[YQL-15020] Revert declare override part of last commit. Add warning instead

ref:06759ce43d6fd1d3c3442f52b6650aed6a81115f

6 files changed, 24 insertions, 6 deletions

diff --git a/ydb/library/yql/core/issue/protos/issue_id.proto b/ydb/library/yql/core/issue/protos/issue_id.proto
index d61770a1c93..5759dfe5020 100644
--- a/ydb/library/yql/core/issue/protos/issue_id.proto
+++ b/ydb/library/yql/core/issue/protos/issue_id.proto
@@ -136,6 +136,7 @@ message TIssuesIds {
         YQL_TABLE_BINDING_DUPLICATE = 4533;
         YQL_UNUSED_HINT = 4534;
         YQL_DEPRECATED_POSITIONAL_SCHEMA = 4535;
+        YQL_DUPLICATE_DECLARE = 4536;
 
 // yql parser errors
         YQL_NOT_ALLOWED_IN_DISCOVERY = 4600;
diff --git a/ydb/library/yql/core/issue/yql_issue.txt b/ydb/library/yql/core/issue/yql_issue.txt
index 81405dfb6e6..3418b4ac5e2 100644
--- a/ydb/library/yql/core/issue/yql_issue.txt
+++ b/ydb/library/yql/core/issue/yql_issue.txt
@@ -616,3 +616,7 @@ ids {
   code: DQ_GATEWAY_NEED_FALLBACK_ERROR
   severity: S_ERROR
 }
+ids {
+  code: YQL_DUPLICATE_DECLARE
+  severity: S_WARNING
+}
diff --git a/ydb/library/yql/sql/v1/context.cpp b/ydb/library/yql/sql/v1/context.cpp
index 6107645e711..72bd5c5f1dd 100644
--- a/ydb/library/yql/sql/v1/context.cpp
+++ b/ydb/library/yql/sql/v1/context.cpp
@@ -281,8 +281,13 @@ TNodePtr TContext::UniversalAlias(const TString& baseName, TNodePtr&& node) {
     return BuildAtom(node->GetPos(), alias, TNodeFlags::Default);
 }
 
+bool TContext::IsAlreadyDeclared(const TString& varName) const {
+    return Variables.find(varName) != Variables.end();
+}
+
 void TContext::DeclareVariable(const TString& varName, const TNodePtr& typeNode) {
-    Variables[varName] = typeNode;
+    auto inserted = Variables.emplace(varName, typeNode);
+    YQL_ENSURE(inserted.second);
 }
 
 bool TContext::AddExport(TPosition pos, const TString& name) {
diff --git a/ydb/library/yql/sql/v1/context.h b/ydb/library/yql/sql/v1/context.h
index 399646d66b5..359e419063a 100644
--- a/ydb/library/yql/sql/v1/context.h
+++ b/ydb/library/yql/sql/v1/context.h
@@ -159,6 +159,7 @@ namespace NSQLTranslationV1 {
             return IntoHeading;
         }
 
+        bool IsAlreadyDeclared(const TString& varName) const;
         void DeclareVariable(const TString& varName, const TNodePtr& typeNode);
 
         bool AddExport(TPosition symbolPos, const TString& symbolName);
diff --git a/ydb/library/yql/sql/v1/sql.cpp b/ydb/library/yql/sql/v1/sql.cpp
index bc9bf6b9515..ff7be4bc3b0 100644
--- a/ydb/library/yql/sql/v1/sql.cpp
+++ b/ydb/library/yql/sql/v1/sql.cpp
@@ -9007,8 +9007,13 @@ bool TSqlQuery::DeclareStatement(const TRule_declare_stmt& stmt) {
         Ctx.Error(varPos) << "Can not use anonymous name '" << varName << "' in DECLARE statement";
         return false;
     }
-    varName = PushNamedAtom(varPos, varName);
-    Ctx.DeclareVariable(varName, typeNode);
+
+    if (Ctx.IsAlreadyDeclared(varName)) {
+        Ctx.Warning(varPos, TIssuesIds::YQL_DUPLICATE_DECLARE) << "Duplicate declaration of '" << varName << "' will be ignored";
+    } else {
+        PushNamedAtom(varPos, varName);
+        Ctx.DeclareVariable(varName, typeNode);
+    }
     return true;
 }
 
@@ -10096,7 +10101,8 @@ TNodePtr TSqlQuery::Build(const TSQLv1ParserAST& ast) {
             }
 
             TNodePtr typeNode = BuildBuiltinFunc(Ctx, Ctx.Pos(), "ParseType", { BuildLiteralRawString(Ctx.Pos(), type) });
-            varName = PushNamedAtom(Ctx.Pos(), varName);
+            PushNamedAtom(Ctx.Pos(), varName);
+            // no duplicates are possible at this stage
             Ctx.DeclareVariable(varName, typeNode);
         }
     }
diff --git a/ydb/library/yql/sql/v1/sql_ut.cpp b/ydb/library/yql/sql/v1/sql_ut.cpp
index a8300b3624a..c9c6b0ecd6e 100644
--- a/ydb/library/yql/sql/v1/sql_ut.cpp
+++ b/ydb/library/yql/sql/v1/sql_ut.cpp
@@ -4297,15 +4297,16 @@ Y_UNIT_TEST_SUITE(ExternalDeclares) {
         UNIT_ASSERT_VALUES_EQUAL(1, elementStat["declare"]);
     }
 
-    Y_UNIT_TEST(DeclareOverridesExteralDeclares) {
+    Y_UNIT_TEST(NoDeclareOverrides) {
         NSQLTranslation::TTranslationSettings settings;
         settings.DeclaredNamedExprs["foo"] = "String";
         auto res = SqlToYqlWithSettings("declare $foo as Int32; select $foo;", settings);
         UNIT_ASSERT(res.IsOk());
+        UNIT_ASSERT_NO_DIFF(Err2Str(res), "<main>:1:9: Warning: Duplicate declaration of '$foo' will be ignored, code: 4536\n");
 
         TVerifyLineFunc verifyLine = [](const TString& word, const TString& line) {
             if (word == "declare") {
-                UNIT_ASSERT_VALUES_UNEQUAL(TString::npos, line.find(R"__((declare $foo (DataType 'Int32)))__"));
+                UNIT_ASSERT_VALUES_UNEQUAL(TString::npos, line.find(R"__((declare $foo (DataType 'String)))__"));
             }
         };