Fix codegen for structured binding binding in conditions

Summary:
The codegen for conditions assumes that a normal variable declaration is used in a condition, but this is not the case when a structured binding is used.

This fixes [PR36747](http://llvm.org/pr36747).

Thanks Nicolas Lesser for contributing the patch.

Reviewers: lichray, rsmith

Reviewed By: lichray

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D44534

llvm-svn: 327780

2 files changed, 35 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 86c0964a857..b1d1bf874dd 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -608,7 +608,7 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
     EmitStmt(S.getInit());
 
   if (S.getConditionVariable())
-    EmitAutoVarDecl(*S.getConditionVariable());
+    EmitDecl(*S.getConditionVariable());
 
   // If the condition constant folds and can be elided, try to avoid emitting
   // the condition and the dead arm of the if/else.
@@ -705,7 +705,7 @@ void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
   RunCleanupsScope ConditionScope(*this);
 
   if (S.getConditionVariable())
-    EmitAutoVarDecl(*S.getConditionVariable());
+    EmitDecl(*S.getConditionVariable());
 
   // Evaluate the conditional in the while header.  C99 6.8.5.1: The
   // evaluation of the controlling expression takes place before each
@@ -865,7 +865,7 @@ void CodeGenFunction::EmitForStmt(const ForStmt &S,
     // If the for statement has a condition scope, emit the local variable
     // declaration.
     if (S.getConditionVariable()) {
-      EmitAutoVarDecl(*S.getConditionVariable());
+      EmitDecl(*S.getConditionVariable());
     }
 
     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
@@ -1574,7 +1574,7 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
       // Emit the condition variable if needed inside the entire cleanup scope
       // used by this special case for constant folded switches.
       if (S.getConditionVariable())
-        EmitAutoVarDecl(*S.getConditionVariable());
+        EmitDecl(*S.getConditionVariable());
 
       // At this point, we are no longer "within" a switch instance, so
       // we can temporarily enforce this to ensure that any embedded case
@@ -1603,7 +1603,7 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
     EmitStmt(S.getInit());
 
   if (S.getConditionVariable())
-    EmitAutoVarDecl(*S.getConditionVariable());
+    EmitDecl(*S.getConditionVariable());
   llvm::Value *CondV = EmitScalarExpr(S.getCond());
 
   // Create basic block to hold stuff that comes after switch
diff --git a/clang/test/Parser/decomposed-condition.cpp b/clang/test/Parser/decomposed-condition.cpp
index c41c82292e8..4c635c4735d 100644
--- a/clang/test/Parser/decomposed-condition.cpp
+++ b/clang/test/Parser/decomposed-condition.cpp
@@ -1,5 +1,20 @@
 // RUN: %clang_cc1 -std=c++1z %s -verify
 
+namespace std {
+  template<typename> struct tuple_size;
+  template<int, typename> struct tuple_element;
+}
+
+struct Get {
+  template<int> int get() { return 0; }
+  operator bool() { return true; }
+};
+
+namespace std {
+  template<> struct tuple_size<Get> { static constexpr int value = 1; };
+  template<> struct tuple_element<0, Get> { using type = int; };
+}
+
 struct Na {
   bool flag;
   float data;
@@ -17,29 +32,35 @@ Rst f();
 Na g();
 
 namespace CondInIf {
-void h() {
+int h() {
   if (auto [ok, d] = f()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
     ;
   if (auto [ok, d] = g()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'Na' is not contextually convertible to 'bool'}}
     ;
+  if (auto [value] = Get()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
+    return value;
 }
 } // namespace CondInIf
 
 namespace CondInWhile {
-void h() {
+int h() {
   while (auto [ok, d] = f()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
     ;
   while (auto [ok, d] = g()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'Na' is not contextually convertible to 'bool'}}
     ;
+  while (auto [value] = Get()) // expected-warning{{ISO C++17 does not permit structured binding declaration in a condition}}
+    return value;
 }
 } // namespace CondInWhile
 
 namespace CondInFor {
-void h() {
+int h() {
   for (; auto [ok, d] = f();) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
     ;
   for (; auto [ok, d] = g();) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'Na' is not contextually convertible to 'bool'}}
     ;
+  for (; auto [value] = Get();) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
+    return value;
 }
 } // namespace CondInFor
 
@@ -52,10 +73,15 @@ struct IntegerLike {
 };
 
 namespace CondInSwitch {
-void h(IntegerLike x) {
+int h(IntegerLike x) {
   switch (auto [ok, d] = x) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
     ;
   switch (auto [ok, d] = g()) // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{statement requires expression of integer type ('Na' invalid)}}
     ;
+  switch (auto [value] = Get()) {// expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}}
+  // expected-warning@-1{{switch condition has boolean value}}
+  case 1:
+    return value;
+  }
 }
 } // namespace CondInSwitch