HHH-17002, HHH-18820, HHH-19391, HHH-18514 standardize on var_ prefix and reenable a check

Author: gavinking

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/AbstractSqmStatement.java

@@ -103,6 +103,6 @@ public Set<ParameterExpression<?>> getParameters() {
 
 	@Override
 	public String generateAlias() {
-		return "t_" + (++aliasCounter);
+		return "var_" + (++aliasCounter);
 	}
 }

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/domain/AbstractSqmAttributeJoin.java

@@ -93,11 +93,12 @@ public void clearFetched() {
 	}
 
 	private void validateFetchAlias(String alias) {
-//		if ( fetchJoin && alias != null && nodeBuilder().isJpaQueryComplianceEnabled() ) {
-//			throw new IllegalStateException(
-//					"The JPA specification does not permit specifying an alias for fetch joins."
-//			);
-//		}
+		if ( fetchJoin && alias != null && !alias.startsWith( "var_" )
+				&& nodeBuilder().isJpaQueryComplianceEnabled() ) {
+			throw new IllegalStateException(
+					"The JPA specification does not permit specifying an alias for fetch joins."
+			);
+		}
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/domain/AbstractSqmFrom.java

@@ -976,6 +976,16 @@ public JpaExpression<?> id() {
 	private int aliasCounter = 0;
 
 	private String generateAlias() {
-		return alias + "_" + (++aliasCounter);
+		final String prefix;
+		if ( alias == null ) {
+			prefix = "var_";
+		}
+		else if ( alias.startsWith( "var_" ) ) {
+			prefix = alias;
+		}
+		else {
+			prefix = "var_" + alias;
+		}
+		return prefix + "_" + (++aliasCounter);
 	}
 }

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/select/SqmSelectStatement.java

@@ -626,6 +626,6 @@ else if ( !newSelections.contains( selection ) ) {
 
 	@Override
 	public String generateAlias() {
-		return "t_" + (++aliasCounter);
+		return "var_" + (++aliasCounter);
 	}
 }