[CALCITE-7432] NumberFormatException when convert NaN literal to sql

core/src/main/java/org/apache/calcite/rel/rel2sql/SqlImplementor.java

@@ -66,8 +66,10 @@
 import org.apache.calcite.sql.JoinType;
 import org.apache.calcite.sql.SqlAggFunction;
 import org.apache.calcite.sql.SqlBasicCall;
+import org.apache.calcite.sql.SqlBasicTypeNameSpec;
 import org.apache.calcite.sql.SqlBinaryOperator;
 import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlDataTypeSpec;
 import org.apache.calcite.sql.SqlDialect;
 import org.apache.calcite.sql.SqlDynamicParam;
 import org.apache.calcite.sql.SqlIdentifier;
@@ -1493,7 +1495,7 @@
   }
 
   /** Converts a {@link RexLiteral} to a {@link SqlLiteral}. */
   public static SqlNode toSql(RexLiteral literal) {
     SqlTypeName typeName = literal.getTypeName();
     switch (typeName) {
     case SYMBOL:
@@ -1536,8 +1538,16 @@
     case NUMERIC:
     case EXACT_NUMERIC: {
       if (SqlTypeName.APPROX_TYPES.contains(typeName)) {
-        return SqlLiteral.createApproxNumeric(
-            castNonNull(literal.getValueAs(Double.class)).toString(), POS);
+        final Double d = castNonNull(literal.getValueAs(Double.class));
+        // BigDecimal cannot represent IEEE 754 special values (NaN, ±Infinity).
+        if (!Double.isFinite(d)) {
+          final SqlNode strLiteral =
+              SqlLiteral.createCharString(d.toString(), POS);
+          final SqlDataTypeSpec typeSpec =
+              new SqlDataTypeSpec(new SqlBasicTypeNameSpec(typeName, POS), POS);
+          return SqlStdOperatorTable.CAST.createCall(POS, strLiteral, typeSpec);
+        }
+        return SqlLiteral.createApproxNumeric(d.toString(), POS);
       } else {
         return SqlLiteral.createExactNumeric(
             castNonNull(literal.getValueAs(BigDecimal.class)).toPlainString(), POS);

core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java

@@ -11913,5 +11913,39 @@ public Sql schema(CalciteAssert.SchemaSpec schemaSpec) {
         .schema(CalciteAssert.SchemaSpec.JDBC_SCOTT)
         .ok(expected2);
   }
+  /**
+   * Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-7432">[CALCITE-7432]
+   * NumberFormatException when convert `NaN` literal to sql</a>.
+   *
+   * <p>Tests support for all IEEE 754 floating-point special values:
+   * NaN, positive/negative infinity, signed zero, and subnormal values.
+   */
+  @Test void testCastFloatingPointSpecialValuesToDouble() {
+    // Test NaN
+    sql("select cast('NaN' as DOUBLE)")
+        .ok("SELECT *\n"
+            + "FROM (VALUES (CAST('NaN' AS DOUBLE))) AS \"t\" (\"EXPR$0\")");
+
+    // Test Positive Infinity
+    sql("select cast('Infinity' as DOUBLE)")
+        .ok("SELECT *\n"
+            + "FROM (VALUES (CAST('Infinity' AS DOUBLE))) AS \"t\" (\"EXPR$0\")");
+
+    // Test Negative Infinity
+    sql("select cast('-Infinity' as DOUBLE)")
+        .ok("SELECT *\n"
+            + "FROM (VALUES (CAST('-Infinity' AS DOUBLE))) AS \"t\" (\"EXPR$0\")");
+
+    // Test Negative Zero
+    sql("select cast('-0.0' as DOUBLE)")
+        .ok("SELECT *\n"
+            + "FROM (VALUES (0E0)) AS \"t\" (\"EXPR$0\")");
+
+    // Test Subnormal values
+    sql("select cast('1e-310' as DOUBLE)")
+        .ok("SELECT *\n"
+            + "FROM (VALUES (1.0E-310)) AS \"t\" (\"EXPR$0\")");
+  }
 
 }