[I] GSP layout tags from @CompileStatic TagLib classes are not discoverable as bare method calls [grails-core]

["jamesfredley (via GitHub)" <gi...@apache.org>]

jamesfredley opened a new issue, #15506:
URL: https://github.com/apache/grails-core/issues/15506

   ## Summary
   
   Tags defined in `RenderGrailsLayoutTagLib` (e.g., `pageProperty`, `layoutTitle`, `layoutBody`) cannot be called as bare methods in GSP expression syntax (`${pageProperty(name: 'meta.description')}`). They work correctly with the explicit `g.` namespace prefix (`${g.pageProperty(name: 'meta.description')}`).
   
   The root cause is that `RenderGrailsLayoutTagLib` has `@CompileStatic` at class level, and `DefaultGrailsTagLibClass` tag discovery does not find `Closure`-typed properties on `@CompileStatic` classes.
   
   ## Version
   
   Grails 7.0.x (all versions since 7.0.0-M5, when `RenderGrailsLayoutTagLib` was introduced). Tested on 7.0.9-SNAPSHOT.
   
   ## Steps to Reproduce
   
   1. Create a layout GSP (e.g., `layouts/marketing.gsp`)
   2. Use `pageProperty` as a bare method call in a GSP expression:
      ```gsp
      <meta name="description" content="${pageProperty(name: 'meta.description') ?: 'default'}"/>
      ```
   3. Visit a page that uses this layout
   
   **Expected:** The page renders normally, `pageProperty` resolves to the tag from `RenderGrailsLayoutTagLib`.
   
   **Actual:** 500 error: `No signature of method: ...marketing_gsp.pageProperty() is applicable for argument types: (LinkedHashMap)`
   
   ## Workaround
   
   Using the explicit `g.` namespace prefix works:
   
   ```gsp
   <meta name="description" content="${g.pageProperty(name: 'meta.description') ?: 'default'}"/>
   ```
   
   This is because `g.pageProperty()` goes through `GroovyPage.getProperty("g")` -> `NamespacedTagDispatcher` -> `TagLibraryLookup.lookupTagLibrary()`, which is a different resolution path that works correctly.
   
   ## Root Cause Analysis
   
   ### Tag discovery mechanism
   
   `DefaultGrailsTagLibClass` (line 62-71) discovers tags by iterating metaclass properties:
   
   ```java
   for (MetaProperty prop : GroovySystem.getMetaClassRegistry().getMetaClass(clazz).getProperties()) {
       int modifiers = prop.getModifiers();
       if (Modifier.isStatic(modifiers) || !Modifier.isPublic(modifiers)) {
           continue;
       }
       if (Closure.class.isAssignableFrom(prop.getType())) {
           tags.add(prop.getName());
       }
   }
   ```
   
   When a TagLib class has `@CompileStatic`, Groovy 4 compiles the `Closure` property fields differently. The metaclass property type no longer reports as `Closure`, so `Closure.class.isAssignableFrom(prop.getType())` returns false, and the tags are not registered.
   
   ### Two resolution paths
   
   | Call syntax | Resolution path | Works? |
   |---|---|---|
   | `g.pageProperty(name: ...)` | `GroovyPage.getProperty("g")` -> `NamespacedTagDispatcher.methodMissing` -> `TagLibraryLookup.lookupTagLibrary("g", "pageProperty")` | Yes |
   | `pageProperty(name: ...)` | `ExpandoMetaClass.methodMissing` -> `TagLibraryMetaUtils.methodMissingForTagLib` -> `TagLibraryLookup.lookupTagLibrary("g", "pageProperty")` | No |
   
   Both paths use the same `TagLibraryLookup`. The bare method path fails because the tag was never registered in the lookup's `tagNamespaces` map (due to the property scanning issue above). The `g.` path works because the `NamespacedTagDispatcher` has its own `methodMissing` that still finds the bean.
   
   ### Confirmed by test
   
   Locally removed `@CompileStatic` from `RenderGrailsLayoutTagLib`, published to mavenLocal, and tested: **bare `pageProperty()` works correctly after removal**. Re-adding `@CompileStatic` breaks it again.
   
   ### Affected TagLib
   
   `RenderGrailsLayoutTagLib` in `grails-layout` module is the only framework TagLib with class-level `@CompileStatic`. Other built-in TagLibs (e.g., `ApplicationTagLib`, `FormTagLib`, `RenderTagLib`) do not have class-level `@CompileStatic` and their tags work as bare methods.
   
   ### History
   
   `RenderGrailsLayoutTagLib` was introduced in commit `0be9f5d486` ("revert sitemesh3 upgrade & rename sitemesh -> layout") included in 7.0.0-M5. The class-level `@CompileStatic` was present from its creation. The prior `RenderSitemeshTagLib` (Sitemesh 3, since reverted) did not have `@CompileStatic`.
   
   ## Affected tags
   
   All tags in `RenderGrailsLayoutTagLib`:
   - `pageProperty`
   - `ifPageProperty`
   - `layoutTitle`
   - `layoutHead`
   - `layoutBody`
   - `applyLayout`
   - `content`
   
   ## Note on documentation
   
   The [official pageProperty docs](https://grails.apache.org/docs/7.0.0/ref/Tags%20-%20GSP/pageProperty.html) show `${pageProperty(name:'body.onload')}` without the `g.` prefix, which does not work due to this bug.


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Re: [I] GSP layout tags from @CompileStatic TagLib classes are not discoverable as bare method calls [grails-core]

["jdaugherty (via GitHub)" <gi...@apache.org>]

jdaugherty closed issue #15506: GSP layout tags from @CompileStatic TagLib classes are not discoverable as bare method calls
URL: https://github.com/apache/grails-core/issues/15506


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