Merge pull request scala#11838 from dotty-staging/fix-10927

Fix name generation for anonymous given of infix types.

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

@@ -999,12 +999,16 @@ object desugar {
           case tree: TypeDef => tree.name.toString
           case tree: AppliedTypeTree if followArgs && tree.args.nonEmpty =>
             s"${apply(x, tree.tpt)}_${extractArgs(tree.args)}"
+          case InfixOp(left, op, right) =>
+            if followArgs then s"${op.name}_${extractArgs(List(left, right))}"
+            else op.name.toString
           case tree: LambdaTypeTree =>
             apply(x, tree.body)
           case tree: Tuple =>
             extractArgs(tree.trees)
           case tree: Function if tree.args.nonEmpty =>
-            if (followArgs) s"${extractArgs(tree.args)}_to_${apply("", tree.body)}" else "Function"
+            if followArgs then s"${extractArgs(tree.args)}_to_${apply("", tree.body)}"
+            else "Function"
           case _ => foldOver(x, tree)
         }
       else x

tests/neg/i10927.scala

@@ -0,0 +1,23 @@
+trait Transition[From, To]
+
+infix type ==>[From, To] = Transition[From, To]
+
+type A = A.type
+object A
+
+type B = B.type
+object B
+
+type C = C.type
+object C
+
+// Compiles
+given (A ==> B) = ???
+
+// was Compile error
+given (A ==> C) = ???
+
+given ==>[A, C] = ???  // error: double definition
+
+given List[A ==> B] = ???
+given List[A ==> C] = ???   // error: double definition

tests/pos/i10927.scala

@@ -0,0 +1,18 @@
+trait Transition[From, To]
+
+infix type ==>[From, To] = Transition[From, To]
+
+type A = A.type
+object A
+
+type B = B.type
+object B
+
+type C = C.type
+object C
+
+// Compiles
+given (A ==> B) = ???
+
+// was Compile error
+given (A ==> C) = ???

tests/semanticdb/expect/Enums.expect.scala

@@ -47,12 +47,12 @@ object Enums/*<-_empty_::Enums.*/:
     case Refl/*<-_empty_::Enums.`<:<`.Refl#*/[C/*<-_empty_::Enums.`<:<`.Refl#[C]*/]() extends (C/*->_empty_::Enums.`<:<`.Refl#[C]*/ <:</*->_empty_::Enums.`<:<`#*/ C/*->_empty_::Enums.`<:<`.Refl#[C]*/)
 
   object <:</*<-_empty_::Enums.`<:<`.*/ :
-    given [T]: (T/*<-_empty_::Enums.`<:<`.given_T().*//*<-_empty_::Enums.`<:<`.given_T().[T]*//*->_empty_::Enums.`<:<`.given_T().[T]*/ <:</*->_empty_::Enums.`<:<`#*/ T/*->_empty_::Enums.`<:<`.given_T().[T]*/) = Refl/*->_empty_::Enums.`<:<`.Refl.*//*->_empty_::Enums.`<:<`.Refl.apply().*/()
+    given [T]: (T <:< T/*<-_empty_::Enums.`<:<`.`given_<:<_T_T`().*//*<-_empty_::Enums.`<:<`.`given_<:<_T_T`().[T]*//*->_empty_::Enums.`<:<`.`given_<:<_T_T`().[T]*//*->_empty_::Enums.`<:<`#*//*->_empty_::Enums.`<:<`.`given_<:<_T_T`().[T]*/) = Refl/*->_empty_::Enums.`<:<`.Refl.*//*->_empty_::Enums.`<:<`.Refl.apply().*/()
 
   extension [A/*<-_empty_::Enums.unwrap().[A]*/, B/*<-_empty_::Enums.unwrap().[B]*/](opt/*<-_empty_::Enums.unwrap().(opt)*/: Option/*->scala::Option#*/[A/*->_empty_::Enums.unwrap().[A]*/]) def unwrap/*<-_empty_::Enums.unwrap().*/(using ev/*<-_empty_::Enums.unwrap().(ev)*/: A/*->_empty_::Enums.unwrap().[A]*/ <:</*->_empty_::Enums.`<:<`#*/ Option/*->scala::Option#*/[B/*->_empty_::Enums.unwrap().[B]*/]): Option/*->scala::Option#*/[B/*->_empty_::Enums.unwrap().[B]*/] = ev/*->_empty_::Enums.unwrap().(ev)*/ match
     case Refl/*->_empty_::Enums.`<:<`.Refl.*//*->_empty_::Enums.`<:<`.Refl.unapply().*/() => opt/*->_empty_::Enums.unwrap().(opt)*/.flatMap/*->scala::Option#flatMap().*/(identity/*->scala::Predef.identity().*//*->local0*/[Option/*->scala::Option#*/[B/*->_empty_::Enums.unwrap().[B]*/]])
 
-  val some1/*<-_empty_::Enums.some1.*/ = Some/*->scala::Some.*//*->scala::Some.apply().*/(Some/*->scala::Some.*//*->scala::Some.apply().*/(1)).unwrap/*->_empty_::Enums.unwrap().*//*->_empty_::Enums.`<:<`.given_T().*/
+  val some1/*<-_empty_::Enums.some1.*/ = Some/*->scala::Some.*//*->scala::Some.apply().*/(Some/*->scala::Some.*//*->scala::Some.apply().*/(1)).unwrap/*->_empty_::Enums.unwrap().*//*->_empty_::Enums.`<:<`.`given_<:<_T_T`().*/
 
   enum Planet/*<-_empty_::Enums.Planet#*/(mass/*<-_empty_::Enums.Planet#mass.*/: Double/*->scala::Double#*/, radius/*<-_empty_::Enums.Planet#radius.*/: Double/*->scala::Double#*/) extends Enum/*->java::lang::Enum#*/[Planet/*->_empty_::Enums.Planet#*/]/*->java::lang::Enum#`<init>`().*/:
     private final val G/*<-_empty_::Enums.Planet#G.*/ = 6.67300E-11

tests/semanticdb/metac.expect

@@ -840,10 +840,10 @@ _empty_/Enums.`<:<`.Refl.toString(). => method toString
 _empty_/Enums.`<:<`.Refl.unapply(). => method unapply
 _empty_/Enums.`<:<`.Refl.unapply().(x$1) => param x$1
 _empty_/Enums.`<:<`.Refl.unapply().[C] => typeparam C
+_empty_/Enums.`<:<`.`given_<:<_T_T`(). => final implicit method given_<:<_T_T
+_empty_/Enums.`<:<`.`given_<:<_T_T`().[T] => typeparam T
 _empty_/Enums.`<:<`.fromOrdinal(). => method fromOrdinal
 _empty_/Enums.`<:<`.fromOrdinal().(ordinal) => param ordinal
-_empty_/Enums.`<:<`.given_T(). => final implicit method given_T
-_empty_/Enums.`<:<`.given_T().[T] => typeparam T
 _empty_/Enums.some1. => val method some1
 _empty_/Enums.unwrap(). => method unwrap
 _empty_/Enums.unwrap().(ev) => implicit param ev
@@ -962,11 +962,11 @@ Occurrences:
 [46:34..46:35): C -> _empty_/Enums.`<:<`.Refl#[C]
 [46:35..46:35): -> _empty_/Enums.`<:<`#`<init>`().
 [48:9..48:12): <:< <- _empty_/Enums.`<:<`.
-[49:10..49:17): [T]: (T <- _empty_/Enums.`<:<`.given_T().
-[49:11..49:12): T <- _empty_/Enums.`<:<`.given_T().[T]
-[49:16..49:17): T -> _empty_/Enums.`<:<`.given_T().[T]
+[49:10..49:23): [T]: (T <:< T <- _empty_/Enums.`<:<`.`given_<:<_T_T`().
+[49:11..49:12): T <- _empty_/Enums.`<:<`.`given_<:<_T_T`().[T]
+[49:16..49:17): T -> _empty_/Enums.`<:<`.`given_<:<_T_T`().[T]
 [49:18..49:21): <:< -> _empty_/Enums.`<:<`#
-[49:22..49:23): T -> _empty_/Enums.`<:<`.given_T().[T]
+[49:22..49:23): T -> _empty_/Enums.`<:<`.`given_<:<_T_T`().[T]
 [49:27..49:31): Refl -> _empty_/Enums.`<:<`.Refl.
 [49:31..49:31): -> _empty_/Enums.`<:<`.Refl.apply().
 [51:13..51:14): A <- _empty_/Enums.unwrap().[A]
@@ -997,7 +997,7 @@ Occurrences:
 [54:19..54:23): Some -> scala/Some.
 [54:23..54:23): -> scala/Some.apply().
 [54:28..54:34): unwrap -> _empty_/Enums.unwrap().
-[54:34..54:34): -> _empty_/Enums.`<:<`.given_T().
+[54:34..54:34): -> _empty_/Enums.`<:<`.`given_<:<_T_T`().
 [56:7..56:13): Planet <- _empty_/Enums.Planet#
 [56:13..56:13): <- _empty_/Enums.Planet#`<init>`().
 [56:14..56:18): mass <- _empty_/Enums.Planet#mass.