From 61ce47014b4f4e912ee0d49e2220ca1fe373d918 Mon Sep 17 00:00:00 2001
From: Bryan Chan <bryan.chan@ca.ibm.com>
Date: Mon, 30 May 2016 02:09:05 -0400
Subject: [PATCH 1/2] Case statements are not the only kind that require
 wildcard dispatches and have guard branches.

---
 lib/SILGen/SILGenPattern.cpp | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/lib/SILGen/SILGenPattern.cpp b/lib/SILGen/SILGenPattern.cpp
index db5a459d3492c..562756f58ba2e 100644
--- a/lib/SILGen/SILGenPattern.cpp
+++ b/lib/SILGen/SILGenPattern.cpp
@@ -1032,17 +1032,25 @@ void PatternMatchEmission::emitWildcardDispatch(ClauseMatrix &clauses,
   assert(!hasGuard || !clauses[row].isIrrefutable());
 
   auto stmt = clauses[row].getClientData<CaseStmt>();
-  ArrayRef<CaseLabelItem> labelItems = stmt->getCaseLabelItems();
-  bool hasMultipleItems = labelItems.size() > 1;
+  bool hasMultipleItems = false;
+  if (stmt->getKind() == StmtKind::Case) {
+    ArrayRef<CaseLabelItem> labelItems = stmt->getCaseLabelItems();
+    hasMultipleItems = labelItems.size() > 1;
+  }
   
   // Bind the rest of the patterns.
   bindIrrefutablePatterns(clauses[row], args, !hasGuard, hasMultipleItems);
 
   // Emit the guard branch, if it exists.
   if (guardExpr) {
-    SGF.usingImplicitVariablesForPattern(clauses[row].getCasePattern(), stmt, [&]{
-      this->emitGuardBranch(guardExpr, guardExpr, failure);
-    });
+    if (stmt->getKind() == StmtKind::Case) {
+      SGF.usingImplicitVariablesForPattern(clauses[row].getCasePattern(), stmt, [&]{
+        this->emitGuardBranch(guardExpr, guardExpr, failure);
+      });
+    } else {
+      assert(stmt->getKind() == StmtKind::Catch);
+      emitGuardBranch(guardExpr, guardExpr, failure);
+    }
   }
 
   // Enter the row.

From ac53a1ef45bfc974bb5d22496bf70871a16da87f Mon Sep 17 00:00:00 2001
From: Gary Liu <garyliu@ca.ibm.com>
Date: Wed, 22 Jun 2016 22:38:12 -0400
Subject: [PATCH 2/2] New test case to show the problem fixed by commit
 61ce47014b4f4e912ee0d49e2220ca1fe373d918

Fix new test case from commit fcaba99c81edcb8320856cb55367e1d8a9176675

Adding the review changes to #3193
---
 lib/SILGen/SILGenPattern.cpp                  | 28 ++++++++-------
 .../wildcard_dispatch_on_catch.swift          | 36 +++++++++++++++++++
 2 files changed, 51 insertions(+), 13 deletions(-)
 create mode 100644 test/Interpreter/wildcard_dispatch_on_catch.swift

diff --git a/lib/SILGen/SILGenPattern.cpp b/lib/SILGen/SILGenPattern.cpp
index 562756f58ba2e..b46f6a9bf97e7 100644
--- a/lib/SILGen/SILGenPattern.cpp
+++ b/lib/SILGen/SILGenPattern.cpp
@@ -1031,26 +1031,22 @@ void PatternMatchEmission::emitWildcardDispatch(ClauseMatrix &clauses,
   bool hasGuard = guardExpr != nullptr;
   assert(!hasGuard || !clauses[row].isIrrefutable());
 
-  auto stmt = clauses[row].getClientData<CaseStmt>();
+  auto stmt = clauses[row].getClientData<Stmt>();
+  assert(isa<CaseStmt>(stmt) || isa<CatchStmt>(stmt));
+
   bool hasMultipleItems = false;
-  if (stmt->getKind() == StmtKind::Case) {
-    ArrayRef<CaseLabelItem> labelItems = stmt->getCaseLabelItems();
-    hasMultipleItems = labelItems.size() > 1;
+  if (auto *caseStmt = dyn_cast<CaseStmt>(stmt)) {
+    hasMultipleItems = caseStmt->getCaseLabelItems().size() > 1;
   }
-  
+
   // Bind the rest of the patterns.
   bindIrrefutablePatterns(clauses[row], args, !hasGuard, hasMultipleItems);
 
   // Emit the guard branch, if it exists.
   if (guardExpr) {
-    if (stmt->getKind() == StmtKind::Case) {
-      SGF.usingImplicitVariablesForPattern(clauses[row].getCasePattern(), stmt, [&]{
-        this->emitGuardBranch(guardExpr, guardExpr, failure);
-      });
-    } else {
-      assert(stmt->getKind() == StmtKind::Catch);
-      emitGuardBranch(guardExpr, guardExpr, failure);
-    }
+    SGF.usingImplicitVariablesForPattern(clauses[row].getCasePattern(), dyn_cast<CaseStmt>(stmt), [&]{
+      this->emitGuardBranch(guardExpr, guardExpr, failure);
+    });
   }
 
   // Enter the row.
@@ -2190,6 +2186,12 @@ class Lowering::PatternMatchContext {
 
 void SILGenFunction::usingImplicitVariablesForPattern(Pattern *pattern, CaseStmt *stmt,
                                                       const llvm::function_ref<void(void)> &f) {
+  // Early exit for CatchStmt
+  if (!stmt) {
+    f();
+    return;
+  }
+
   ArrayRef<CaseLabelItem> labelItems = stmt->getCaseLabelItems();
   auto expectedPattern = labelItems[0].getPattern();
   
diff --git a/test/Interpreter/wildcard_dispatch_on_catch.swift b/test/Interpreter/wildcard_dispatch_on_catch.swift
new file mode 100644
index 0000000000000..ad8f434019d52
--- /dev/null
+++ b/test/Interpreter/wildcard_dispatch_on_catch.swift
@@ -0,0 +1,36 @@
+// RUN: rm -rf %t  &&  mkdir %t
+// RUN: %target-build-swift %s -o %t/a.out
+// RUN: %target-run %t/a.out | FileCheck %s
+// REQUIRES: executable_test
+
+enum testError: ErrorProtocol {
+  case C1
+  case C2(Int, String)
+}
+
+public func someFunc(_ str: String) throws -> String {
+  if (str[str.startIndex] == "D") {
+    throw testError.C2(2, str)
+  }
+  return str
+}
+
+let testData: [String] = [
+  "ABC",
+  "DEF",
+  ]
+
+public func testCatchWildcardDispatch(_ name: String...) throws {
+  for dir in testData {
+    do {
+      print(try someFunc(dir))
+    } catch .C2(let errno, _) as testError where errno == 2 {
+      print(name)
+    }
+  }
+}
+
+// CHECK: ABC
+// CHECK: ["TEST"]
+try testCatchWildcardDispatch("TEST")
+