Auto merge of #4697 - Licenser:no-exit, r=flip1995

restriction lint for `std::process::exit`

Addition to #4655 - adds the lint checking for `std::process::exit`

changelog: add restriction lint for `std::process::exit`

clippy_lints/src/exit.rs

@@ -0,0 +1,47 @@
+use crate::utils::{is_entrypoint_fn, match_def_path, paths, qpath_res, span_lint};
+use if_chain::if_chain;
+use rustc::hir::{Expr, ExprKind, Item, ItemKind, Node};
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:** `exit()`  terminates the program and doesn't provide a
+    /// stack trace.
+    ///
+    /// **Why is this bad?** Ideally a program is terminated by finishing
+    /// the main function.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```ignore
+    /// std::process::exit(0)
+    /// ```
+    pub EXIT,
+    restriction,
+    "`std::process::exit` is called, terminating the program"
+}
+
+declare_lint_pass!(Exit => [EXIT]);
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Exit {
+    fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
+        if_chain! {
+            if let ExprKind::Call(ref path_expr, ref _args) = e.kind;
+            if let ExprKind::Path(ref path) = path_expr.kind;
+            if let Some(def_id) = qpath_res(cx, path, path_expr.hir_id).opt_def_id();
+            if match_def_path(cx, def_id, &paths::EXIT);
+            then {
+                let mut parent = cx.tcx.hir().get_parent_item(e.hir_id);
+                if let Some(Node::Item(Item{ident, kind: ItemKind::Fn(..), ..})) = cx.tcx.hir().find(parent) {
+                    // If the next item up is a function we check if it is an entry point
+                    // and only then emit a linter warning
+                    let def_id = cx.tcx.hir().local_def_id(parent);
+                    if !is_entrypoint_fn(cx, def_id) {
+                        span_lint(cx, EXIT, e.span, "usage of `process::exit`");
+                    }
+                }
+            }
+        }
+    }
+}

clippy_lints/src/lib.rs

@@ -188,6 +188,7 @@ pub mod escape;
 pub mod eta_reduction;
 pub mod eval_order_dependence;
 pub mod excessive_precision;
+pub mod exit;
 pub mod explicit_write;
 pub mod fallible_impl_from;
 pub mod format;
@@ -501,6 +502,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         &eval_order_dependence::DIVERGING_SUB_EXPRESSION,
         &eval_order_dependence::EVAL_ORDER_DEPENDENCE,
         &excessive_precision::EXCESSIVE_PRECISION,
+        &exit::EXIT,
         &explicit_write::EXPLICIT_WRITE,
         &fallible_impl_from::FALLIBLE_IMPL_FROM,
         &format::USELESS_FORMAT,
@@ -941,12 +943,14 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
     store.register_early_pass(move || box enum_variants::EnumVariantNames::new(enum_variant_name_threshold));
     store.register_late_pass(|| box unused_self::UnusedSelf);
     store.register_late_pass(|| box mutable_debug_assertion::DebugAssertWithMutCall);
+    store.register_late_pass(|| box exit::Exit);
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),
         LintId::of(&arithmetic::INTEGER_ARITHMETIC),
         LintId::of(&dbg_macro::DBG_MACRO),
         LintId::of(&else_if_without_else::ELSE_IF_WITHOUT_ELSE),
+        LintId::of(&exit::EXIT),
         LintId::of(&implicit_return::IMPLICIT_RETURN),
         LintId::of(&indexing_slicing::INDEXING_SLICING),
         LintId::of(&inherent_impl::MULTIPLE_INHERENT_IMPL),

clippy_lints/src/utils/paths.rs

@@ -27,6 +27,7 @@ pub const DROP: [&str; 3] = ["core", "mem", "drop"];
 pub const DROP_TRAIT: [&str; 4] = ["core", "ops", "drop", "Drop"];
 pub const DURATION: [&str; 3] = ["core", "time", "Duration"];
 pub const EARLY_CONTEXT: [&str; 4] = ["rustc", "lint", "context", "EarlyContext"];
+pub const EXIT: [&str; 3] = ["std", "process", "exit"];
 pub const FMT_ARGUMENTS_NEW_V1: [&str; 4] = ["core", "fmt", "Arguments", "new_v1"];
 pub const FMT_ARGUMENTS_NEW_V1_FORMATTED: [&str; 4] = ["core", "fmt", "Arguments", "new_v1_formatted"];
 pub const FMT_ARGUMENTV1_NEW: [&str; 4] = ["core", "fmt", "ArgumentV1", "new"];