RequirementMachine: Add some tests for concrete type unification

Author: slavapestov

test/Generics/minimize_concrete_unification.swift

@@ -0,0 +1,173 @@
+// RUN: %target-swift-frontend -typecheck %s -debug-generic-signatures -requirement-machine-protocol-signatures=on 2>&1 | %FileCheck %s
+
+struct G<T> {}
+
+// Three requirements where any two imply the third:
+//
+// a) T == G<U>
+// b) T == G<Int>
+// c) U == Int
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pab@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pab]T == G<Int>, Self.[Pab]U == Int>
+
+protocol Pab {
+  associatedtype T where T == G<U>, T == G<Int>
+  associatedtype U
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pac@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pac]T == G<Int>, Self.[Pac]U == Int>
+
+protocol Pac {
+  associatedtype T where T == G<U>
+  associatedtype U where U == Int
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pbc@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pbc]T == G<Int>, Self.[Pbc]U == Int>
+
+protocol Pbc {
+  associatedtype T where T == G<Int>
+  associatedtype U where U == Int
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pabc@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pabc]T == G<Int>, Self.[Pabc]U == Int>
+
+protocol Pabc {
+  associatedtype T where T == G<U>, T == G<Int>
+  associatedtype U where U == Int
+}
+
+//
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pa@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pa]T == G<Self.[Pa]U>>
+
+protocol Pa {
+  associatedtype T where T == G<U>
+  associatedtype U
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PaQb@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PaQb]X : Pa, Self.[PaQb]X.[Pa]U == Int>
+
+protocol PaQb {
+  associatedtype X : Pa where X.T == G<Int>
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PaQc@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PaQc]X : Pa, Self.[PaQc]X.[Pa]U == Int>
+
+protocol PaQc {
+  associatedtype X : Pa where X.U == Int
+}
+
+//
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pb@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pb]T == G<Int>>
+
+protocol Pb {
+  associatedtype T where T == G<Int>
+  associatedtype U
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PbQa@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PbQa]X : Pb, Self.[PbQa]X.[Pb]U == Int>
+
+protocol PbQa {
+  associatedtype X : Pb where X.T == G<X.U>
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PbQc@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PbQc]X : Pb, Self.[PbQc]X.[Pb]U == Int>
+
+protocol PbQc {
+  associatedtype X : Pb where X.U == Int
+}
+
+//
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Pc@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Pc]U == Int>
+
+protocol Pc {
+  associatedtype T
+  associatedtype U where U == Int
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PcQa@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PcQa]X : Pc, Self.[PcQa]X.[Pc]T == G<Int>>
+
+protocol PcQa {
+  associatedtype X : Pc where X.T == G<X.U>
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).PcQb@
+// CHECK-NEXT: Requirement signature: <Self where Self.[PcQb]X : Pc, Self.[PcQb]X.[Pc]T == G<Int>>
+
+protocol PcQb {
+  associatedtype X : Pc where X.T == G<Int>
+}
+
+//
+
+// CHECK-LABEL: minimize_concrete_unification.(file).Q1@
+// CHECK-NEXT: Requirement signature: <Self where Self.[Q1]V : Pa, Self.[Q1]W == Self.[Q1]V.[Pa]U>
+
+protocol Q1 {
+  associatedtype V where V : Pa, V.T == G<W>
+  associatedtype W
+}
+
+//
+
+// CHECK-LABEL: minimize_concrete_unification.(file).P1@
+// CHECK-NEXT: Requirement signature: <Self where Self.[P1]T == G<Self.[P1]U>>
+
+protocol P1 {
+  associatedtype T
+  associatedtype U where T == G<U>
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).P2@
+// CHECK-NEXT: Requirement signature: <Self where Self.[P2]T == G<Int>>
+
+protocol P2 {
+  associatedtype T where T == G<Int>
+  associatedtype U
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).P@
+// CHECK-NEXT: Requirement signature: <Self>
+
+protocol P {
+  associatedtype T
+  associatedtype U
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).R1@
+// CHECK-NEXT: Requirement signature: <Self where Self.[R1]X : P, Self.[R1]X : Pa, Self.[R1]X.[P]U == Int>
+
+protocol R1 {
+  // The GSB would drop 'X.T == Int' from the minimal signature.
+  associatedtype X where X : P, X.T == G<Int>, X : Pa
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).R2@
+// CHECK-NEXT: Requirement signature: <Self where Self.[R2]X : P, Self.[R2]X : Pb, Self.[R2]X.[P]U == Int>
+
+protocol R2 {
+  // The GSB would drop 'X.T == Int' from the minimal signature.
+  associatedtype X where X : P, X.T == G<X.U>, X : Pb
+}
+
+// CHECK-LABEL: minimize_concrete_unification.(file).R3@
+// CHECK-NEXT: Requirement signature: <Self where Self.[R3]X : Pa, Self.[R3]X : Pb>
+
+protocol R3 {
+  // The GSB would include a redundant 'X.T == Int' in the minimal signature.
+  associatedtype X where X : Pa, X.T == G<Int>, X : Pb
+}