chore: avoid Java version mismatch

When developing, the build (both on the command-line and in the IDE)
frequently fails due to usage of unsupported Java language features for
the target Java runtime. This is due to the the Java source version
being set to a newer version than the target Java version. While this
sometimes works, this combination is explicitly disallowed by the Java
compiler. Source version must be equal to or less than the target
version.

This change uses the correct Java toolchain version for each
sub-project. The exception being the core sub-project, since it targets
Java 8 whereas ANTLR requires Java 11+ to run. Instead, the Java
compiler release option is set to Java 8, ensuring that Java 8 bytecode
is produced and that no APIs not present in Java 8 are used.

While numerous code changes are required to adhere to the target Java
language version, there are no functional changes.

Signed-off-by: Mark S. Lewis <[email protected]>

Author: bestbeforetoday

build.gradle.kts

@@ -41,20 +41,10 @@ allprojects {
   repositories { mavenCentral() }
 
   tasks.configureEach<Test> {
-    val javaToolchains = project.extensions.getByType<JavaToolchainService>()
     useJUnitPlatform()
-    javaLauncher.set(javaToolchains.launcherFor { languageVersion.set(JavaLanguageVersion.of(11)) })
     testLogging { exceptionFormat = TestExceptionFormat.FULL }
   }
-  tasks.withType<JavaCompile> {
-    sourceCompatibility = "17"
-    if (project.name != "core") {
-      options.release.set(11)
-    } else {
-      options.release.set(8)
-    }
-    dependsOn(submodulesUpdate)
-  }
+  tasks.withType<JavaCompile> { dependsOn(submodulesUpdate) }
 
   group = "io.substrait"
   version = "${version}"

core/build.gradle.kts

@@ -233,12 +233,12 @@ tasks {
   jar { manifest { from("build/generated/sources/manifest/META-INF/MANIFEST.MF") } }
 }
 
+// Set the release instead of using a Java 8 toolchain since ANTLR requires Java 11+ to run
+tasks.withType<JavaCompile>().configureEach { options.release = 8 }
+
 java {
-  toolchain {
-    languageVersion.set(JavaLanguageVersion.of(17))
-    withJavadocJar()
-    withSourcesJar()
-  }
+  withJavadocJar()
+  withSourcesJar()
 }
 
 configurations { runtimeClasspath { resolutionStrategy.activateDependencyLocking() } }

core/src/main/java/io/substrait/dsl/SubstraitBuilder.java

@@ -87,8 +87,8 @@ private Aggregate aggregate(
       Function<Rel, List<Aggregate.Measure>> measuresFn,
       Optional<Rel.Remap> remap,
       Rel input) {
-    var groupings = groupingsFn.apply(input);
-    var measures = measuresFn.apply(input);
+    List<Aggregate.Grouping> groupings = groupingsFn.apply(input);
+    List<Aggregate.Measure> measures = measuresFn.apply(input);
     return Aggregate.builder()
         .groupings(groupings)
         .measures(measures)
@@ -147,7 +147,7 @@ public Filter filter(Function<Rel, Expression> conditionFn, Rel.Remap remap, Rel
 
   private Filter filter(
       Function<Rel, Expression> conditionFn, Optional<Rel.Remap> remap, Rel input) {
-    var condition = conditionFn.apply(input);
+    Expression condition = conditionFn.apply(input);
     return Filter.builder().input(input).condition(condition).remap(remap).build();
   }
 
@@ -183,7 +183,7 @@ private Join join(
       Optional<Rel.Remap> remap,
       Rel left,
       Rel right) {
-    var condition = conditionFn.apply(new JoinInput(left, right));
+    Expression condition = conditionFn.apply(new JoinInput(left, right));
     return Join.builder()
         .left(left)
         .right(right)
@@ -263,7 +263,7 @@ private NestedLoopJoin nestedLoopJoin(
       Optional<Rel.Remap> remap,
       Rel left,
       Rel right) {
-    var condition = conditionFn.apply(new JoinInput(left, right));
+    Expression condition = conditionFn.apply(new JoinInput(left, right));
     return NestedLoopJoin.builder()
         .left(left)
         .right(right)
@@ -291,8 +291,8 @@ private NamedScan namedScan(
       Iterable<String> columnNames,
       Iterable<Type> types,
       Optional<Rel.Remap> remap) {
-    var struct = Type.Struct.builder().addAllFields(types).nullable(false).build();
-    var namedStruct = NamedStruct.of(columnNames, struct);
+    Type.Struct struct = Type.Struct.builder().addAllFields(types).nullable(false).build();
+    NamedStruct namedStruct = NamedStruct.of(columnNames, struct);
     return NamedScan.builder().names(tableName).initialSchema(namedStruct).remap(remap).build();
   }
 
@@ -315,7 +315,7 @@ private Project project(
       Function<Rel, Iterable<? extends Expression>> expressionsFn,
       Optional<Rel.Remap> remap,
       Rel input) {
-    var expressions = expressionsFn.apply(input);
+    Iterable<? extends Expression> expressions = expressionsFn.apply(input);
     return Project.builder().input(input).expressions(expressions).remap(remap).build();
   }
 
@@ -332,7 +332,7 @@ private Expand expand(
       Function<Rel, Iterable<? extends Expand.ExpandField>> fieldsFn,
       Optional<Rel.Remap> remap,
       Rel input) {
-    var fields = fieldsFn.apply(input);
+    Iterable<? extends Expand.ExpandField> fields = fieldsFn.apply(input);
     return Expand.builder().input(input).fields(fields).remap(remap).build();
   }
 
@@ -363,7 +363,7 @@ private Sort sort(
       Function<Rel, Iterable<? extends Expression.SortField>> sortFieldFn,
       Optional<Rel.Remap> remap,
       Rel input) {
-    var condition = sortFieldFn.apply(input);
+    Iterable<? extends Expression.SortField> condition = sortFieldFn.apply(input);
     return Sort.builder().input(input).sortFields(condition).remap(remap).build();
   }
 
@@ -465,7 +465,7 @@ public Switch switchExpression(
 
   public AggregateFunctionInvocation aggregateFn(
       String namespace, String key, Type outputType, Expression... args) {
-    var declaration =
+    SimpleExtension.AggregateFunctionVariant declaration =
         extensions.getAggregateFunction(SimpleExtension.FunctionAnchor.of(namespace, key));
     return AggregateFunctionInvocation.builder()
         .arguments(Arrays.stream(args).collect(java.util.stream.Collectors.toList()))
@@ -477,7 +477,7 @@ public AggregateFunctionInvocation aggregateFn(
   }
 
   public Aggregate.Grouping grouping(Rel input, int... indexes) {
-    var columns = fieldReferences(input, indexes);
+    List<FieldReference> columns = fieldReferences(input, indexes);
     return Aggregate.Grouping.builder().addAllExpressions(columns).build();
   }
 
@@ -486,7 +486,7 @@ public Aggregate.Grouping grouping(Expression... expressions) {
   }
 
   public Aggregate.Measure count(Rel input, int field) {
-    var declaration =
+    SimpleExtension.AggregateFunctionVariant declaration =
         extensions.getAggregateFunction(
             SimpleExtension.FunctionAnchor.of(
                 DefaultExtensionCatalog.FUNCTIONS_AGGREGATE_GENERIC, "count:any"));
@@ -563,7 +563,7 @@ public Aggregate.Measure sum0(Expression expr) {
   private Aggregate.Measure singleArgumentArithmeticAggregate(
       Expression expr, String functionName, Type outputType) {
     String typeString = ToTypeString.apply(expr.getType());
-    var declaration =
+    SimpleExtension.AggregateFunctionVariant declaration =
         extensions.getAggregateFunction(
             SimpleExtension.FunctionAnchor.of(
                 DefaultExtensionCatalog.FUNCTIONS_ARITHMETIC,
@@ -585,7 +585,7 @@ private Aggregate.Measure singleArgumentArithmeticAggregate(
 
   public Expression.ScalarFunctionInvocation negate(Expression expr) {
     // output type of negate is the same as the input type
-    var outputType = expr.getType();
+    Type outputType = expr.getType();
     return scalarFn(
         DefaultExtensionCatalog.FUNCTIONS_ARITHMETIC,
         String.format("negate:%s", ToTypeString.apply(outputType)),
@@ -611,12 +611,12 @@ public Expression.ScalarFunctionInvocation divide(Expression left, Expression ri
 
   private Expression.ScalarFunctionInvocation arithmeticFunction(
       String fname, Expression left, Expression right) {
-    var leftTypeStr = ToTypeString.apply(left.getType());
-    var rightTypeStr = ToTypeString.apply(right.getType());
-    var key = String.format("%s:%s_%s", fname, leftTypeStr, rightTypeStr);
+    String leftTypeStr = ToTypeString.apply(left.getType());
+    String rightTypeStr = ToTypeString.apply(right.getType());
+    String key = String.format("%s:%s_%s", fname, leftTypeStr, rightTypeStr);
 
-    var isOutputNullable = left.getType().nullable() || right.getType().nullable();
-    var outputType = left.getType();
+    boolean isOutputNullable = left.getType().nullable() || right.getType().nullable();
+    Type outputType = left.getType();
     outputType =
         isOutputNullable
             ? TypeCreator.asNullable(outputType)
@@ -633,14 +633,14 @@ public Expression.ScalarFunctionInvocation equal(Expression left, Expression rig
   public Expression.ScalarFunctionInvocation or(Expression... args) {
     // If any arg is nullable, the output of or is potentially nullable
     // For example: false or null = null
-    var isOutputNullable = Arrays.stream(args).anyMatch(a -> a.getType().nullable());
-    var outputType = isOutputNullable ? N.BOOLEAN : R.BOOLEAN;
+    boolean isOutputNullable = Arrays.stream(args).anyMatch(a -> a.getType().nullable());
+    Type outputType = isOutputNullable ? N.BOOLEAN : R.BOOLEAN;
     return scalarFn(DefaultExtensionCatalog.FUNCTIONS_BOOLEAN, "or:bool", outputType, args);
   }
 
   public Expression.ScalarFunctionInvocation scalarFn(
       String namespace, String key, Type outputType, FunctionArg... args) {
-    var declaration =
+    SimpleExtension.ScalarFunctionVariant declaration =
         extensions.getScalarFunction(SimpleExtension.FunctionAnchor.of(namespace, key));
     return Expression.ScalarFunctionInvocation.builder()
         .declaration(declaration)
@@ -659,7 +659,7 @@ public Expression.WindowFunctionInvocation windowFn(
       WindowBound lowerBound,
       WindowBound upperBound,
       Expression... args) {
-    var declaration =
+    SimpleExtension.WindowFunctionVariant declaration =
         extensions.getWindowFunction(SimpleExtension.FunctionAnchor.of(namespace, key));
     return Expression.WindowFunctionInvocation.builder()
         .declaration(declaration)

core/src/main/java/io/substrait/expression/Expression.java

@@ -762,7 +762,7 @@ public io.substrait.proto.Expression.WindowFunction.BoundsType toProto() {
 
     public static WindowBoundsType fromProto(
         io.substrait.proto.Expression.WindowFunction.BoundsType proto) {
-      for (var v : values()) {
+      for (WindowBoundsType v : values()) {
         if (v.proto == proto) {
           return v;
         }
@@ -903,7 +903,7 @@ public io.substrait.proto.Expression.Subquery.SetPredicate.PredicateOp toProto()
 
     public static PredicateOp fromProto(
         io.substrait.proto.Expression.Subquery.SetPredicate.PredicateOp proto) {
-      for (var v : values()) {
+      for (PredicateOp v : values()) {
         if (v.proto == proto) {
           return v;
         }
@@ -929,7 +929,7 @@ public io.substrait.proto.AggregateFunction.AggregationInvocation toProto() {
     }
 
     public static AggregationInvocation fromProto(AggregateFunction.AggregationInvocation proto) {
-      for (var v : values()) {
+      for (AggregationInvocation v : values()) {
         if (v.proto == proto) {
           return v;
         }
@@ -960,7 +960,7 @@ public io.substrait.proto.AggregationPhase toProto() {
     }
 
     public static AggregationPhase fromProto(io.substrait.proto.AggregationPhase proto) {
-      for (var v : values()) {
+      for (AggregationPhase v : values()) {
         if (v.proto == proto) {
           return v;
         }
@@ -988,7 +988,7 @@ public io.substrait.proto.SortField.SortDirection toProto() {
     }
 
     public static SortDirection fromProto(io.substrait.proto.SortField.SortDirection proto) {
-      for (var v : values()) {
+      for (SortDirection v : values()) {
         if (v.proto == proto) {
           return v;
         }
@@ -1016,7 +1016,7 @@ public io.substrait.proto.Expression.Cast.FailureBehavior toProto() {
 
     public static FailureBehavior fromProto(
         io.substrait.proto.Expression.Cast.FailureBehavior proto) {
-      for (var v : values()) {
+      for (FailureBehavior v : values()) {
         if (v.proto == proto) {
           return v;
         }

core/src/main/java/io/substrait/expression/ExpressionCreator.java

@@ -7,6 +7,7 @@
 import io.substrait.type.Type;
 import io.substrait.util.DecimalUtil;
 import java.math.BigDecimal;
+import java.nio.ByteBuffer;
 import java.time.Instant;
 import java.time.LocalDateTime;
 import java.time.ZoneOffset;
@@ -89,7 +90,7 @@ public static Expression.TimestampLiteral timestamp(boolean nullable, long value
    */
   @Deprecated
   public static Expression.TimestampLiteral timestamp(boolean nullable, LocalDateTime value) {
-    var epochMicro =
+    long epochMicro =
         TimeUnit.SECONDS.toMicros(value.toEpochSecond(ZoneOffset.UTC))
             + TimeUnit.NANOSECONDS.toMicros(value.toLocalTime().getNano());
     return timestamp(nullable, epochMicro);
@@ -127,7 +128,7 @@ public static Expression.TimestampTZLiteral timestampTZ(boolean nullable, long v
    */
   @Deprecated
   public static Expression.TimestampTZLiteral timestampTZ(boolean nullable, Instant value) {
-    var epochMicro =
+    long epochMicro =
         TimeUnit.SECONDS.toMicros(value.getEpochSecond())
             + TimeUnit.NANOSECONDS.toMicros(value.getNano());
     return timestampTZ(nullable, epochMicro);
@@ -195,7 +196,7 @@ public static Expression.IntervalCompoundLiteral intervalCompound(
   }
 
   public static Expression.UUIDLiteral uuid(boolean nullable, ByteString uuid) {
-    var bb = uuid.asReadOnlyByteBuffer();
+    ByteBuffer bb = uuid.asReadOnlyByteBuffer();
     return Expression.UUIDLiteral.builder()
         .nullable(nullable)
         .value(new UUID(bb.getLong(), bb.getLong()))
@@ -237,7 +238,7 @@ public static Expression.DecimalLiteral decimal(
 
   public static Expression.DecimalLiteral decimal(
       boolean nullable, BigDecimal value, int precision, int scale) {
-    var twosComplement = DecimalUtil.encodeDecimalIntoBytes(value, scale, 16);
+    byte[] twosComplement = DecimalUtil.encodeDecimalIntoBytes(value, scale, 16);
 
     return Expression.DecimalLiteral.builder()
         .nullable(nullable)

core/src/main/java/io/substrait/expression/FieldReference.java

@@ -222,7 +222,7 @@ private static FieldReference of(
     Collections.reverse(segments);
     for (int i = 0; i < segments.size(); i++) {
       if (i == 0) {
-        var last = segments.get(0);
+        ReferenceSegment last = segments.get(0);
         reference =
             struct == null ? last.constructOnExpression(expression) : last.constructOnRoot(struct);
       } else {

core/src/main/java/io/substrait/expression/FunctionArg.java

@@ -35,21 +35,21 @@ static FuncArgVisitor<FunctionArgument, RuntimeException> toProto(
       @Override
       public FunctionArgument visitExpr(SimpleExtension.Function fnDef, int argIdx, Expression e)
           throws RuntimeException {
-        var pE = e.accept(expressionVisitor);
+        io.substrait.proto.Expression pE = e.accept(expressionVisitor);
         return FunctionArgument.newBuilder().setValue(pE).build();
       }
 
       @Override
       public FunctionArgument visitType(SimpleExtension.Function fnDef, int argIdx, Type t)
           throws RuntimeException {
-        var pTyp = t.accept(typeVisitor);
+        io.substrait.proto.Type pTyp = t.accept(typeVisitor);
         return FunctionArgument.newBuilder().setType(pTyp).build();
       }
 
       @Override
       public FunctionArgument visitEnumArg(SimpleExtension.Function fnDef, int argIdx, EnumArg ea)
           throws RuntimeException {
-        var enumBldr = FunctionArgument.newBuilder();
+        FunctionArgument.Builder enumBldr = FunctionArgument.newBuilder();
 
         if (ea.value().isPresent()) {
           enumBldr = enumBldr.setEnum(ea.value().get());
@@ -75,18 +75,22 @@ public ProtoFrom(
 
     public FunctionArg convert(
         SimpleExtension.Function funcDef, int argIdx, FunctionArgument fArg) {
-      return switch (fArg.getArgTypeCase()) {
-        case TYPE -> protoTypeConverter.from(fArg.getType());
-        case VALUE -> protoExprConverter.from(fArg.getValue());
-        case ENUM -> {
-          SimpleExtension.EnumArgument enumArgDef =
-              (SimpleExtension.EnumArgument) funcDef.args().get(argIdx);
-          var optionValue = fArg.getEnum();
-          yield EnumArg.of(enumArgDef, optionValue);
-        }
-        default -> throw new UnsupportedOperationException(
-            String.format("Unable to convert FunctionArgument %s.", fArg));
-      };
+      switch (fArg.getArgTypeCase()) {
+        case TYPE:
+          return protoTypeConverter.from(fArg.getType());
+        case VALUE:
+          return protoExprConverter.from(fArg.getValue());
+        case ENUM:
+          {
+            SimpleExtension.EnumArgument enumArgDef =
+                (SimpleExtension.EnumArgument) funcDef.args().get(argIdx);
+            String optionValue = fArg.getEnum();
+            return EnumArg.of(enumArgDef, optionValue);
+          }
+        default:
+          throw new UnsupportedOperationException(
+              String.format("Unable to convert FunctionArgument %s.", fArg));
+      }
     }
   }
 }