much better solution to problem with trim() on Informix

this problem seems to be specific to trim and not occur
for other varchar functions (hope that's correct!)

Author: gavinking

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/InformixDialect.java

@@ -29,6 +29,7 @@
 import org.hibernate.dialect.Replacer;
 import org.hibernate.dialect.SelectItemReferenceStrategy;
 import org.hibernate.dialect.function.InsertSubstringOverlayEmulation;
+import org.hibernate.dialect.function.TrimFunction;
 import org.hibernate.engine.jdbc.env.spi.IdentifierCaseStrategy;
 import org.hibernate.engine.jdbc.env.spi.IdentifierHelper;
 import org.hibernate.engine.jdbc.env.spi.IdentifierHelperBuilder;
@@ -393,11 +394,17 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		functionRegistry.register( "overlay",
 				new InsertSubstringOverlayEmulation( typeConfiguration, true ) );
 
+		// coalesce() has a bug where it does not accept parameters
+		// as arguments, even with a cast (on Informix 14)
 		functionRegistry.namedDescriptorBuilder( "coalesce" )
 				.setMinArgumentCount( 1 )
 				.setArgumentRenderingMode( SqlAstNodeRenderingMode.INLINE_PARAMETERS )
 				.setArgumentTypeResolver( StandardFunctionArgumentTypeResolvers.ARGUMENT_OR_IMPLIED_RESULT_TYPE )
 				.register();
+
+		// parameter arguments to trim() require a cast
+		functionContributions.getFunctionRegistry().register( "trim",
+				new TrimFunction( this, typeConfiguration, SqlAstNodeRenderingMode.NO_UNTYPED ) );
 	}
 
 	@Override

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/InformixSqlAstTranslator.java

@@ -191,18 +191,6 @@ else if ( expression instanceof Summarization ) {
 		}
 	}
 
-//	@Override
-//	protected void renderNull(Literal literal) {
-//		if ( getParameterRenderingMode() == SqlAstNodeRenderingMode.NO_UNTYPED ) {
-//			renderCasted( literal );
-//		}
-//		else {
-//			int sqlType = literal.getExpressionType().getSingleJdbcMapping().getJdbcType().getJdbcTypeCode();
-//			String nullString = getDialect().getSelectClauseNullString( sqlType, getSessionFactory().getTypeConfiguration() );
-//			appendSql( nullString );
-//		}
-//	}
-
 	@Override
 	protected void renderInsertIntoNoColumns(TableInsertStandard tableInsert) {
 		renderIntoIntoAndTable( tableInsert );
@@ -245,7 +233,7 @@ public void visitValuesTableReference(ValuesTableReference tableReference) {
 	protected boolean shouldEmulateFetchClause(QueryPart queryPart) {
 		// Check if current query part is already row numbering to avoid infinite recursion
 		return useOffsetFetchClause( queryPart ) && getQueryPartForRowNumbering() != queryPart
-			   && getDialect().supportsWindowFunctions() && !isRowsOnlyFetchClauseType( queryPart );
+			&& getDialect().supportsWindowFunctions() && !isRowsOnlyFetchClauseType( queryPart );
 	}
 
 	@Override
@@ -295,26 +283,6 @@ protected void visitArithmeticOperand(Expression expression) {
 		}
 	}
 
-	private static boolean isStringFunctionWithParameterArg(SelfRenderingExpression expression) {
-		return expression instanceof FunctionExpression fn
-			&& expression.getExpressionType() != null
-			&& expression.getExpressionType().getJdbcTypeCount() == 1
-			&& expression.getExpressionType().getSingleJdbcMapping().getJdbcType().isString()
-			&& fn.getArguments().stream().anyMatch( arg -> arg instanceof SqmParameterInterpretation );
-	}
-
-	@Override
-	public void visitSelfRenderingExpression(SelfRenderingExpression expression) {
-		if ( isStringFunctionWithParameterArg( expression ) ) {
-			append( "cast(" );
-			super.visitSelfRenderingExpression( expression );
-			append( " as lvarchar)" );
-		}
-		else {
-			super.visitSelfRenderingExpression( expression );
-		}
-	}
-
 	private static boolean isConcatFunction(Expression expression) {
 		return expression instanceof FunctionExpression fn
 			&& fn.getFunctionName().equals( "concat" );