Backport "Space: Replace showType & make Space Showable" to LTS (#20816)

Backports #19370 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

compiler/test/dotty/tools/dotc/transform/patmat/SpaceEngineTest.scala

@@ -27,12 +27,12 @@ class SpaceEngineTest:
     val a = Prod(tp, unappTp, params)
     val b = Empty
 
-    val res1 = isSubspace(a, b)
+    val res1 = a.isSubspace(b)
 
-    val a2   = simplify(a)
-    val b2   = simplify(b)
+    val a2   = a.simplify
+    val b2   = b.simplify
     val rem1 = minus(a2, b2)
-    val rem2 = simplify(rem1)
+    val rem2 = rem1.simplify
     val res2 = rem2 == Empty
 
     assertEquals(
@@ -46,19 +46,12 @@ class SpaceEngineTest:
           |simplify(rem1)                      == Empty
           |rem2                                == Empty
           |
-          |a    = ${show(a)}
-          |b    = ${show(b)}
-          |a2   = ${show(a2)}
-          |b2   = ${show(b2)}
-          |rem1 = ${show(rem1)}
-          |rem2 = ${show(rem2)}
-          |
-          |a    = ${a.toString}
-          |b    = ${b.toString}
-          |a2   = ${a2.toString}
-          |b2   = ${b2.toString}
-          |rem1 = ${rem1.toString}
-          |rem2 = ${rem2.toString}
+          |a    = $a
+          |b    = $b
+          |a2   = $a2
+          |b2   = $b2
+          |rem1 = $rem1
+          |rem2 = $rem2
           |
           |""".stripMargin, res1, res2)
   }

tests/patmat/aliasing.check

@@ -1,3 +1,3 @@
-14: Pattern Match Exhaustivity: _: Trait & Test.Alias1, _: Clazz & Test.Alias1
-19: Pattern Match Exhaustivity: _: Trait & Test.Alias2
-23: Pattern Match Exhaustivity: _: Trait & (Test.Alias2 & OpenTrait2){val x: Int}
+14: Pattern Match Exhaustivity: _: Trait & Alias1, _: Clazz & Alias1
+19: Pattern Match Exhaustivity: _: Trait & Alias2
+23: Pattern Match Exhaustivity: _: Trait & (Alias2 & OpenTrait2){val x: Int}

tests/patmat/i12020.check

@@ -1 +1 @@
-19: Pattern Match Exhaustivity: _: TypeDef
+19: Pattern Match Exhaustivity: _: x$1.reflect.TypeDef

tests/patmat/i2502.check

@@ -1 +1 @@
-5: Pattern Match Exhaustivity: _: BTypes.ClassBType
+5: Pattern Match Exhaustivity: _: BTypes.this.ClassBType

tests/patmat/i2502b.check

@@ -1 +1 @@
-5: Pattern Match Exhaustivity: _: BTypes.ClassBType
+5: Pattern Match Exhaustivity: _: BTypes.this.ClassBType

tests/patmat/i3938.check

@@ -1 +1 @@
-34: Pattern Match Exhaustivity: bar.C()
+34: Pattern Match Exhaustivity: foo.bar.C()

tests/patmat/i6255b.check

@@ -1 +1 @@
-3: Pattern Match Exhaustivity: _: Expr[Int]
+3: Pattern Match Exhaustivity: _: scala.quoted.Expr[Int]

tests/patmat/t10100.check

@@ -1 +1 @@
-12: Pattern Match Exhaustivity: (_, FancyFoo(_))
+12: Pattern Match Exhaustivity: (_, NonExhaustive#FancyFoo(_))

tests/patmat/t9779.check

@@ -1 +1 @@
-10: Pattern Match Exhaustivity: _: a.Elem[_]
+10: Pattern Match Exhaustivity: _: a.Elem[?]