Bring workflow outputs out of preview (#6487)

---------

Signed-off-by: Ben Sherman <bentshermann@gmail.com>

Author: bentsherman

docs/migrations/25-10.md

@@ -33,6 +33,35 @@ This syntax allows you to declare all parameters in one place with explicit type
 
 See {ref}`workflow-params-def` for details.
 
+(workflow-outputs-final)=
+
+<h3>Workflow outputs (out of preview)</h3>
+
+{ref}`Workflow outputs <workflow-output-def>`, introduced in Nextflow 24.04 as a preview feature, have been brought out of preview and can now be used without the `nextflow.preview.output` feature flag.
+
+The final version adds the ability to specify a type annotation for each output declaration:
+
+```nextflow
+workflow {
+    main:
+    ch_samples = // ...
+
+    publish:
+    samples = ch_samples
+}
+
+output {
+    samples: Channel<Map> {
+        path '.'
+        index {
+            path 'samples.csv'
+        }
+    }
+}
+```
+
+See {ref}`migrating-workflow-outputs` to get started.
+
 <h3>Type annotations</h3>
 
 Type annotations are a way to denote the *type* of a variable. They help document and validate pipeline code.

docs/reference/feature-flags.md

@@ -46,8 +46,10 @@ Feature flags are used to introduce experimental or other opt-in features. They
 `nextflow.preview.output`
 : :::{versionadded} 24.04.0
   :::
-: *Experimental: may change in a future release.*
-: When `true`, enables the use of the {ref}`workflow output definition <workflow-output-def>`.
+: :::{deprecated} 25.10.0
+  This feature flag is no longer required to use workflow outputs.
+  :::
+: When `true`, enables the use of {ref}`workflow outputs <workflow-output-def>`.
 
 `nextflow.preview.recursion`
 : *Experimental: may change in a future release.*

docs/workflow.md

@@ -474,19 +474,8 @@ Workflows can also be invoked recursively:
 
 ## Workflow outputs
 
-:::{versionadded} 24.04.0
-:::
-
-:::{versionchanged} 24.10.0
-A second preview version was introduced. See the {ref}`migration notes <workflow-outputs-second-preview>` for details.
-:::
-
-:::{versionchanged} 25.04.0
-A third preview version was introduced. See the {ref}`migration notes <workflow-outputs-third-preview>` for details.
-:::
-
-:::{note}
-This feature requires the `nextflow.preview.output` feature flag to be enabled.
+:::{versionadded} 25.10.0
+This feature is available as a preview in Nextflow {ref}`24.04 <workflow-outputs-first-preview>`, {ref}`24.10 <workflow-outputs-second-preview>`, and {ref}`25.04 <workflow-outputs-third-preview>`.
 :::
 
 A script can define an *output block* which declares the top-level outputs of the workflow. Each output should be assigned in the `publish` section of the entry workflow. Any channel in the workflow can be assigned to an output, including process and subworkflow outputs. This approach is intended to replace the {ref}`publishDir <process-publishdir>` directive.
@@ -505,10 +494,10 @@ process fetch {
 
 workflow {
     main:
-    fetch(params.input)
+    ch_samples = fetch(params.input)
 
     publish:
-    samples = fetch.out
+    samples = ch_samples
 }
 
 output {

modules/nextflow/src/main/groovy/nextflow/NF.groovy

@@ -76,10 +76,6 @@ class NF {
         NextflowMeta.instance.isModuleBinariesEnabled()
     }
 
-    static boolean isOutputDefinitionEnabled() {
-        NextflowMeta.instance.preview.output
-    }
-
     static boolean isRecurseEnabled() {
         NextflowMeta.instance.preview.recursion
     }

modules/nextflow/src/main/groovy/nextflow/NextflowMeta.groovy

@@ -42,7 +42,6 @@ class NextflowMeta {
     static class Preview implements Flags {
         @Deprecated volatile float dsl
         @Deprecated boolean strict
-        boolean output
         boolean recursion
         boolean moduleBinaries
         boolean types
@@ -58,12 +57,6 @@ class NextflowMeta {
             dsl = num
         }
 
-        void setOutput(Boolean output) {
-            if( output )
-                log.warn "WORKFLOW OUTPUT DEFINITION IS A PREVIEW FEATURE - SYNTAX AND FUNCTIONALITY CAN CHANGE IN FUTURE RELEASES"
-            this.output = output
-        }
-
         void setRecursion(Boolean recursion) {
             if( recursion )
                 log.warn "NEXTFLOW RECURSION IS A PREVIEW FEATURE - SYNTAX AND FUNCTIONALITY CAN CHANGE IN FUTURE RELEASES"

modules/nextflow/src/main/groovy/nextflow/script/BaseScript.groovy

@@ -185,8 +185,6 @@ abstract class BaseScript extends Script implements ExecutionContext {
      * @param closure
      */
     protected void output(Closure closure) {
-        if( !NF.outputDefinitionEnabled )
-            throw new IllegalStateException("Workflow output definition requires the `nextflow.preview.output` feature flag")
         if( !entryFlow )
             throw new IllegalStateException("Workflow output definition must be defined after the entry workflow")
         if( ExecutionStack.withinWorkflow() )

modules/nf-lang/src/main/java/nextflow/script/dsl/FeatureFlagDsl.java

@@ -43,12 +43,6 @@ Defines the DSL version (`1` or `2`).
     """)
     public boolean strict;
 
-    @FeatureFlag("nextflow.preview.output")
-    @Description("""
-        When `true`, enables the use of the [workflow output definition](https://nextflow.io/docs/latest/workflow.html#workflow-output-def).
-    """)
-    public boolean previewOutput;
-
     @FeatureFlag("nextflow.preview.recursion")
     @Description("""
         When `true`, enables the use of [process and workflow recursion](https://nextflow.io/docs/latest/workflow.html#process-and-workflow-recursion).

tests-v1/output-dsl.nf

@@ -14,7 +14,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-nextflow.preview.output = true
 
 params.save_bam_bai = false
 

tests/output-dsl.nf

@@ -14,7 +14,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-nextflow.preview.output = true
 nextflow.preview.types = true
 
 params.save_bam_bai = false