[cleanup] Fix a bunch of -Wshadow

Bug: v8:12244,v8:12245
Change-Id: I49326278fa43cd07c17a01b70253303d2e861b06
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3291558Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78024}

src/compiler/persistent-map.h

@@ -490,13 +490,14 @@ PersistentMap<Key, Value, Hasher>::FindLeftmost(
     std::array<const FocusedTree*, kHashBits>* path) {
   const FocusedTree* current = start;
   while (*level < current->length) {
-    if (const FocusedTree* child = GetChild(current, *level, kLeft)) {
+    if (const FocusedTree* left_child = GetChild(current, *level, kLeft)) {
       (*path)[*level] = GetChild(current, *level, kRight);
-      current = child;
+      current = left_child;
       ++*level;
-    } else if (const FocusedTree* child = GetChild(current, *level, kRight)) {
+    } else if (const FocusedTree* right_child =
+                   GetChild(current, *level, kRight)) {
       (*path)[*level] = GetChild(current, *level, kLeft);
-      current = child;
+      current = right_child;
       ++*level;
     } else {
       UNREACHABLE();

src/libsampler/sampler.cc

@@ -210,8 +210,8 @@ void SamplerManager::AddSampler(Sampler* sampler) {
     sampler_map_.emplace(thread_id, std::move(samplers));
   } else {
     SamplerList& samplers = it->second;
-    auto it = std::find(samplers.begin(), samplers.end(), sampler);
-    if (it == samplers.end()) samplers.push_back(sampler);
+    auto sampler_it = std::find(samplers.begin(), samplers.end(), sampler);
+    if (sampler_it == samplers.end()) samplers.push_back(sampler);
   }
 }
 

src/objects/map.cc

@@ -1900,14 +1900,15 @@ Handle<Map> Map::TransitionToAccessorProperty(Isolate* isolate, Handle<Map> map,
   if (!maybe_transition.is_null()) {
     Handle<Map> transition(maybe_transition, isolate);
     DescriptorArray descriptors = transition->instance_descriptors(isolate);
-    InternalIndex descriptor = transition->LastAdded();
-    DCHECK(descriptors.GetKey(descriptor).Equals(*name));
+    InternalIndex last_descriptor = transition->LastAdded();
+    DCHECK(descriptors.GetKey(last_descriptor).Equals(*name));
 
     DCHECK_EQ(PropertyKind::kAccessor,
-              descriptors.GetDetails(descriptor).kind());
-    DCHECK_EQ(attributes, descriptors.GetDetails(descriptor).attributes());
+              descriptors.GetDetails(last_descriptor).kind());
+    DCHECK_EQ(attributes, descriptors.GetDetails(last_descriptor).attributes());
 
-    Handle<Object> maybe_pair(descriptors.GetStrongValue(descriptor), isolate);
+    Handle<Object> maybe_pair(descriptors.GetStrongValue(last_descriptor),
+                              isolate);
     if (!maybe_pair->IsAccessorPair()) {
       return Map::Normalize(isolate, map, mode,
                             "TransitionToAccessorFromNonPair");

src/objects/string.cc

@@ -417,7 +417,6 @@ bool String::SupportsExternalization() {
 const char* String::PrefixForDebugPrint() const {
   StringShape shape(*this);
   if (IsTwoByteRepresentation()) {
-    StringShape shape(*this);
     if (shape.IsInternalized()) {
       return "u#";
     } else if (shape.IsCons()) {
@@ -430,7 +429,6 @@ const char* String::PrefixForDebugPrint() const {
       return "u\"";
     }
   } else {
-    StringShape shape(*this);
     if (shape.IsInternalized()) {
       return "#";
     } else if (shape.IsCons()) {