From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../clippy_lints/src/if_then_some_else_none.rs     | 122 +++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs

(limited to 'src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs')

diff --git a/src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs b/src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs
new file mode 100644
index 000000000..b8d227855
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs
@@ -0,0 +1,122 @@
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::source::snippet_with_macro_callsite;
+use clippy_utils::{contains_return, higher, is_else_clause, is_lang_ctor, meets_msrv, msrvs, peel_blocks};
+use if_chain::if_chain;
+use rustc_hir::LangItem::{OptionNone, OptionSome};
+use rustc_hir::{Expr, ExprKind, Stmt, StmtKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for if-else that could be written to `bool::then`.
+    ///
+    /// ### Why is this bad?
+    /// Looks a little redundant. Using `bool::then` helps it have less lines of code.
+    ///
+    /// ### Example
+    /// ```rust
+    /// # let v = vec![0];
+    /// let a = if v.is_empty() {
+    ///     println!("true!");
+    ///     Some(42)
+    /// } else {
+    ///     None
+    /// };
+    /// ```
+    ///
+    /// Could be written:
+    ///
+    /// ```rust
+    /// # let v = vec![0];
+    /// let a = v.is_empty().then(|| {
+    ///     println!("true!");
+    ///     42
+    /// });
+    /// ```
+    #[clippy::version = "1.53.0"]
+    pub IF_THEN_SOME_ELSE_NONE,
+    restriction,
+    "Finds if-else that could be written using `bool::then`"
+}
+
+pub struct IfThenSomeElseNone {
+    msrv: Option<RustcVersion>,
+}
+
+impl IfThenSomeElseNone {
+    #[must_use]
+    pub fn new(msrv: Option<RustcVersion>) -> Self {
+        Self { msrv }
+    }
+}
+
+impl_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
+
+impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
+        if !meets_msrv(self.msrv, msrvs::BOOL_THEN) {
+            return;
+        }
+
+        if in_external_macro(cx.sess(), expr.span) {
+            return;
+        }
+
+        // We only care about the top-most `if` in the chain
+        if is_else_clause(cx.tcx, expr) {
+            return;
+        }
+
+        if_chain! {
+            if let Some(higher::If { cond, then, r#else: Some(els) }) = higher::If::hir(expr);
+            if let ExprKind::Block(then_block, _) = then.kind;
+            if let Some(then_expr) = then_block.expr;
+            if let ExprKind::Call(then_call, [then_arg]) = then_expr.kind;
+            if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
+            if is_lang_ctor(cx, then_call_qpath, OptionSome);
+            if let ExprKind::Path(ref qpath) = peel_blocks(els).kind;
+            if is_lang_ctor(cx, qpath, OptionNone);
+            if !stmts_contains_early_return(then_block.stmts);
+            then {
+                let cond_snip = snippet_with_macro_callsite(cx, cond.span, "[condition]");
+                let cond_snip = if matches!(cond.kind, ExprKind::Unary(_, _) | ExprKind::Binary(_, _, _)) {
+                    format!("({})", cond_snip)
+                } else {
+                    cond_snip.into_owned()
+                };
+                let arg_snip = snippet_with_macro_callsite(cx, then_arg.span, "");
+                let closure_body = if then_block.stmts.is_empty() {
+                    arg_snip.into_owned()
+                } else {
+                    format!("{{ /* snippet */ {} }}", arg_snip)
+                };
+                let help = format!(
+                    "consider using `bool::then` like: `{}.then(|| {})`",
+                    cond_snip,
+                    closure_body,
+                );
+                span_lint_and_help(
+                    cx,
+                    IF_THEN_SOME_ELSE_NONE,
+                    expr.span,
+                    "this could be simplified with `bool::then`",
+                    None,
+                    &help,
+                );
+            }
+        }
+    }
+
+    extract_msrv_attr!(LateContext);
+}
+
+fn stmts_contains_early_return(stmts: &[Stmt<'_>]) -> bool {
+    stmts.iter().any(|stmt| {
+        let Stmt { kind: StmtKind::Semi(e), .. } = stmt else { return false };
+
+        contains_return(e)
+    })
+}
-- 
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