Fix ParamInfo documentation and annotations

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/MainProxies.scala

@@ -258,11 +258,11 @@ object MainProxies {
           *   defn.MainAnnotationParameterInfo_withDocumentation -> List(Literal("my param x")))
           */
         for doc <- documentation.argDocs.get(param) do
-          paramInfos.withProperty(defn.MainAnnotationParameterInfo_withDocumentation, List(Literal(Constant(doc))))
+          paramInfos = paramInfos.withProperty(defn.MainAnnotationParameterInfo_withDocumentation, List(Literal(Constant(doc))))
 
         val paramAnnots = paramAnnotations(idx)
         if paramAnnots.nonEmpty then
-          paramInfos.withProperty(defn.MainAnnotationParameterInfo_withAnnotations, paramAnnots.map(instantiateAnnotation).toList)
+          paramInfos = paramInfos.withProperty(defn.MainAnnotationParameterInfo_withAnnotations, paramAnnots.map(instantiateAnnotation).toList)
 
         paramInfos
     end parameterInfos

tests/run/main-annotation-homemade-annot-6.check

@@ -2,7 +2,8 @@ command(
   Array(),
   foo,
   "Foo docs",
-  Seq(    ParameterInfo(name="i", typeName="scala.Int", hasDefault=false, isVarargs=false, documentation=None, annotations=List()),
+  Seq(
+    ParameterInfo(name="i", typeName="scala.Int", hasDefault=false, isVarargs=false, documentation=None, annotations=List()),
     ParameterInfo(name="j", typeName="java.lang.String", hasDefault=true, isVarargs=false, documentation=None, annotations=List())
   )*
 )
@@ -15,7 +16,8 @@ command(
   Array(),
   bar,
   "Bar docs",
-  Seq(    ParameterInfo(name="i", typeName="scala.collection.immutable.List[Int]", hasDefault=false, isVarargs=false, documentation=None, annotations=List()),
+  Seq(
+    ParameterInfo(name="i", typeName="scala.collection.immutable.List[Int]", hasDefault=false, isVarargs=false, documentation=Some("the first parameter"), annotations=ArraySeq(MyParamAnnot(3))),
     ParameterInfo(name="rest", typeName="scala.Int", hasDefault=false, isVarargs=true, documentation=None, annotations=List())
   )*
 )

tests/run/main-annotation-homemade-annot-6.scala

@@ -6,7 +6,7 @@ import scala.annotation.*
  *
  *  @param i the first parameter
  */
-@myMain def bar(i: List[Int], rest: Int*) = println(s"bar($i, ${rest.mkString(", ")})")
+@myMain def bar(@MyParamAnnot(3) i: List[Int], rest: Int*) = println(s"bar($i, ${rest.mkString(", ")})")
 
 object Test:
   def main(args: Array[String]) =
@@ -49,6 +49,9 @@ class myMain extends MainAnnotation:
         println()
   end command
 
+@experimental
+case class MyParamAnnot(n: Int) extends MainAnnotation.ParameterAnnotation
+
 trait Make[T]:
   def make: T