r240707 - [Parse] Allow 'constexpr' in condition declarations

[Meador Inge]

Author: meadori
Date: Thu Jun 25 17:06:40 2015
New Revision: 240707

URL: http://llvm.org/viewvc/llvm-project?rev=240707&view=rev
Log:
[Parse] Allow 'constexpr' in condition declarations

This patch implements the functionality specified by DR948.
The changes are two fold.  First, the parser was modified
to allow 'constexpr's to appear in condition declarations
(which was a hard error before).  Second, Sema was modified
to cleanup maybe odr-used declarations by way of a call to
'ActOnFinishFullExpr'.  As 'constexpr's were not allowed in
condition declarations before the cleanup wasn't necessary
(such declarations were always odr-used).

This fixes PR22491.

Differential Revision: http://reviews.llvm.org/D8978

Modified:
    cfe/trunk/include/clang/Parse/Parser.h
    cfe/trunk/lib/Parse/ParseDecl.cpp
    cfe/trunk/lib/Parse/ParseExprCXX.cpp
    cfe/trunk/lib/Sema/SemaStmt.cpp
    cfe/trunk/test/CXX/drs/dr9xx.cpp

Modified: cfe/trunk/include/clang/Parse/Parser.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Parse/Parser.h?rev=240707&r1=240706&r2=240707&view=diff
==============================================================================
--- cfe/trunk/include/clang/Parse/Parser.h (original)
+++ cfe/trunk/include/clang/Parse/Parser.h Thu Jun 25 17:06:40 2015
@@ -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:

Modified: cfe/trunk/lib/Parse/ParseDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseDecl.cpp?rev=240707&r1=240706&r2=240707&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseDecl.cpp (original)
+++ cfe/trunk/lib/Parse/ParseDecl.cpp Thu Jun 25 17:06:40 2015
@@ -2173,7 +2173,7 @@ void Parser::ParseSpecifierQualifierList
   }
 
   // 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();
   }

Modified: cfe/trunk/lib/Parse/ParseExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseExprCXX.cpp?rev=240707&r1=240706&r2=240707&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseExprCXX.cpp (original)
+++ cfe/trunk/lib/Parse/ParseExprCXX.cpp Thu Jun 25 17:06:40 2015
@@ -1686,7 +1686,7 @@ bool Parser::ParseCXXCondition(ExprResul
   // type-specifier-seq
   DeclSpec DS(AttrFactory);
   DS.takeAttributesFrom(attrs);
-  ParseSpecifierQualifierList(DS);
+  ParseSpecifierQualifierList(DS, AS_none, DSC_condition);
 
   // declarator
   Declarator DeclaratorInfo(DS, Declarator::ConditionContext);

Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=240707&r1=240706&r2=240707&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
+++ cfe/trunk/lib/Sema/SemaStmt.cpp Thu Jun 25 17:06:40 2015
@@ -495,6 +495,7 @@ Sema::ActOnIfStmt(SourceLocation IfLoc,
   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(SourceLocat
   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 Whil
   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
   if (secondVar) {
     ConditionVar = cast<VarDecl>(secondVar);
     SecondResult = CheckConditionVariable(ConditionVar, ForLoc, true);
+    SecondResult = ActOnFinishFullExpr(SecondResult.get(), ForLoc);
     if (SecondResult.isInvalid())
       return StmtError();
   }

Modified: cfe/trunk/test/CXX/drs/dr9xx.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr9xx.cpp?rev=240707&r1=240706&r2=240707&view=diff
==============================================================================
--- cfe/trunk/test/CXX/drs/dr9xx.cpp (original)
+++ cfe/trunk/test/CXX/drs/dr9xx.cpp Thu Jun 25 17:06:40 2015
@@ -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
+}