C99 DR #316 implies that the function parameter types that are known

only from a function definition (that does not have a prototype) are
only used to determine the compatible with other declarations of that
same function. In particular, when referencing the function we pretend
as if it does not have a prototype. Implement this behavior, which
fixes PR3626.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65460 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 21 insertions, 2 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index abb5e40dd4..c312195972 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -334,7 +334,8 @@ NamedDecl *Sema::LazilyCreateBuiltin(IdentifierInfo *II, unsigned bid,
   FunctionDecl *New = FunctionDecl::Create(Context,
                                            Context.getTranslationUnitDecl(),
                                            Loc, II, R,
-                                           FunctionDecl::Extern, false);
+                                           FunctionDecl::Extern, false,
+                                           /*hasPrototype=*/true);
   New->setImplicit();
 
   // Create Decl objects for each parameter, adding them to the
@@ -1736,6 +1737,7 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
       // code path.
       NewFD = FunctionDecl::Create(Context, DC, D.getIdentifierLoc(),
                                    Name, R, SC, isInline, 
+                                   /*hasPrototype=*/true,
                                    // FIXME: Move to DeclGroup...
                                    D.getDeclSpec().getSourceRange().getBegin());
       InvalidDecl = true;
@@ -1765,6 +1767,10 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
     NewFD = FunctionDecl::Create(Context, DC,
                                  D.getIdentifierLoc(),
                                  Name, R, SC, isInline, 
+                                 /*hasPrototype=*/
+                                   (getLangOptions().CPlusPlus ||
+                                    (D.getNumTypeObjects() &&
+                                     D.getTypeObject(0).Fun.hasPrototype)),
                                  // FIXME: Move to DeclGroup...
                                  D.getDeclSpec().getSourceRange().getBegin());
   }
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 174e408ead..98d6b12b9c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -873,6 +873,19 @@ Sema::ActOnDeclarationNameExpr(Scope *S, SourceLocation Loc,
           CheckS = CheckS->getParent();
       }
     }
+  } else if (FunctionDecl *Func = dyn_cast<FunctionDecl>(VD)) {
+    if (!getLangOptions().CPlusPlus && !Func->hasPrototype()) {
+      // C99 DR 316 says that, if a function type comes from a
+      // function definition (without a prototype), that type is only
+      // used for checking compatibility. Therefore, when referencing
+      // the function, we pretend that we don't have the full function
+      // type.
+      QualType T = Func->getType();
+      QualType NoProtoType = T;
+      if (const FunctionTypeProto *Proto = T->getAsFunctionTypeProto())
+        NoProtoType = Context.getFunctionTypeNoProto(Proto->getResultType());
+      return Owned(BuildDeclRefExpr(VD, NoProtoType, Loc, false, false, SS));
+    }
   }
 
   // Only create DeclRefExpr's for valid Decl's.
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index ea59b644c9..c8671bc2e3 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -543,7 +543,7 @@ void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
   QualType FnType = Context.getFunctionType(Return, &Argument, 1, false, 0);
   FunctionDecl *Alloc =
     FunctionDecl::Create(Context, GlobalCtx, SourceLocation(), Name,
-                         FnType, FunctionDecl::None, false,
+                         FnType, FunctionDecl::None, false, true,
                          SourceLocation());
   Alloc->setImplicit();
   ParmVarDecl *Param = ParmVarDecl::Create(Context, Alloc, SourceLocation(),