From 5461ed670eecedad74c82dd91ba532249d2073fb Mon Sep 17 00:00:00 2001
From: Jason Newcomb <jsnewcomb@pm.me>
Date: Sun, 16 Jan 2022 09:46:02 -0500
Subject: [PATCH] Don't lint `if_same_then_else` with `if let` conditions
---
clippy_lints/src/copies.rs | 29 +++++++++++++++++------------
tests/ui/if_same_then_else2.rs | 17 +++++++++++++++++
2 files changed, 34 insertions(+), 12 deletions(-)
diff --git a/clippy_lints/src/copies.rs b/clippy_lints/src/copies.rs
index 73ce656ad15..f44d370a8fd 100644
--- a/clippy_lints/src/copies.rs
+++ b/clippy_lints/src/copies.rs
@@ -183,7 +183,7 @@ impl<'tcx> LateLintPass<'tcx> for CopyAndPaste {
lint_same_cond(cx, &conds);
lint_same_fns_in_if_cond(cx, &conds);
// Block duplication
- lint_same_then_else(cx, &blocks, conds.len() == blocks.len(), expr);
+ lint_same_then_else(cx, &conds, &blocks, conds.len() == blocks.len(), expr);
}
}
}
@@ -192,6 +192,7 @@ impl<'tcx> LateLintPass<'tcx> for CopyAndPaste {
/// Implementation of `BRANCHES_SHARING_CODE` and `IF_SAME_THEN_ELSE` if the blocks are equal.
fn lint_same_then_else<'tcx>(
cx: &LateContext<'tcx>,
+ conds: &[&'tcx Expr<'_>],
blocks: &[&Block<'tcx>],
has_conditional_else: bool,
expr: &'tcx Expr<'_>,
@@ -204,7 +205,7 @@ fn lint_same_then_else<'tcx>(
// Check if each block has shared code
let has_expr = blocks[0].expr.is_some();
- let (start_eq, mut end_eq, expr_eq) = if let Some(block_eq) = scan_block_for_eq(cx, blocks) {
+ let (start_eq, mut end_eq, expr_eq) = if let Some(block_eq) = scan_block_for_eq(cx, conds, blocks) {
(block_eq.start_eq, block_eq.end_eq, block_eq.expr_eq)
} else {
return;
@@ -316,14 +317,14 @@ struct BlockEqual {
/// This function can also trigger the `IF_SAME_THEN_ELSE` in which case it'll return `None` to
/// abort any further processing and avoid duplicate lint triggers.
-fn scan_block_for_eq(cx: &LateContext<'_>, blocks: &[&Block<'_>]) -> Option<BlockEqual> {
+fn scan_block_for_eq(cx: &LateContext<'_>, conds: &[&Expr<'_>], blocks: &[&Block<'_>]) -> Option<BlockEqual> {
let mut start_eq = usize::MAX;
let mut end_eq = usize::MAX;
let mut expr_eq = true;
- let mut iter = blocks.windows(2);
- while let Some(&[win0, win1]) = iter.next() {
- let l_stmts = win0.stmts;
- let r_stmts = win1.stmts;
+ let mut iter = blocks.windows(2).enumerate();
+ while let Some((i, &[block0, block1])) = iter.next() {
+ let l_stmts = block0.stmts;
+ let r_stmts = block1.stmts;
// `SpanlessEq` now keeps track of the locals and is therefore context sensitive clippy#6752.
// The comparison therefore needs to be done in a way that builds the correct context.
@@ -340,22 +341,26 @@ fn scan_block_for_eq(cx: &LateContext<'_>, blocks: &[&Block<'_>]) -> Option<Bloc
it1.zip(it2)
.fold(0, |acc, (l, r)| if evaluator.eq_stmt(l, r) { acc + 1 } else { 0 })
};
- let block_expr_eq = both(&win0.expr, &win1.expr, |l, r| evaluator.eq_expr(l, r));
+ let block_expr_eq = both(&block0.expr, &block1.expr, |l, r| evaluator.eq_expr(l, r));
// IF_SAME_THEN_ELSE
if_chain! {
if block_expr_eq;
if l_stmts.len() == r_stmts.len();
if l_stmts.len() == current_start_eq;
- if !is_lint_allowed(cx, IF_SAME_THEN_ELSE, win0.hir_id);
- if !is_lint_allowed(cx, IF_SAME_THEN_ELSE, win1.hir_id);
+ // `conds` may have one last item than `blocks`.
+ // Any `i` from `blocks.windows(2)` will exist in `conds`, but `i+1` may not exist on the last iteration.
+ if !matches!(conds[i].kind, ExprKind::Let(..));
+ if !matches!(conds.get(i + 1).map(|e| &e.kind), Some(ExprKind::Let(..)));
+ if !is_lint_allowed(cx, IF_SAME_THEN_ELSE, block0.hir_id);
+ if !is_lint_allowed(cx, IF_SAME_THEN_ELSE, block1.hir_id);
then {
span_lint_and_note(
cx,
IF_SAME_THEN_ELSE,
- win0.span,
+ block0.span,
"this `if` has identical blocks",
- Some(win1.span),
+ Some(block1.span),
"same as this",
);
diff --git a/tests/ui/if_same_then_else2.rs b/tests/ui/if_same_then_else2.rs
index 69189d9e0c0..0016009a02f 100644
--- a/tests/ui/if_same_then_else2.rs
+++ b/tests/ui/if_same_then_else2.rs
@@ -138,6 +138,23 @@ fn if_same_then_else2() -> Result<&'static str, ()> {
let (y, x) = (1, 2);
return Ok(&foo[x..y]);
}
+
+ // Issue #7579
+ let _ = if let Some(0) = None { 0 } else { 0 };
+
+ if true {
+ return Err(());
+ } else if let Some(0) = None {
+ return Err(());
+ }
+
+ let _ = if let Some(0) = None {
+ 0
+ } else if let Some(1) = None {
+ 0
+ } else {
+ 0
+ };
}
fn main() {}