From 58f86723fc45acc26fd460d0db5e3f46656b1c39 Mon Sep 17 00:00:00 2001
From: robot-clickhouse <robot-clickhouse@users.noreply.github.com>
Date: Tue, 21 May 2024 11:03:49 +0000
Subject: [PATCH] Backport #63753 to 24.3: Allow cast from Array(Nothing) to
 Map(Nothing, Nothing)

---
 src/Functions/FunctionsConversion.cpp                | 7 +++++++
 tests/queries/0_stateless/01787_map_remote.reference | 3 +++
 tests/queries/0_stateless/01787_map_remote.sql       | 6 ++++++
 3 files changed, 16 insertions(+)

diff --git a/src/Functions/FunctionsConversion.cpp b/src/Functions/FunctionsConversion.cpp
index 7049ca44110..4694f98ad50 100644
--- a/src/Functions/FunctionsConversion.cpp
+++ b/src/Functions/FunctionsConversion.cpp
@@ -1,5 +1,6 @@
 #include <type_traits>
 
+#include <AggregateFunctions/IAggregateFunction.h>
 #include <IO/WriteBufferFromVector.h>
 #include <IO/ReadBufferFromMemory.h>
 #include <IO/Operators.h>
@@ -3762,6 +3763,12 @@ private:
         }
         else if (const auto * from_array = typeid_cast<const DataTypeArray *>(from_type_untyped.get()))
         {
+            if (typeid_cast<const DataTypeNothing *>(from_array->getNestedType().get()))
+                return [nested = to_type->getNestedType()](ColumnsWithTypeAndName &, const DataTypePtr &, const ColumnNullable *, size_t size)
+                {
+                    return ColumnMap::create(nested->createColumnConstWithDefaultValue(size)->convertToFullColumnIfConst());
+                };
+
             const auto * nested_tuple = typeid_cast<const DataTypeTuple *>(from_array->getNestedType().get());
             if (!nested_tuple || nested_tuple->getElements().size() != 2)
                 throw Exception(
diff --git a/tests/queries/0_stateless/01787_map_remote.reference b/tests/queries/0_stateless/01787_map_remote.reference
index c7828769f9f..c411899c87c 100644
--- a/tests/queries/0_stateless/01787_map_remote.reference
+++ b/tests/queries/0_stateless/01787_map_remote.reference
@@ -2,3 +2,6 @@
 {'a':1,'b':2}
 {'a':1,'b':2}
 {'a':1,'b':2}
+{}
+{}
+{'':''}
diff --git a/tests/queries/0_stateless/01787_map_remote.sql b/tests/queries/0_stateless/01787_map_remote.sql
index 217308e5141..e169ed62781 100644
--- a/tests/queries/0_stateless/01787_map_remote.sql
+++ b/tests/queries/0_stateless/01787_map_remote.sql
@@ -1,2 +1,8 @@
 SELECT map('a', 1, 'b', 2) FROM remote('127.0.0.{1,2}', system, one);
 SELECT map('a', 1, 'b', 2) FROM remote('127.0.0.{1,2}');
+
+SELECT map() from remote('127.0.0.{1,2}', system,one);
+
+drop table if exists bug_repro_local;
+CREATE TABLE bug_repro_local (`attributes` Map(LowCardinality(String), String)) ENGINE = Log as select map('','');
+SELECT if(1, attributes, map()) from remote('127.0.0.{1,2}', currentDatabase(), bug_repro_local) limit 1;