Switch `zip` to `zip_equal` where possible (#6389)

There are two uses I'm not converting here, that seem to want the
"shortest" behavior. For everything else, I'm going to `zip_equal` since
it's more restrictive.

I wish `zip` were named `zip_shortest`.

common/command_line.h

@@ -813,7 +813,7 @@ auto OneOfArgBuilder::OneOfImpl(const OneOfValueT<U> (&input_values)[N],
   new (&arg()->value_action) Arg::ValueActionT(
       [values, match](const Arg& arg, llvm::StringRef value_string) -> bool {
         for (auto [value, arg_value_string] :
-             llvm::zip(values, arg.value_strings)) {
+             llvm::zip_equal(values, arg.value_strings)) {
           if (value_string == arg_value_string) {
             match(value);
             return true;

toolchain/check/eval.cpp

@@ -1720,9 +1720,9 @@ static auto MakeConstantForBuiltinCall(EvalContext& eval_context,
       CARBON_CHECK(arg_ids.size() == 2);
       auto lhs_facet_type_id = SemIR::FacetTypeId::None;
       auto rhs_facet_type_id = SemIR::FacetTypeId::None;
-      for (auto [facet_type_id, type_arg_id] :
-           llvm::zip(std::to_array({&lhs_facet_type_id, &rhs_facet_type_id}),
-                     context.types().GetBlockAsTypeInstIds(arg_ids))) {
+      for (auto [facet_type_id, type_arg_id] : llvm::zip_equal(
+               std::to_array({&lhs_facet_type_id, &rhs_facet_type_id}),
+               context.types().GetBlockAsTypeInstIds(arg_ids))) {
         if (auto facet_type =
                 context.insts().TryGetAs<SemIR::FacetType>(type_arg_id)) {
           *facet_type_id = facet_type->facet_type_id;

toolchain/check/handle_struct.cpp

@@ -82,7 +82,8 @@ static auto DiagnoseDuplicateNames(
     llvm::ArrayRef<SemIR::StructTypeField> fields, bool is_struct_type_literal)
     -> bool {
   Map<SemIR::NameId, Parse::NodeId> names;
-  for (auto [field_name_node, field] : llvm::zip(field_name_nodes, fields)) {
+  for (auto [field_name_node, field] :
+       llvm::zip_equal(field_name_nodes, fields)) {
     auto result = names.Insert(field.name_id, field_name_node);
     if (!result.is_inserted()) {
       CARBON_DIAGNOSTIC(StructNameDuplicate, Error,

toolchain/check/impl.cpp

@@ -137,7 +137,7 @@ auto ImplWitnessStartDefinition(Context& context, SemIR::Impl& impl) -> void {
   // Check we have a value for all non-function associated constants in the
   // witness.
   for (auto [assoc_entity, witness_value] :
-       llvm::zip(assoc_entities, witness_block)) {
+       llvm::zip_equal(assoc_entities, witness_block)) {
     auto decl_id = context.constant_values().GetConstantInstId(assoc_entity);
     CARBON_CHECK(decl_id.has_value(), "Non-constant associated entity");
     if (auto decl =
@@ -187,7 +187,7 @@ auto FinishImplWitness(Context& context, SemIR::ImplId impl_id) -> void {
   llvm::SmallVector<SemIR::InstId> used_decl_ids;
 
   for (auto [assoc_entity, witness_value] :
-       llvm::zip(assoc_entities, witness_block)) {
+       llvm::zip_equal(assoc_entities, witness_block)) {
     auto decl_id =
         context.constant_values().GetInstId(SemIR::GetConstantValueInSpecific(
             context.sem_ir(), impl.interface.specific_id, assoc_entity));

toolchain/check/impl_lookup.cpp

@@ -459,7 +459,7 @@ class SubstWitnessesCallbacks : public SubstInstCallbacks {
     auto lookup_query_interface =
         context().specific_interfaces().Get(specific_interface_id);
     for (auto [interface, witness_inst_id] :
-         llvm::zip(interfaces_, witness_inst_ids_)) {
+         llvm::zip_equal(interfaces_, witness_inst_ids_)) {
       // If the `LookupImplWitness` for `.Self` is not looking for the same
       // interface as we have a witness for, this is not the right witness to
       // use to replace the lookup for `.Self`.

toolchain/check/import_ref.cpp

@@ -2157,7 +2157,7 @@ static auto TryResolveTypedInst(ImportRefResolver& resolver,
   }
 
   for (auto [import_vtable_entry_inst_id, local_vtable_entry_inst_id] :
-       llvm::zip(virtual_functions, lazy_virtual_functions)) {
+       llvm::zip_equal(virtual_functions, lazy_virtual_functions)) {
     // Use LoadedImportRef for imported symbolic constant vtable entries so they
     // can carry attached constants necessary for applying specifics to these
     // constants when they are used.
@@ -3211,7 +3211,7 @@ static auto TryResolveTypedInst(ImportRefResolver& resolver,
   llvm::SmallVector<SemIR::StructTypeField> new_fields;
   new_fields.reserve(orig_fields.size());
   for (auto [orig_field, field_type_inst_id] :
-       llvm::zip(orig_fields, field_type_inst_ids)) {
+       llvm::zip_equal(orig_fields, field_type_inst_ids)) {
     auto name_id = GetLocalNameId(resolver, orig_field.name_id);
     new_fields.push_back(
         {.name_id = name_id, .type_inst_id = field_type_inst_id});
@@ -3909,8 +3909,8 @@ static auto ResolveLocalEvalBlock(ImportRefResolver& resolver,
   // Set the locations of the instructions in the inst block to match those of
   // the imported instructions.
   for (auto [import_inst_id, local_inst_id] :
-       llvm::zip(resolver.import_inst_blocks().Get(import_block_id),
-                 resolver.local_inst_blocks().Get(eval_block_id))) {
+       llvm::zip_equal(resolver.import_inst_blocks().Get(import_block_id),
+                       resolver.local_inst_blocks().Get(eval_block_id))) {
     auto import_ir_inst_id = AddImportIRInst(resolver, import_inst_id);
     resolver.local_insts().SetLocId(local_inst_id, import_ir_inst_id);
   }

toolchain/check/pattern_match.cpp

@@ -527,7 +527,7 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
   auto add_all_subscrutinees =
       [&](llvm::ArrayRef<SemIR::InstId> subscrutinee_ids) {
         for (auto [subpattern_id, subscrutinee_id] :
-             llvm::reverse(llvm::zip(subpattern_ids, subscrutinee_ids))) {
+             llvm::reverse(llvm::zip_equal(subpattern_ids, subscrutinee_ids))) {
           AddWork(
               {.pattern_id = subpattern_id, .scrutinee_id = subscrutinee_id});
         }

toolchain/check/subst.cpp

@@ -252,9 +252,10 @@ static auto PopOperand(Context& context, Worklist& worklist,
       new_facet_type_info.self_impls_named_constraints.resize(
           old_facet_type_info.self_impls_named_constraints.size(),
           SemIR::SpecificNamedConstraint::None);
-      for (auto [old_constraint, new_constraint] : llvm::reverse(
-               llvm::zip(old_facet_type_info.self_impls_named_constraints,
-                         new_facet_type_info.self_impls_named_constraints))) {
+      for (auto [old_constraint, new_constraint] :
+           llvm::reverse(llvm::zip_equal(
+               old_facet_type_info.self_impls_named_constraints,
+               new_facet_type_info.self_impls_named_constraints))) {
         new_constraint = {
             .named_constraint_id = old_constraint.named_constraint_id,
             .specific_id = pop_specific(old_constraint.specific_id)};
@@ -263,8 +264,8 @@ static auto PopOperand(Context& context, Worklist& worklist,
           old_facet_type_info.extend_named_constraints.size(),
           SemIR::SpecificNamedConstraint::None);
       for (auto [old_constraint, new_constraint] : llvm::reverse(
-               llvm::zip(old_facet_type_info.extend_named_constraints,
-                         new_facet_type_info.extend_named_constraints))) {
+               llvm::zip_equal(old_facet_type_info.extend_named_constraints,
+                               new_facet_type_info.extend_named_constraints))) {
         new_constraint = {
             .named_constraint_id = old_constraint.named_constraint_id,
             .specific_id = pop_specific(old_constraint.specific_id)};
@@ -273,8 +274,8 @@ static auto PopOperand(Context& context, Worklist& worklist,
           old_facet_type_info.self_impls_constraints.size(),
           SemIR::SpecificInterface::None);
       for (auto [old_constraint, new_constraint] : llvm::reverse(
-               llvm::zip(old_facet_type_info.self_impls_constraints,
-                         new_facet_type_info.self_impls_constraints))) {
+               llvm::zip_equal(old_facet_type_info.self_impls_constraints,
+                               new_facet_type_info.self_impls_constraints))) {
         new_constraint = {
             .interface_id = old_constraint.interface_id,
             .specific_id = pop_specific(old_constraint.specific_id)};
@@ -282,9 +283,9 @@ static auto PopOperand(Context& context, Worklist& worklist,
       new_facet_type_info.extend_constraints.resize(
           old_facet_type_info.extend_constraints.size(),
           SemIR::SpecificInterface::None);
-      for (auto [old_constraint, new_constraint] :
-           llvm::reverse(llvm::zip(old_facet_type_info.extend_constraints,
-                                   new_facet_type_info.extend_constraints))) {
+      for (auto [old_constraint, new_constraint] : llvm::reverse(
+               llvm::zip_equal(old_facet_type_info.extend_constraints,
+                               new_facet_type_info.extend_constraints))) {
         new_constraint = {
             .interface_id = old_constraint.interface_id,
             .specific_id = pop_specific(old_constraint.specific_id)};

toolchain/driver/runtimes_cache_test.cpp

@@ -251,7 +251,7 @@ TEST_F(RuntimesCacheTest, BasicBuild) {
   }
 
   for (const auto& [target, built_runtimes_path] :
-       llvm::zip(targets, built_runtimes_paths)) {
+       llvm::zip_equal(targets, built_runtimes_paths)) {
     SCOPED_TRACE(target);
     auto lookup_result = cache_.Lookup({.target = target});
     ASSERT_THAT(lookup_result, IsSuccess(_));

toolchain/lower/specific_coalescer.cpp

@@ -228,7 +228,7 @@ auto SpecificCoalescer::AreFunctionBodiesEquivalent(
                  "Number of specific calls expected to be the same.");
 
     for (auto [state1_call, state2_call] :
-         llvm::zip(state1.calls, state2.calls)) {
+         llvm::zip_equal(state1.calls, state2.calls)) {
       if (state1_call != state2_call) {
         if (ContainsPair(state1_call, state2_call, non_equivalent_specifics_)) {
           return false;

toolchain/parse/tree_and_subtrees.cpp

@@ -170,13 +170,14 @@ auto TreeAndSubtrees::Print(llvm::raw_ostream& output) const -> void {
 
   // Walk the tree in reverse, just to calculate depths for each node.
   llvm::SmallVector<int> depths(tree_->size(), 0);
-  for (auto [n, depth] : llvm::reverse(llvm::zip(tree_->postorder(), depths))) {
+  for (auto [n, depth] :
+       llvm::reverse(llvm::zip_equal(tree_->postorder(), depths))) {
     for (auto child : children(n)) {
       depths[child.index] = depth + 1;
     }
   }
 
-  for (auto [n, depth] : llvm::zip(tree_->postorder(), depths)) {
+  for (auto [n, depth] : llvm::zip_equal(tree_->postorder(), depths)) {
     PrintNode(output, n, depth, /*preorder=*/false);
     output << ",\n";
   }

toolchain/sem_ir/formatter.cpp

@@ -1090,9 +1090,9 @@ auto Formatter::FormatInstRhs(Inst inst) -> void {
       auto layout = sem_ir_->custom_layouts().Get(type.layout_id);
       out_ << "size=" << layout[CustomLayoutId::SizeIndex]
            << ", align=" << layout[CustomLayoutId::AlignIndex];
-      for (auto [field, offset] :
-           llvm::zip(sem_ir_->struct_type_fields().Get(type.fields_id),
-                     layout.drop_front(CustomLayoutId::FirstFieldIndex))) {
+      for (auto [field, offset] : llvm::zip_equal(
+               sem_ir_->struct_type_fields().Get(type.fields_id),
+               layout.drop_front(CustomLayoutId::FirstFieldIndex))) {
         out_ << ", .";
         FormatName(field.name_id);
         out_ << "@" << offset << ": ";

toolchain/sem_ir/stringify.cpp

@@ -654,7 +654,7 @@ class Stringifier {
     step_stack_->PushString("}");
     llvm::ListSeparator sep;
     for (auto [field, value_inst_id] :
-         llvm::reverse(llvm::zip(fields, field_values))) {
+         llvm::reverse(llvm::zip_equal(fields, field_values))) {
       step_stack_->Push(".", field.name_id, " = ", value_inst_id, &sep);
     }
   }