From 51cbce17a332967527c5aabfd3fadbccb8a08ff1 Mon Sep 17 00:00:00 2001
From: Richard Barnes <rbarnes@meta.com>
Date: Wed, 16 Oct 2024 08:22:45 -0700
Subject: [PATCH] Fix shadowed variable in faiss/impl/simd_result_handlers.h

Summary:
Our upcoming compiler upgrade will require us not to have shadowed variables. Such variables have a _high_ bug rate and reduce readability, so we would like to avoid them even if the compiler was not forcing us to do so.

This codemod attempts to fix an instance of a shadowed variable. Please review with care: if it's failed the result will be a silent bug.

**What's a shadowed variable?**

Shadowed variables are variables in an inner scope with the same name as another variable in an outer scope. Having the same name for both variables might be semantically correct, but it can make the code confusing to read! It can also hide subtle bugs.

This diff fixes such an issue by renaming the variable.

 - If you approve of this diff, please use the "Accept & Ship" button :-)

Differential Revision: D64398709
---
 faiss/impl/simd_result_handlers.h | 32 +++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/faiss/impl/simd_result_handlers.h b/faiss/impl/simd_result_handlers.h
index eaf64c4b27..b8d89abc98 100644
--- a/faiss/impl/simd_result_handlers.h
+++ b/faiss/impl/simd_result_handlers.h
@@ -368,10 +368,10 @@ struct HeapHandler : ResultHandlerCompare<C, with_id_map> {
                 auto real_idx = this->adjust_id(b, j);
                 lt_mask -= 1 << j;
                 if (this->sel->is_member(real_idx)) {
-                    T dis = d32tab[j];
-                    if (C::cmp(heap_dis[0], dis)) {
+                    T dis_2 = d32tab[j];
+                    if (C::cmp(heap_dis[0], dis_2)) {
                         heap_replace_top<C>(
-                                k, heap_dis, heap_ids, dis, real_idx);
+                                k, heap_dis, heap_ids, dis_2, real_idx);
                     }
                 }
             }
@@ -380,10 +380,10 @@ struct HeapHandler : ResultHandlerCompare<C, with_id_map> {
                 // find first non-zero
                 int j = __builtin_ctz(lt_mask);
                 lt_mask -= 1 << j;
-                T dis = d32tab[j];
-                if (C::cmp(heap_dis[0], dis)) {
+                T dis_2 = d32tab[j];
+                if (C::cmp(heap_dis[0], dis_2)) {
                     int64_t idx = this->adjust_id(b, j);
-                    heap_replace_top<C>(k, heap_dis, heap_ids, dis, idx);
+                    heap_replace_top<C>(k, heap_dis, heap_ids, dis_2, idx);
                 }
             }
         }
@@ -480,8 +480,8 @@ struct ReservoirHandler : ResultHandlerCompare<C, with_id_map> {
                 auto real_idx = this->adjust_id(b, j);
                 lt_mask -= 1 << j;
                 if (this->sel->is_member(real_idx)) {
-                    T dis = d32tab[j];
-                    res.add(dis, real_idx);
+                    T dis_2 = d32tab[j];
+                    res.add(dis_2, real_idx);
                 }
             }
         } else {
@@ -489,8 +489,8 @@ struct ReservoirHandler : ResultHandlerCompare<C, with_id_map> {
                 // find first non-zero
                 int j = __builtin_ctz(lt_mask);
                 lt_mask -= 1 << j;
-                T dis = d32tab[j];
-                res.add(dis, this->adjust_id(b, j));
+                T dis_2 = d32tab[j];
+                res.add(dis_2, this->adjust_id(b, j));
             }
         }
     }
@@ -719,10 +719,10 @@ void dispatch_SIMDResultHandler_fixedCW(
         Types... args) {
     if (auto resh = dynamic_cast<SingleResultHandler<C, W>*>(&res)) {
         consumer.template f<SingleResultHandler<C, W>>(*resh, args...);
-    } else if (auto resh = dynamic_cast<HeapHandler<C, W>*>(&res)) {
-        consumer.template f<HeapHandler<C, W>>(*resh, args...);
-    } else if (auto resh = dynamic_cast<ReservoirHandler<C, W>*>(&res)) {
-        consumer.template f<ReservoirHandler<C, W>>(*resh, args...);
+    } else if (auto resh_2 = dynamic_cast<HeapHandler<C, W>*>(&res)) {
+        consumer.template f<HeapHandler<C, W>>(*resh_2, args...);
+    } else if (auto resh_2 = dynamic_cast<ReservoirHandler<C, W>*>(&res)) {
+        consumer.template f<ReservoirHandler<C, W>>(*resh_2, args...);
     } else { // generic handler -- will not be inlined
         FAISS_THROW_IF_NOT_FMT(
                 simd_result_handlers_accept_virtual,
@@ -752,8 +752,8 @@ void dispatch_SIMDResultHandler(
     if (res.sizeof_ids == 0) {
         if (auto resh = dynamic_cast<StoreResultHandler*>(&res)) {
             consumer.template f<StoreResultHandler>(*resh, args...);
-        } else if (auto resh = dynamic_cast<DummyResultHandler*>(&res)) {
-            consumer.template f<DummyResultHandler>(*resh, args...);
+        } else if (auto resh_2 = dynamic_cast<DummyResultHandler*>(&res)) {
+            consumer.template f<DummyResultHandler>(*resh_2, args...);
         } else { // generic path
             FAISS_THROW_IF_NOT_FMT(
                     simd_result_handlers_accept_virtual,