Improve typer traces

1. Drop traceIndented from isSubType, which calls recur so it was just doubling the lines 2. Replace newlines with spaces, in doTrace and traceIndented, as they're meant to be single lines. For example ErrorType and MatchType have toText that are multi-line and mess up the output. 3. Change ExplainingTypeComparer#addConstraint to use show like the other methods.
scala · Jan 15, 2022 · 97b96b6 · 97b96b6
1 parent c01d596
commit 97b96b6
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Showing 3 changed files with 28 additions and 51 deletions.
diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -210,7 +210,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
    *  types (as when we go from an abstract type to one of its bounds). In that case
    *  one should use `isSubType(_, _, a)` where `a` defines the kind of approximation.
    *
-   *  Note: Logicaly, `recur` could be nested in `isSubType`, which would avoid
+   *  Note: Logically, `recur` could be nested in `isSubType`, which would avoid
    *  the instance state consisting `approx` and `leftRoot`. But then the implemented
    *  code would have two extra parameters for each of the many calls that go from
    *  one sub-part of isSubType to another.
@@ -2955,27 +2955,24 @@ class ExplainingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
     if (skipped) op
     else {
       indent += 2
-      b.append("\n").append(" " * indent).append("==> ").append(str)
+      val str1 = str.replace('\n', ' ')
+      b.append("\n").append(" " * indent).append("==> ").append(str1)
       val res = op
-      b.append("\n").append(" " * indent).append("<== ").append(str).append(" = ").append(show(res))
+      b.append("\n").append(" " * indent).append("<== ").append(str1).append(" = ").append(show(res))
       indent -= 2
       res
     }
 
   private def frozenNotice: String =
     if frozenConstraint then " in frozen constraint" else ""
 
-  override def isSubType(tp1: Type, tp2: Type, approx: ApproxState): Boolean =
+  override def recur(tp1: Type, tp2: Type): Boolean =
     def moreInfo =
       if Config.verboseExplainSubtype || ctx.settings.verbose.value
       then s" ${tp1.getClass} ${tp2.getClass}"
       else ""
+    val approx = approxState
     traceIndented(s"${show(tp1)}  <:  ${show(tp2)}$moreInfo${approx.show}$frozenNotice") {
-      super.isSubType(tp1, tp2, approx)
-    }
-
-  override def recur(tp1: Type, tp2: Type): Boolean =
-    traceIndented(s"${show(tp1)}  <:  ${show(tp2)} (recurring)$frozenNotice") {
       super.recur(tp1, tp2)
     }
 
@@ -2995,7 +2992,7 @@ class ExplainingTypeComparer(initctx: Context) extends TypeComparer(initctx) {
     }
 
   override def addConstraint(param: TypeParamRef, bound: Type, fromBelow: Boolean)(using Context): Boolean =
-    traceIndented(i"add constraint $param ${if (fromBelow) ">:" else "<:"} $bound $frozenConstraint, constraint = ${ctx.typerState.constraint}") {
+    traceIndented(s"add constraint ${show(param)} ${if (fromBelow) ">:" else "<:"} ${show(bound)} $frozenNotice, constraint = ${show(ctx.typerState.constraint)}") {
       super.addConstraint(param, bound, fromBelow)
     }
 

diff --git a/compiler/src/dotty/tools/dotc/reporting/trace.scala b/compiler/src/dotty/tools/dotc/reporting/trace.scala
@@ -76,7 +76,7 @@ trait TraceSyntax:
     else
       // Avoid evaluating question multiple time, since each evaluation
       // may cause some extra logging output.
-      val q = question
+      val q = question.replace('\n', ' ')
       val leading = s"==> $q?"
       val trailing = (res: T) => s"<== $q = ${showOp(res)}"
       var finalized = false

diff --git a/tests/neg-custom-args/i11637.check b/tests/neg-custom-args/i11637.check
@@ -13,26 +13,16 @@ conforms to
 but the comparison trace ended with `false`:
 
   ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
-    ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any (recurring)
-      ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]]
-        ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] (recurring)
-          ==> [T <: String] =>> Set[T]  <:  Iterable
-            ==> [T <: String] =>> Set[T]  <:  Iterable (recurring)
-              ==> type bounds []  <:  type bounds [ <: String]
-                ==> type bounds []  <:  type bounds [ <: String] (recurring)
-                  ==> Any  <:  String
-                    ==> Any  <:  String (recurring)
-                      ==> Any  <:  String (recurring)
-                      <== Any  <:  String (recurring) = false
-                    <== Any  <:  String (recurring) = false
-                  <== Any  <:  String = false
-                <== type bounds []  <:  type bounds [ <: String] (recurring) = false
-              <== type bounds []  <:  type bounds [ <: String] = false
-            <== [T <: String] =>> Set[T]  <:  Iterable (recurring) = false
-          <== [T <: String] =>> Set[T]  <:  Iterable = false
-        <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] (recurring) = false
-      <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] = false
-    <== test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any (recurring) = false
+    ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]]
+      ==> [T <: String] =>> Set[T]  <:  Iterable
+        ==> type bounds []  <:  type bounds [ <: String]
+          ==> Any  <:  String
+            ==> Any  <:  String
+            <== Any  <:  String = false
+          <== Any  <:  String = false
+        <== type bounds []  <:  type bounds [ <: String] = false
+      <== [T <: String] =>> Set[T]  <:  Iterable = false
+    <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] = false
   <== test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any = false
 
 The tests were made under the empty constraint
@@ -52,26 +42,16 @@ conforms to
 but the comparison trace ended with `false`:
 
   ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
-    ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any (recurring)
-      ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]]
-        ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] (recurring)
-          ==> [T <: String] =>> Set[T]  <:  Iterable
-            ==> [T <: String] =>> Set[T]  <:  Iterable (recurring)
-              ==> type bounds []  <:  type bounds [ <: String]
-                ==> type bounds []  <:  type bounds [ <: String] (recurring)
-                  ==> Any  <:  String
-                    ==> Any  <:  String (recurring)
-                      ==> Any  <:  String (recurring)
-                      <== Any  <:  String (recurring) = false
-                    <== Any  <:  String (recurring) = false
-                  <== Any  <:  String = false
-                <== type bounds []  <:  type bounds [ <: String] (recurring) = false
-              <== type bounds []  <:  type bounds [ <: String] = false
-            <== [T <: String] =>> Set[T]  <:  Iterable (recurring) = false
-          <== [T <: String] =>> Set[T]  <:  Iterable = false
-        <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] (recurring) = false
-      <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] = false
-    <== test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any (recurring) = false
+    ==> type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]]
+      ==> [T <: String] =>> Set[T]  <:  Iterable
+        ==> type bounds []  <:  type bounds [ <: String]
+          ==> Any  <:  String
+            ==> Any  <:  String
+            <== Any  <:  String = false
+          <== Any  <:  String = false
+        <== type bounds []  <:  type bounds [ <: String] = false
+      <== [T <: String] =>> Set[T]  <:  Iterable = false
+    <== type bounds [[T <: String] <: Set[T]]  <:  type bounds [[T] <: Iterable[T]] = false
   <== test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any = false
 
 The tests were made under the empty constraint