RequirementMachine: Skip emitting diagnostics containing ErrorTypes

Author: slavapestov

lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -725,16 +725,25 @@ bool swift::rewriting::diagnoseRequirementErrors(
       auto requirement = error.requirement;
       auto conflict = error.conflictingRequirement;
 
+      if (requirement.getFirstType()->hasError() ||
+          (requirement.getKind() != RequirementKind::Layout &&
+           requirement.getSecondType()->hasError())) {
+        // Don't emit a cascading error.
+        break;
+      }
+
       if (!conflict) {
-        if (requirement.getFirstType()->hasError() ||
-            requirement.getSecondType()->hasError()) {
-          // Don't emit a cascading error.
-          break;
-        }
         ctx.Diags.diagnose(loc, diag::requires_same_concrete_type,
                            requirement.getFirstType(),
                            requirement.getSecondType());
       } else {
+        if (conflict->getFirstType()->hasError() ||
+            (conflict->getKind() != RequirementKind::Layout &&
+             conflict->getSecondType()->hasError())) {
+          // Don't emit a cascading error.
+          break;
+        }
+
         auto options = PrintOptions::forDiagnosticArguments();
         std::string requirements;
         llvm::raw_string_ostream OS(requirements);
@@ -754,6 +763,13 @@ bool swift::rewriting::diagnoseRequirementErrors(
 
     case RequirementError::Kind::RedundantRequirement: {
       auto requirement = error.requirement;
+      if (requirement.getFirstType()->hasError() ||
+          (requirement.getKind() != RequirementKind::Layout &&
+           requirement.getSecondType()->hasError())) {
+        // Don't emit a cascading error.
+        break;
+      }
+
       switch (requirement.getKind()) {
       case RequirementKind::SameType:
         ctx.Diags.diagnose(loc, diag::redundant_same_type_to_concrete,

test/Generics/invalid.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
 
 protocol he where A : B { // expected-error {{cannot find type 'A' in scope}}
   // expected-error@-1 {{cannot find type 'B' in scope}}

test/decl/protocol/req/associated_type_inference.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
 
 protocol P0 {
   associatedtype Assoc1 : PSimple // expected-note{{ambiguous inference of associated type 'Assoc1': 'Double' vs. 'Int'}}

validation-test/compiler_crashers_2_fixed/0159-rdar40009245.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
 
 protocol P {
     associatedtype A : P where A.X == Self

validation-test/compiler_crashers_2_fixed/0161-sr6569.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
 
 protocol P {
     associatedtype A: P // expected-note {{protocol requires nested type 'A'; do you want to add it?}}