Turn off captureSetofInfo caching

Author: odersky

compiler/src/dotty/tools/dotc/cc/Capability.scala

@@ -495,7 +495,11 @@ object Capabilities:
         def isProvisional = this.core match
           case core: TypeProxy => !core.underlying.exists || core.underlying.isProvisional
           case _ => false
-        if !isCaptureChecking || ctx.mode.is(Mode.IgnoreCaptures) || isProvisional then
+        if !ccConfig.cacheCaptureSetOfInfo
+            || !isCaptureChecking
+            || ctx.mode.is(Mode.IgnoreCaptures)
+            || isProvisional
+        then
           myCaptureSet = null
         else
           myCaptureSet = computed

compiler/src/dotty/tools/dotc/cc/ccConfig.scala

@@ -7,6 +7,9 @@ import config.{Feature, SourceVersion}
 
 object ccConfig:
 
+  /** If enabled, cache capture sets of infos capabilties */
+  inline val cacheCaptureSetOfInfo = false
+
   /** If enabled, use a special path in recheckClosure for closures
    *  to compare the result tpt of the anonymous functon with the expected
    *  result type. This can narrow the scope of error messages.

tests/neg-custom-args/captures/reaches2.check

@@ -1,8 +1,12 @@
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/reaches2.scala:10:10 -------------------------------------
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/reaches2.scala:10:8 --------------------------------------
 10 |  ps.map((x, y) => compose1(x, y)) // error
-   |          ^^^^^^^^^^^^^^^^^^^^^^^
-   |          Found:    (x$1: (A^? ->{ps*} A^?, A^? ->{ps*} A^?)^?) ->{ps*} A^? ->{ps*} A^?
-   |          Required: ((A ->{ps*} A, A ->{ps*} A)) -> A^? ->? A^?
-   |          Note that capability ps* is not included in capture set {}.
+   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |  Found:    List[A^? ->{ps*, cap, cap²} A^?]
+   |  Required: List[A ->{ps*} A]
+   |
+   |  where:    cap  is a fresh root capability created in method mapCompose when computing deep capture set of A
+   |            cap² is a fresh root capability created in method mapCompose when computing deep capture set of A
+   |
+   |  Note that capability cap is not included in capture set {ps*}.
    |
    | longer explanation available when compiling with `-explain`