Forbid redefined alias in a single path pattern.

src/graph/validator/MatchValidator.cpp

@@ -152,6 +152,7 @@ Status MatchValidator::buildNodeInfo(const MatchPath *path,
   auto steps = path->steps();
   auto *pool = qctx_->objPool();
   nodeInfos.resize(steps + 1);
+  std::unordered_map<std::string, AliasType> nodeAliases;
 
   for (auto i = 0u; i <= steps; i++) {
     auto *node = path->node(i);
@@ -176,7 +177,10 @@ Status MatchValidator::buildNodeInfo(const MatchPath *path,
       anonymous = true;
       alias = vctx_->anonVarGen()->getVar();
     } else {
-      aliases.emplace(alias, AliasType::kNode);
+      if (!nodeAliases.emplace(alias, AliasType::kNode).second) {
+        return Status::SemanticError("`%s': Redefined alias in a single path pattern.",
+                                     alias.c_str());
+      }
     }
     Expression *filter = nullptr;
     if (props != nullptr) {
@@ -196,6 +200,7 @@ Status MatchValidator::buildNodeInfo(const MatchPath *path,
     nodeInfos[i].props = props;
     nodeInfos[i].filter = filter;
   }
+  aliases.merge(nodeAliases);
 
   return Status::OK();
 }

tests/tck/features/match/MultiQueryParts.feature

@@ -201,6 +201,16 @@ Feature: Multi Query Parts
     Then the result should be, in order:
       | scount | lcount |
       | 19     | 110    |
+    When executing query:
+      """
+      MATCH (m:player{name:"Tim Duncan"})-[:like]-(n)--()
+      WITH  m,n
+      MATCH (m)--(n)
+      RETURN count(*) AS scount
+      """
+    Then the result should be, in order:
+      | scount |
+      | 270    |
     # Below scenario is not suppoted for the execution plan has a scan.
     When executing query:
       """
@@ -219,3 +229,8 @@ Feature: Multi Query Parts
       RETURN m
       """
     Then a SemanticError should be raised at runtime: Alias used but not defined: `m'
+    When executing query:
+      """
+      MATCH (v:player)-[e]-(v:team) RETURN v, e
+      """
+    Then a SemanticError should be raised at runtime: `v': Redefined alias in a single path pattern.