From f205f469a983de289fbfd6750234241d25e37cb9 Mon Sep 17 00:00:00 2001
From: Hamish Knight <hamish_knight@apple.com>
Date: Wed, 5 Nov 2025 20:29:15 +0000
Subject: [PATCH] [CS] Replace error type with hole for projected value

Missed this in my previous patch, make sure we replace an error with
a hole if necessary.
---
 lib/Sema/CSSyntacticElement.cpp                       |  5 +++++
 .../ConstraintSystem-applySolution-bbfc02.swift       | 11 +++++++++++
 .../ConstraintSystem-applySolution-082642.swift       | 10 ++++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 validation-test/IDE/crashers_fixed/ConstraintSystem-applySolution-bbfc02.swift
 create mode 100644 validation-test/compiler_crashers_fixed/ConstraintSystem-applySolution-082642.swift

diff --git a/lib/Sema/CSSyntacticElement.cpp b/lib/Sema/CSSyntacticElement.cpp
index bc2b064ca07ee..e90859f7805ba 100644
--- a/lib/Sema/CSSyntacticElement.cpp
+++ b/lib/Sema/CSSyntacticElement.cpp
@@ -801,6 +801,11 @@ class SyntacticElementConstraintGenerator
     auto wrapperTy = cs.simplifyType(cs.getType(wrapperTypeExpr));
     if (auto *projectedVal = wrappedVar->getPropertyWrapperProjectionVar()) {
       auto projectedTy = computeProjectedValueType(wrappedVar, wrapperTy);
+      // The projected type may have an error, make sure we turn it into a hole
+      // if necessary.
+      ASSERT(!projectedTy->hasUnboundGenericType() &&
+             !projectedTy->hasPlaceholder());
+      projectedTy = cs.replaceInferableTypesWithTypeVars(projectedTy, locator);
       cs.setType(projectedVal, projectedTy);
     }
     if (auto *backing = wrappedVar->getPropertyWrapperBackingProperty())
diff --git a/validation-test/IDE/crashers_fixed/ConstraintSystem-applySolution-bbfc02.swift b/validation-test/IDE/crashers_fixed/ConstraintSystem-applySolution-bbfc02.swift
new file mode 100644
index 0000000000000..5bec87c9dee3c
--- /dev/null
+++ b/validation-test/IDE/crashers_fixed/ConstraintSystem-applySolution-bbfc02.swift
@@ -0,0 +1,11 @@
+// {"kind":"complete","original":"3da7ab26","signature":"swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::constraints::SyntacticElementTarget)","signatureAssert":"Assertion failed: (isValidType(solution.simplifyType(type)) && \"node type has invalid type\"), function applySolution"}
+// RUN: %target-swift-ide-test -code-completion -batch-code-completion -skip-filecheck -code-completion-diagnostics -source-filename %s
+@propertyWrapper struct a<b {
+  init(wrappedValue: b)
+projectedValue:
+  var wrappedValue: b
+}
+{
+  @a var c = false
+  switch c {
+    #^^#
diff --git a/validation-test/compiler_crashers_fixed/ConstraintSystem-applySolution-082642.swift b/validation-test/compiler_crashers_fixed/ConstraintSystem-applySolution-082642.swift
new file mode 100644
index 0000000000000..e0f76823bd391
--- /dev/null
+++ b/validation-test/compiler_crashers_fixed/ConstraintSystem-applySolution-082642.swift
@@ -0,0 +1,10 @@
+// {"kind":"typecheck","signature":"swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::constraints::SyntacticElementTarget)","signatureAssert":"Assertion failed: (isValidType(solution.simplifyType(type)) && \"node type has invalid type\"), function applySolution"}
+// RUN: not %target-swift-frontend -typecheck %s
+@propertyWrapper struct a<b > {
+  init(wrappedValue: b)
+projectedValue:
+  var wrappedValue: b
+}
+{
+  @a var c = false
+}