5 files changed, 40 insertions, 8 deletions

diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 7b9f8afafb1..adae6272237 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -1705,6 +1705,7 @@ private:
     DSC_top_level, // top-level/namespace declaration context
     DSC_template_type_arg, // template type argument context
     DSC_objc_method_result, // ObjC method result context, enables 'instancetype'
+    DSC_condition // condition declaration context
   };
 
   /// Is this a context in which we are parsing just a type-specifier (or
@@ -1715,6 +1716,7 @@ private:
     case DSC_class:
     case DSC_top_level:
     case DSC_objc_method_result:
+    case DSC_condition:
       return false;
 
     case DSC_template_type_arg:
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index e3294eca46f..f497c59cec1 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2173,7 +2173,7 @@ void Parser::ParseSpecifierQualifierList(DeclSpec &DS, AccessSpecifier AS,
   }
 
   // Issue diagnostic and remove constexpr specfier if present.
-  if (DS.isConstexprSpecified()) {
+  if (DS.isConstexprSpecified() && DSC != DSC_condition) {
     Diag(DS.getConstexprSpecLoc(), diag::err_typename_invalid_constexpr);
     DS.ClearConstexprSpec();
   }
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 7fb4b5e5a07..02176c41059 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -1686,7 +1686,7 @@ bool Parser::ParseCXXCondition(ExprResult &ExprOut,
   // type-specifier-seq
   DeclSpec DS(AttrFactory);
   DS.takeAttributesFrom(attrs);
-  ParseSpecifierQualifierList(DS);
+  ParseSpecifierQualifierList(DS, AS_none, DSC_condition);
 
   // declarator
   Declarator DeclaratorInfo(DS, Declarator::ConditionContext);
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 50e4345216a..6fca974d5b3 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -495,6 +495,7 @@ Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal, Decl *CondVar,
   if (CondVar) {
     ConditionVar = cast<VarDecl>(CondVar);
     CondResult = CheckConditionVariable(ConditionVar, IfLoc, true);
+    CondResult = ActOnFinishFullExpr(CondResult.get(), IfLoc);
     if (CondResult.isInvalid())
       return StmtError();
   }
@@ -649,12 +650,10 @@ Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, Expr *Cond,
   if (CondResult.isInvalid()) return StmtError();
   Cond = CondResult.get();
 
-  if (!CondVar) {
-    CondResult = ActOnFinishFullExpr(Cond, SwitchLoc);
-    if (CondResult.isInvalid())
-      return StmtError();
-    Cond = CondResult.get();
-  }
+  CondResult = ActOnFinishFullExpr(Cond, SwitchLoc);
+  if (CondResult.isInvalid())
+    return StmtError();
+  Cond = CondResult.get();
 
   getCurFunction()->setHasBranchIntoScope();
 
@@ -1229,6 +1228,7 @@ Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
   if (CondVar) {
     ConditionVar = cast<VarDecl>(CondVar);
     CondResult = CheckConditionVariable(ConditionVar, WhileLoc, true);
+    CondResult = ActOnFinishFullExpr(CondResult.get(), WhileLoc);
     if (CondResult.isInvalid())
       return StmtError();
   }
@@ -1634,6 +1634,7 @@ Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
   if (secondVar) {
     ConditionVar = cast<VarDecl>(secondVar);
     SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
+    SecondResult = ActOnFinishFullExpr(SecondResult.get(), ForLoc);
     if (SecondResult.isInvalid())
       return StmtError();
   }
diff --git a/clang/test/CXX/drs/dr9xx.cpp b/clang/test/CXX/drs/dr9xx.cpp
index 4bcd6565e06..b37e17d6b09 100644
--- a/clang/test/CXX/drs/dr9xx.cpp
+++ b/clang/test/CXX/drs/dr9xx.cpp
@@ -44,3 +44,32 @@ namespace dr990 { // dr990: 3.5
   D d{};
 #endif
 }
+
+namespace dr948 { // dr948: 3.7
+#if __cplusplus >= 201103L
+  class A {
+  public:
+     constexpr A(int v) : v(v) { }
+     constexpr operator int() const { return v; }
+  private:
+     int v;
+  };
+
+  constexpr int id(int x)
+  {
+    return x;
+  }
+
+  void f() {
+     if (constexpr int i = id(101)) { }
+     switch (constexpr int i = id(2)) { default: break; case 2: break; }
+     for (; constexpr int i = id(0); ) { }
+     while (constexpr int i = id(0)) { }
+
+     if (constexpr A i = 101) { }
+     switch (constexpr A i = 2) { default: break; case 2: break; }
+     for (; constexpr A i = 0; ) { }
+     while (constexpr A i = 0) { }
+  }
+#endif
+}