type_diagnostic_item(self.cx, receiver_ty, sym::Option)
                 || is_type_diagnostic_item(self.cx, receiver_ty, sym::Result)
diff --git a/tests/ui/missing_panics_doc.rs b/tests/ui/missing_panics_doc.rs
index 10aa436d6cd..d544a0b1afb 100644
--- a/tests/ui/missing_panics_doc.rs
+++ b/tests/ui/missing_panics_doc.rs
@@ -151,3 +151,35 @@ pub fn debug_assertions() {
     debug_assert_eq!(1, 2);
     debug_assert_ne!(1, 2);
 }
+
+// all function must be triggered the lint.
+// `pub` is required, because the lint does not consider unreachable items
+pub mod issue10240 {
+    pub fn option_unwrap<T>(v: &[T]) -> &T {
+        let o: Option<&T> = v.last();
+        o.unwrap()
+    }
+
+    pub fn option_expect<T>(v: &[T]) -> &T {
+        let o: Option<&T> = v.last();
+        o.expect("passed an empty thing")
+    }
+
+    pub fn result_unwrap<T>(v: &[T]) -> &T {
+        let res: Result<&T, &str> = v.last().ok_or("oh noes");
+        res.unwrap()
+    }
+
+    pub fn result_expect<T>(v: &[T]) -> &T {
+        let res: Result<&T, &str> = v.last().ok_or("oh noes");
+        res.expect("passed an empty thing")
+    }
+
+    pub fn last_unwrap(v: &[u32]) -> u32 {
+        *v.last().unwrap()
+    }
+
+    pub fn last_expect(v: &[u32]) -> u32 {
+        *v.last().expect("passed an empty thing")
+    }
+}
diff --git a/tests/ui/missing_panics_doc.stderr b/tests/ui/missing_panics_doc.stderr
index 183c262ce0b..39d97f08373 100644
--- a/tests/ui/missing_panics_doc.stderr
+++ b/tests/ui/missing_panics_doc.stderr
@@ -83,5 +83,77 @@ note: first possible panic found here
 LL |     assert_ne!(x, 0);
    |     ^^^^^^^^^^^^^^^^
 
-error: aborting due to 7 previous errors
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:158:5
+   |
+LL |     pub fn option_unwrap<T>(v: &[T]) -> &T {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:160:9
+   |
+LL |         o.unwrap()
+   |         ^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:163:5
+   |
+LL |     pub fn option_expect<T>(v: &[T]) -> &T {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:165:9
+   |
+LL |         o.expect("passed an empty thing")
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:168:5
+   |
+LL |     pub fn result_unwrap<T>(v: &[T]) -> &T {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:170:9
+   |
+LL |         res.unwrap()
+   |         ^^^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:173:5
+   |
+LL |     pub fn result_expect<T>(v: &[T]) -> &T {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:175:9
+   |
+LL |         res.expect("passed an empty thing")
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:178:5
+   |
+LL |     pub fn last_unwrap(v: &[u32]) -> u32 {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:179:10
+   |
+LL |         *v.last().unwrap()
+   |          ^^^^^^^^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/missing_panics_doc.rs:182:5
+   |
+LL |     pub fn last_expect(v: &[u32]) -> u32 {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/missing_panics_doc.rs:183:10
+   |
+LL |         *v.last().expect("passed an empty thing")
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 13 previous errors