Report error for task.hash/task.workDir in process script section

src/main/java/nextflow/script/control/TypeCheckingVisitorEx.java

@@ -39,12 +39,14 @@
 import nextflow.script.types.Channel;
 import nextflow.script.types.ParamsMap;
 import nextflow.script.types.Record;
+import nextflow.script.types.TaskConfig;
 import nextflow.script.types.Tuple;
 import nextflow.script.types.TypesEx;
 import nextflow.script.types.Value;
 import org.codehaus.groovy.ast.ASTNode;
 import org.codehaus.groovy.ast.ClassHelper;
 import org.codehaus.groovy.ast.ClassNode;
+import org.codehaus.groovy.ast.CodeVisitorSupport;
 import org.codehaus.groovy.ast.FieldNode;
 import org.codehaus.groovy.ast.GenericsType;
 import org.codehaus.groovy.ast.MethodNode;
@@ -98,6 +100,7 @@ public class TypeCheckingVisitorEx extends ScriptVisitorSupport {
     private static final ClassNode PATH_TYPE = ClassHelper.makeCached(Path.class);
     private static final ClassNode PARAMS_TYPE = ClassHelper.makeCached(ParamsMap.class);
     private static final ClassNode RECORD_TYPE = ClassHelper.makeCached(Record.class);
+    private static final ClassNode TASK_CONFIG_TYPE = ClassHelper.makeCached(TaskConfig.class);
     private static final ClassNode TUPLE_TYPE = ClassHelper.makeCached(Tuple.class);
     private static final ClassNode VALUE_TYPE = ClassHelper.makeCached(Value.class);
 
@@ -228,12 +231,15 @@ public void visitProcessV2(ProcessNodeV2 node) {
         visitProcessDirectives(node.directives);
         visit(node.stagers);
         if( !(node.when instanceof EmptyExpression) )
-            addError("Process `when` section is not supported with static typing -- use conditinal logic in the calling workflow instead", node.when);
+            addError("Process `when` section is not supported with static typing -- use conditional logic in the calling workflow instead", node.when);
         visit(node.when);
         visit(node.exec);
         visit(node.stub);
         visit(node.outputs);
         visitProcessTopics(node.topics);
+        if( !"exec".equals(node.type) )
+            checkTaskScriptProperties(node.exec);
+        checkTaskScriptProperties(node.stub);
     }
 
     private void visitProcessDirectives(Statement block) {
@@ -261,6 +267,37 @@ private void visitProcessTopics(Statement block) {
         }
     }
 
+    /**
+     * Report an error for each use of a restricted task property (e.g.
+     * `task.hash`, `task.workDir`) in the process script section.
+     *
+     * These properties depend on the task hash, which in turn is computed
+     * from the process script, so using them in the script creates a
+     * circular dependency.
+     *
+     * @param block
+     */
+    private void checkTaskScriptProperties(Statement block) {
+        if( block != null )
+            block.visit(new TaskScriptPropertyVisitor());
+    }
+
+    private class TaskScriptPropertyVisitor extends CodeVisitorSupport {
+
+        private static final List<String> RESTRICTED_TASK_PROPERTIES = List.of("hash", "workDir");
+
+        @Override
+        public void visitPropertyExpression(PropertyExpression node) {
+            super.visitPropertyExpression(node);
+            var property = node.getPropertyAsString();
+            if( !RESTRICTED_TASK_PROPERTIES.contains(property) )
+                return;
+            if( !TASK_CONFIG_TYPE.equals(getType(node.getObjectExpression())) )
+                return;
+            addError("`task." + property + "` is not defined in the process `script:` section", node);
+        }
+    }
+
     @Override
     public void visitFunction(FunctionNode node) {
         // visit parameters and code
@@ -388,7 +425,7 @@ private void applyTupleAssignment(TupleExpression target, ClassNode sourceType)
             addError("Tuple assignment is not compatible with type " + TypesEx.getName(sourceType), target);
             return;
         }
-        
+
         var vars = target.getExpressions();
         var gts = sourceType.getGenericsTypes();
         if( gts == null )

src/test/groovy/nextflow/script/types/TypeCheckingTest.groovy

@@ -993,6 +993,79 @@ class TypeCheckingTest extends Specification {
         )
     }
 
+    def 'should report error for task.hash and task.workDir in the process script' () {
+        when:
+        def errors = getErrors(
+            '''\
+            nextflow.enable.types = true
+
+            process hello {
+                script:
+                "echo ${task.hash} > ${task.workDir}/out.txt"
+            }
+            '''
+        )
+        then:
+        errors.size() == 2
+        errors[0].getStartLine() == 5
+        errors[0].getOriginalMessage() == "`task.hash` is not defined in the process `script:` section"
+        errors[1].getStartLine() == 5
+        errors[1].getOriginalMessage() == "`task.workDir` is not defined in the process `script:` section"
+    }
+
+    def 'should report error for task.hash and task.workDir in the process stub' () {
+        when:
+        def errors = getErrors(
+            '''\
+            nextflow.enable.types = true
+
+            process hello {
+                script:
+                'echo hello'
+
+                stub:
+                "echo ${task.hash} > ${task.workDir}/out.txt"
+            }
+            '''
+        )
+        then:
+        errors.size() == 2
+        errors[0].getStartLine() == 8
+        errors[0].getOriginalMessage() == "`task.hash` is not defined in the process `script:` section"
+        errors[1].getStartLine() == 8
+        errors[1].getOriginalMessage() == "`task.workDir` is not defined in the process `script:` section"
+    }
+
+    def 'should allow other task properties in the process script' () {
+        expect:
+        check(
+            '''\
+            nextflow.enable.types = true
+
+            process hello {
+                script:
+                "echo ${task.cpus} ${task.process} ${task.attempt}"
+            }
+            ''',
+            null
+        )
+    }
+
+    def 'should allow task.hash and task.workDir in the process exec section' () {
+        expect:
+        check(
+            '''\
+            nextflow.enable.types = true
+
+            process hello {
+                exec:
+                println "${task.hash} ${task.workDir}"
+            }
+            ''',
+            null
+        )
+    }
+
     def 'should resolve record type' () {
         when:
         def exp = parseExpression(