Add more test cases

Author: calda

include/swift/Sema/ConstraintSystem.h

@@ -1966,6 +1966,9 @@ enum class ConstraintSystemFlags {
 
   /// Enable old type-checker performance hacks.
   EnablePerformanceHacks = 0x80,
+
+  /// Don't record a failed constraint after adding an unsolvable constraint.
+  DisableRecordFailedConstraint = 0x100,
 };
 
 /// Options that affect the constraint system as a whole.
@@ -3824,6 +3827,9 @@ class ConstraintSystem {
 
   /// Whether we should record the failure of a constraint.
   bool shouldRecordFailedConstraint() const {
+    if (Options.contains(ConstraintSystemFlags::DisableRecordFailedConstraint))
+      return false;
+
     // If we're debugging, always note a failure so we can print it out.
     if (isDebugMode())
       return true;

lib/Sema/TypeCheckType.cpp

@@ -7022,11 +7022,16 @@ struct ResultBuilderUnboundTypeOpener {
 
     auto genericSig = resultBuilderDecl->getGenericSignature();
 
-    // Try each result type and return the first one that produces a valid
-    // solution
+    // Try each result type and return the first one that
+    // produces a valid solution.
     for (auto componentType : resultTypes) {
       using namespace constraints;
-      ConstraintSystem cs(dc, std::nullopt);
+
+      // Avoid recording failed constraints, which are not used here.
+      ConstraintSystemOptions options;
+      options |= ConstraintSystemFlags::DisableRecordFailedConstraint;
+
+      ConstraintSystem cs(dc, options);
 
       // Create a type variable for each of the result builder's generic params
       llvm::SmallVector<Type, 8> typeVarReplacements;

test/Constraints/result_builder_diags.swift

@@ -1080,14 +1080,29 @@ func testNoDuplicateStmtDiags() {
   }
 }
 
-func testInferResultBuilderGenerics() {
-  @resultBuilder
-  struct SimpleArrayBuilder<Element> {
-    static func buildBlock(_ elements: Element...) -> [Element] {
-      elements
-    }
+@resultBuilder
+enum SimpleArrayBuilder<ElementKind> {
+  static func buildBlock(_ elements: ElementKind...) -> [ElementKind] {
+    elements
   }
+}
+
+@resultBuilder
+enum CollectionBuilder<Element> {
+    static func buildBlock(_ component: Element...) -> [Element] {
+      component
+    }
 
+    static func buildFinalResult(_ component: [Element]) -> [Element] {
+        component
+    }
+
+    static func buildFinalResult(_ component: [Element]) -> Set<Element> where Element: Hashable {
+        Set(component)
+    }
+}
+
+func testInferResultBuilderGenerics() {
   @SimpleArrayBuilder
   var stringArray: [String] {
     "foo"
@@ -1157,7 +1172,7 @@ func testInferResultBuilderGenerics() {
     ("foo", 1) // expected-warning {{expression of type '(String, Int)' is unused}}
     ("bar", 2) // expected-warning {{expression of type '(String, Int)' is unused}}
   }
-  
+
   @resultBuilder
   enum ComplexListBuilder<Element> {
     static func buildBlock(_ elements: Element...) -> [Element] {
@@ -1207,4 +1222,54 @@ func testInferResultBuilderGenerics() {
     "foo"
     "bar"
   }
+
+  @CollectionBuilder
+  var array: [String] {
+      "a"
+      "b"
+  }
+
+  @CollectionBuilder
+  var set: Set<String> {
+      "c"
+      "d"
+  }
+  
+  @CollectionBuilder // expected-error {{unable to infer generic parameters for result builder 'CollectionBuilder'}}
+  var contiguousArray: ContiguousArray<String> {
+      "c" // expected-warning {{string literal is unused}}
+      "d" // expected-warning {{string literal is unused}}
+  }
+}
+
+extension Array {
+  init(@SimpleArrayBuilder build1: () -> Self) {
+    self = build1()
+  }
+  
+  init(@SimpleArrayBuilder build2: () -> [Element]) {
+      self = build2()
+  }
+  
+  init(@SimpleArrayBuilder build3: () -> Array<Self.Element>) {
+      self = build3()
+  }
+  
+  init(@SimpleArrayBuilder build3: () -> ContiguousArray<Element>) { // expected-error {{unable to infer generic parameters for result builder 'SimpleArrayBuilder'}}
+      self = Array(build3())
+  }
+}
+
+extension Set {
+  init(@CollectionBuilder build: () -> Self) {
+    self = build()
+  }
+  
+  init(@CollectionBuilder build2: () -> [Element]) {
+    self = Set(build2())
+  }
+  
+  init(@SimpleArrayBuilder build3: () -> Self) { // expected-error {{unable to infer generic parameters for result builder 'SimpleArrayBuilder'}}
+    self = build3()
+  }
 }