[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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@240707 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 7b9f8afafb157ca33e2d5984526cb223a3a95e6f..adae6272237939f456af704916bb51238ffc37e1 100644 (file)
--- a/include/clang/Parse/Parser.h
+++ b/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/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index e3294eca46f68e0759b473769df1b335244b8859..f497c59cec1a5964cec1a9d2c0098be490137260 100644 (file)
--- a/lib/Parse/ParseDecl.cpp
+++ b/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/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index 7fb4b5e5a07f35e5800b21c1f533b12a355e7d2e..02176c410592fff5192bbaea884b3fe5290425e7 100644 (file)
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/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/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 50e4345216a6ceb2a1fa8f83c771232460094ef9..6fca974d5b36657784f27eb18e199048dedfff25 100644 (file)
--- a/lib/Sema/SemaStmt.cpp
+++ b/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/test/CXX/drs/dr9xx.cpp b/test/CXX/drs/dr9xx.cpp
index 4bcd6565e06869d0a3cda8eb8a0a1ab1507472b4..b37e17d6b098ded4167918529b02c5d822485011 100644 (file)
--- a/test/CXX/drs/dr9xx.cpp
+++ b/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
+}