Fix constant folding for expressions depends from subqueries result

Do not use subquery result, when value is unknown, for constant folding.

v2: fix simple subqueries, fixes 00597_push_down_predicate.
v3:
- use identity over introducing yet another cast analog (as suggested by @akuzm)
- simpler suitable_for_const_folding check
v4: use identity(cast()) since only cast() can provide corrent type (for
data types that does not have it's own type, i.e. DateTime)
v5: do not optimize consts if only_analyze isset, regardless the block
content

src/Interpreters/ExecuteScalarSubqueriesVisitor.cpp

@@ -168,6 +168,16 @@ void ExecuteScalarSubqueriesMatcher::visit(const ASTSubquery & subquery, ASTPtr
         lit->alias = subquery.alias;
         lit->prefer_alias_to_column_name = subquery.prefer_alias_to_column_name;
         ast = addTypeConversionToAST(std::move(lit), scalar.safeGetByPosition(0).type->getName());
+
+        /// If only analyze was requested the expression is not suitable for constant folding, disable it.
+        if (data.only_analyze)
+        {
+            ast->as<ASTFunction>()->alias.clear();
+            auto func = makeASTFunction("identity", std::move(ast));
+            func->alias = subquery.alias;
+            func->prefer_alias_to_column_name = subquery.prefer_alias_to_column_name;
+            ast = std::move(func);
+        }
     }
     else
     {

tests/queries/0_stateless/00597_push_down_predicate.reference

@@ -114,8 +114,9 @@ FROM
 (
     SELECT
         1 AS id,
-        cast(1, \'UInt8\') AS subquery
+        identity(cast(1, \'UInt8\')) AS subquery
 )
+WHERE subquery = 1
 1	1
 SELECT
     a,

tests/queries/0_stateless/01611_constant_folding_subqueries.reference

@@ -0,0 +1,9 @@
+-- { echo }
+SELECT * FROM (SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n)) FORMAT CSV;
+1,10
+SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n) FORMAT CSV;
+1,10
+EXPLAIN SYNTAX SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n);
+SELECT
+    identity(cast(0, \'UInt64\')) AS n,
+    toUInt64(10 / n)

tests/queries/0_stateless/01611_constant_folding_subqueries.sql

@@ -0,0 +1,4 @@
+-- { echo }
+SELECT * FROM (SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n)) FORMAT CSV;
+SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n) FORMAT CSV;
+EXPLAIN SYNTAX SELECT (SELECT * FROM system.numbers LIMIT 1 OFFSET 1) AS n, toUInt64(10 / n);