Improve -explain rendering

scala · Jan 27, 2022 · d24684b · d24684b
1 parent e523c8d
commit d24684b
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Showing 71 changed files with 459 additions and 320 deletions.
diff --git a/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/compiler/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -32,10 +32,6 @@ object ConsoleReporter {
     /** Prints the message with the given position indication. */
     def doReport(dia: Diagnostic)(using Context): Unit = {
       printMessage(messageAndPos(dia))
-      if Diagnostic.shouldExplain(dia) then
-        printMessage(explanation(dia.msg))
-      else if dia.msg.canExplain then
-        printMessage("\nlonger explanation available when compiling with `-explain`")
     }
   }
 }
diff --git a/compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala b/compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala
@@ -248,6 +248,20 @@ trait MessageRendering {
     else sb.append(msg.message)
     if (dia.isVerbose)
       appendFilterHelp(dia, sb)
+
+    if Diagnostic.shouldExplain(dia) then
+      sb.append(EOL).append(newBox())
+      sb.append(EOL).append(offsetBox).append(" Explanation")
+      sb.append(EOL).append(newBox(soft = true))
+      dia.msg.explanation.split(EOL).foreach { line =>
+        sb.append(EOL).append(offsetBox).append(if line.isEmpty then "" else " ").append(line)
+      }
+      sb.append(EOL).append(endBox)
+    else if dia.msg.canExplain then
+      sb.append(EOL).append(newBox())
+      sb.append(EOL).append(offsetBox).append(" longer explanation available when compiling with `-explain`")
+      sb.append(EOL).append(endBox)
+
     sb.toString
   }
 

diff --git a/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala b/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -142,18 +142,17 @@ object ErrorReporting {
           |conforms to
           |  $expected
           |but the comparison trace ended with `false`:
-          """
+          |"""
       val c = ctx.typerState.constraint
       val constraintText =
         if c.domainLambdas.isEmpty then
           "the empty constraint"
         else
           i"""a constraint with:
              |$c"""
-      i"""
-        |${TypeComparer.explained(_.isSubType(found, expected), header)}
-        |
-        |The tests were made under $constraintText"""
+      i"""${TypeComparer.explained(_.isSubType(found, expected), header)}
+         |
+         |The tests were made under $constraintText"""
 
     /** Format `raw` implicitNotFound or implicitAmbiguous argument, replacing
      *  all occurrences of `${X}` where `X` is in `paramNames` with the

diff --git a/tests/neg-custom-args/explicit-nulls/byname-nullables.check b/tests/neg-custom-args/explicit-nulls/byname-nullables.check
@@ -3,8 +3,9 @@
    |                        ^
    |                        Found:    (x : String | Null)
    |                        Required: String
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- Error: tests/neg-custom-args/explicit-nulls/byname-nullables.scala:43:32 --------------------------------------------
 43 |    if x != null then f(identity(x), 1)   // error: dropping not null check fails typing
    |                        ^^^^^^^^^^^

diff --git a/tests/neg-custom-args/explicit-nulls/i7883.check b/tests/neg-custom-args/explicit-nulls/i7883.check
@@ -10,11 +10,13 @@
 6 |      case r(hd, tl) => Some((hd, tl))  // error // error // error
   |                              ^^
   |                              Not found: hd
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
 -- [E006] Not Found Error: tests/neg-custom-args/explicit-nulls/i7883.scala:6:34 ---------------------------------------
 6 |      case r(hd, tl) => Some((hd, tl))  // error // error // error
   |                                  ^^
   |                                  Not found: tl
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/i11637.check b/tests/neg-custom-args/i11637.check
@@ -2,56 +2,55 @@
 11 |  var h = new HKT3_1[FunctorImpl]();  // error // error
    |                                 ^
    |       Type argument test2.FunctorImpl does not conform to upper bound [Generic2[T <: String] <: Set[T]] =>> Any
-
-Explanation
-===========
-
-I tried to show that
-  test2.FunctorImpl
-conforms to
-  [Generic2[T <: String] <: Set[T]] =>> Any
-but the comparison trace ended with `false`:
-
-  ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
-    ==> 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
-
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation
+   |····················································································································
+   | I tried to show that
+   |   test2.FunctorImpl
+   | conforms to
+   |   [Generic2[T <: String] <: Set[T]] =>> Any
+   | but the comparison trace ended with `false`:
+   |
+   |   ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
+   |     ==> 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
+   ·--------------------------------------------------------------------------------------------------------------------
 -- [E057] Type Mismatch Error: tests/neg-custom-args/i11637.scala:11:21 ------------------------------------------------
 11 |  var h = new HKT3_1[FunctorImpl]();  // error // error
    |                     ^
    |       Type argument test2.FunctorImpl does not conform to upper bound [Generic2[T <: String] <: Set[T]] =>> Any
-
-Explanation
-===========
-
-I tried to show that
-  test2.FunctorImpl
-conforms to
-  [Generic2[T <: String] <: Set[T]] =>> Any
-but the comparison trace ended with `false`:
-          
-  ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
-    ==> 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
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation
+   |····················································································································
+   | I tried to show that
+   |   test2.FunctorImpl
+   | conforms to
+   |   [Generic2[T <: String] <: Set[T]] =>> Any
+   | but the comparison trace ended with `false`:
+   |
+   |   ==> test2.FunctorImpl  <:  [Generic2[T <: String] <: Set[T]] =>> Any
+   |     ==> 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
+   ·--------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/i13026.check b/tests/neg-custom-args/i13026.check
@@ -3,15 +3,17 @@
   |             ^^^^^^^^^^^^
   |             Found:    ("not an int" : String)
   |             Required: Int
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
 -- [E007] Type Mismatch Error: tests/neg-custom-args/i13026.scala:2:13 -------------------------------------------------
 2 |val y: Int = "not an int" // error
   |             ^^^^^^^^^^^^
   |             Found:    ("not an int" : String)
   |             Required: Int
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
 -- [E008] Not Found Error: tests/neg-custom-args/i13026.scala:3:20 -----------------------------------------------------
 3 |def foo(x: Any) = x.foo // error
   |                  ^^^^^

diff --git a/tests/neg-custom-args/i13838.check b/tests/neg-custom-args/i13838.check
@@ -22,5 +22,6 @@
    |     You can change the behavior by setting the `-Ximplicit-search-limit` value.
    |     Smaller values cause the search to fail faster.
    |     Larger values might make a very large search problem succeed.
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/jdk-9-app.check b/tests/neg-custom-args/jdk-9-app.check
@@ -2,5 +2,6 @@
 4 |  println(ProcessHandle.current().pid()) // error: not found
   |          ^^^^^^^^^^^^^
   |          Not found: ProcessHandle
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/kind-projector-underscores.check b/tests/neg-custom-args/kind-projector-underscores.check
@@ -6,14 +6,16 @@
 10 |  type -_ = Int // error -_ not allowed as a type def name without backticks
    |        ^
    |        =, >:, or <: expected, but '_' found
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- [E095] Syntax Error: tests/neg-custom-args/kind-projector-underscores.scala:11:8 ------------------------------------
 11 |  type +_ = Int // error +_ not allowed as a type def name without backticks
    |        ^
    |        =, >:, or <: expected, but '_' found
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- Error: tests/neg-custom-args/kind-projector-underscores.scala:14:51 -------------------------------------------------
 14 |class BacktickUnderscoreIsNotFine extends Foo[List[`_`]] // error wildcard invalid as backquoted identifier
    |                                                   ^

diff --git a/tests/neg-custom-args/nowarn/nowarn-parser-error.check b/tests/neg-custom-args/nowarn/nowarn-parser-error.check
@@ -2,12 +2,14 @@
 3 |  def def // error
   |      ^^^
   |      an identifier expected, but 'def' found
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
 -- [E000] Syntax Warning: tests/neg-custom-args/nowarn/nowarn-parser-error.scala:2:10 ----------------------------------
 2 |  def a = try 1 // warn
   |          ^^^^^
   |          A try without catch or finally is equivalent to putting
   |          its body in a block; no exceptions are handled.
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/nowarn/nowarn-typer-error.check b/tests/neg-custom-args/nowarn/nowarn-typer-error.check
@@ -2,5 +2,6 @@
 4 |  def t1 = / // error
   |           ^
   |           Not found: /
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-custom-args/nowarn/nowarn.check b/tests/neg-custom-args/nowarn/nowarn.check
@@ -3,22 +3,25 @@
   |          ^^^^^
   |          A try without catch or finally is equivalent to putting
   |          its body in a block; no exceptions are handled.
-
-longer explanation available when compiling with `-explain`
+  |---------------------------------------------------------------------------------------------------------------------
+  | longer explanation available when compiling with `-explain`
+  ·---------------------------------------------------------------------------------------------------------------------
 -- [E000] Syntax Warning: tests/neg-custom-args/nowarn/nowarn.scala:23:25 ----------------------------------------------
 23 |@nowarn(o.inl) def t2d = try 1   // two warnings (`inl` is not a compile-time constant)
    |                         ^^^^^
    |                         A try without catch or finally is equivalent to putting
    |                         its body in a block; no exceptions are handled.
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- [E000] Syntax Warning: tests/neg-custom-args/nowarn/nowarn.scala:31:26 ----------------------------------------------
 31 |@nowarn("id=1") def t4d = try 1 // error and warning (unused nowarn, wrong id)
    |                          ^^^^^
    |                          A try without catch or finally is equivalent to putting
    |                          its body in a block; no exceptions are handled.
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- [E000] Syntax Warning: tests/neg-custom-args/nowarn/nowarn.scala:33:28 ----------------------------------------------
 33 |@nowarn("verbose") def t5 = try 1 // warning with details
    |                            ^^^^^
@@ -27,14 +30,16 @@ longer explanation available when compiling with `-explain`
 Matching filters for @nowarn or -Wconf:
   - id=E0
   - name=EmptyCatchOrFinallyBlock
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- [E129] Potential Issue Warning: tests/neg-custom-args/nowarn/nowarn.scala:13:11 -------------------------------------
 13 |def t2 = { 1; 2 } // warning (the invalid nowarn doesn't silence anything)
    |           ^
    |           A pure expression does nothing in statement position; you may be omitting necessary parentheses
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- Warning: tests/neg-custom-args/nowarn/nowarn.scala:12:8 -------------------------------------------------------------
 12 |@nowarn("wat?") // warning (typer, invalid filter)
    |        ^^^^^^
@@ -44,8 +49,9 @@ longer explanation available when compiling with `-explain`
 16 |def t2a = { 1; 2 } // warning (invalid nowarn doesn't silence)
    |            ^
    |            A pure expression does nothing in statement position; you may be omitting necessary parentheses
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------
 -- Warning: tests/neg-custom-args/nowarn/nowarn.scala:15:8 -------------------------------------------------------------
 15 |@nowarn(t1a.toString) // warning (typer, argument not a compile-time constant)
    |        ^^^^^^^^^^^^

diff --git a/tests/neg-macros/beta-reduce-inline-result.check b/tests/neg-macros/beta-reduce-inline-result.check
@@ -4,5 +4,6 @@
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                Found:    Int
    |                Required: (4 : Int)
-
-longer explanation available when compiling with `-explain`
+   |--------------------------------------------------------------------------------------------------------------------
+   | longer explanation available when compiling with `-explain`
+   ·--------------------------------------------------------------------------------------------------------------------