Naming anon givens is a fix by renaming

som-snytt · tgodzik · commit 8333a5345d01 · 2025-09-12T19:01:46.000+02:00
[Cherry-picked 6fe3abc]
diff --git a/compiler/src/dotty/tools/dotc/reporting/messages.scala b/compiler/src/dotty/tools/dotc/reporting/messages.scala
@@ -2390,13 +2390,22 @@ extends NamingMsg(DoubleDefinitionID):
   def explain(using Context) =
     def givenAddendum =
       def isGivenName(sym: Symbol) = sym.name.startsWith("given_") // Desugar.inventGivenName
+      def print(tpe: Type): String =
+        def addParams(tpe: Type): List[String] = tpe match
+          case tpe: MethodType =>
+            val s = if tpe.isContextualMethod then i"(${tpe.paramInfos}%, %) =>" else ""
+            s :: addParams(tpe.resType)
+          case tpe: PolyType =>
+            i"[${tpe.paramNames}%, %] =>" :: addParams(tpe.resType)
+          case tpe =>
+            i"$tpe" :: Nil
+        addParams(tpe).mkString(" ")
       if decl.is(Given) && previousDecl.is(Given) && isGivenName(decl) && isGivenName(previousDecl) then
-        i"""
-           |3. Provide an explicit, unique name to given definitions, since the names
-           |   assigned to anonymous givens may clash. For example:
-           |
-           |      given myGiven: ${atPhase(typerPhase)(decl.info)}
-           |"""
+        i"""| Provide an explicit, unique name to given definitions,
+            |   since the names assigned to anonymous givens may clash. For example:
+            |
+            |      given myGiven: ${print(atPhase(typerPhase)(decl.info))}
+            |"""
       else ""
     decl.signature.matchDegree(previousDecl.signature) match
       case FullMatch =>
@@ -2420,15 +2429,15 @@ extends NamingMsg(DoubleDefinitionID):
         |
         |so the compiler cannot keep both: the generated bytecode symbols would collide.
         |
-        |To fix this error, you need to disambiguate the two definitions. You can either:
+        |To fix this error, you must disambiguate the two definitions by doing one of the following:
         |
-        |1. Rename one of the definitions, or
+        |1. Rename one of the definitions.$givenAddendum
         |2. Keep the same names in source but give one definition a distinct
         |   bytecode-level name via `@targetName`; for example:
         |
         |      @targetName("${decl.name.show}_2")
         |      ${atPhase(typerPhase)(decl.showDcl)}
-        |$givenAddendum
+        |
         |Choose the `@targetName` argument carefully: it is the name that will be used
         |when calling the method externally, so it should be unique and descriptive.
         |"""
diff --git a/tests/neg/i23350.check b/tests/neg/i23350.check
@@ -31,9 +31,9 @@
   |
   | so the compiler cannot keep both: the generated bytecode symbols would collide.
   |
-  | To fix this error, you need to disambiguate the two definitions. You can either:
+  | To fix this error, you must disambiguate the two definitions by doing one of the following:
   |
-  | 1. Rename one of the definitions, or
+  | 1. Rename one of the definitions.
   | 2. Keep the same names in source but give one definition a distinct
   |    bytecode-level name via `@targetName`; for example:
   |
diff --git a/tests/neg/i23402.check b/tests/neg/i23402.check
@@ -31,9 +31,9 @@
   |
   | so the compiler cannot keep both: the generated bytecode symbols would collide.
   |
-  | To fix this error, you need to disambiguate the two definitions. You can either:
+  | To fix this error, you must disambiguate the two definitions by doing one of the following:
   |
-  | 1. Rename one of the definitions, or
+  | 1. Rename one of the definitions.
   | 2. Keep the same names in source but give one definition a distinct
   |    bytecode-level name via `@targetName`; for example:
   |
diff --git a/tests/neg/i23832a.check b/tests/neg/i23832a.check
@@ -27,20 +27,19 @@
   |
   | so the compiler cannot keep both: the generated bytecode symbols would collide.
   |
-  | To fix this error, you need to disambiguate the two definitions. You can either:
+  | To fix this error, you must disambiguate the two definitions by doing one of the following:
+  |
+  | 1. Rename one of the definitions. Provide an explicit, unique name to given definitions,
+  |    since the names assigned to anonymous givens may clash. For example:
+  |
+  |       given myGiven: Special[Option[Int]]
   |
-  | 1. Rename one of the definitions, or
   | 2. Keep the same names in source but give one definition a distinct
   |    bytecode-level name via `@targetName`; for example:
   |
   |       @targetName("given_Special_Option_2")
   |       final lazy given val given_Special_Option: Special[Option[Int]]
   |
-  | 3. Provide an explicit, unique name to given definitions, since the names
-  |    assigned to anonymous givens may clash. For example:
-  |
-  |       given myGiven: Special[Option[Int]]
-  |
   | Choose the `@targetName` argument carefully: it is the name that will be used
   | when calling the method externally, so it should be unique and descriptive.
    ---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg/i23832b.check b/tests/neg/i23832b.check
@@ -27,20 +27,19 @@
   |
   | so the compiler cannot keep both: the generated bytecode symbols would collide.
   |
-  | To fix this error, you need to disambiguate the two definitions. You can either:
+  | To fix this error, you must disambiguate the two definitions by doing one of the following:
+  |
+  | 1. Rename one of the definitions. Provide an explicit, unique name to given definitions,
+  |    since the names assigned to anonymous givens may clash. For example:
+  |
+  |       given myGiven: [A] => Special[Option[A]]
   |
-  | 1. Rename one of the definitions, or
   | 2. Keep the same names in source but give one definition a distinct
   |    bytecode-level name via `@targetName`; for example:
   |
   |       @targetName("given_Special_Option_2")
   |       final given def given_Special_Option[A]: Special[Option[A]]
   |
-  | 3. Provide an explicit, unique name to given definitions, since the names
-  |    assigned to anonymous givens may clash. For example:
-  |
-  |       given myGiven: [A]: Special[Option[A]]
-  |
   | Choose the `@targetName` argument carefully: it is the name that will be used
   | when calling the method externally, so it should be unique and descriptive.
    ---------------------------------------------------------------------------------------------------------------------

Original file line number	Diff line number	Diff line change
`@@ -31,9 +31,9 @@`
`31`	`31`	`\|`
`32`	`32`	`\| so the compiler cannot keep both: the generated bytecode symbols would collide.`
`33`	`33`	`\|`
`34`		`- \| To fix this error, you need to disambiguate the two definitions. You can either:`
	`34`	`+ \| To fix this error, you must disambiguate the two definitions by doing one of the following:`
`35`	`35`	`\|`
`36`		`- \| 1. Rename one of the definitions, or`
	`36`	`+ \| 1. Rename one of the definitions.`
`37`	`37`	`\| 2. Keep the same names in source but give one definition a distinct`
`38`	`38`	\| bytecode-level name via `@targetName`; for example:
`39`	`39`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -27,20 +27,19 @@`
`27`	`27`	`\|`
`28`	`28`	`\| so the compiler cannot keep both: the generated bytecode symbols would collide.`
`29`	`29`	`\|`
`30`		`- \| To fix this error, you need to disambiguate the two definitions. You can either:`
	`30`	`+ \| To fix this error, you must disambiguate the two definitions by doing one of the following:`
	`31`	`+ \|`
	`32`	`+ \| 1. Rename one of the definitions. Provide an explicit, unique name to given definitions,`
	`33`	`+ \| since the names assigned to anonymous givens may clash. For example:`
	`34`	`+ \|`
	`35`	`+ \| given myGiven: Special[Option[Int]]`
`31`	`36`	`\|`
`32`		`- \| 1. Rename one of the definitions, or`
`33`	`37`	`\| 2. Keep the same names in source but give one definition a distinct`
`34`	`38`	\| bytecode-level name via `@targetName`; for example:
`35`	`39`	`\|`
`36`	`40`	`\| @targetName("given_Special_Option_2")`
`37`	`41`	`\| final lazy given val given_Special_Option: Special[Option[Int]]`
`38`	`42`	`\|`
`39`		`- \| 3. Provide an explicit, unique name to given definitions, since the names`
`40`		`- \| assigned to anonymous givens may clash. For example:`
`41`		`- \|`
`42`		`- \| given myGiven: Special[Option[Int]]`
`43`		`- \|`
`44`	`43`	\| Choose the `@targetName` argument carefully: it is the name that will be used
`45`	`44`	`\| when calling the method externally, so it should be unique and descriptive.`
`46`	`45`	`---------------------------------------------------------------------------------------------------------------------`