Clean up the sentinel-attribute checking code a lot. Document

what 'nullPos' is supposed to mean, at least at this one site.
Use closed forms for the arithmetic.  Rip out some clever but
ultimately pointless code that was trying to use 0 or 0L depending
the size of a pointer vs. the size of int;  first, it didn't work
on LLP64 systems, and second, the sentinel checking code requires
a pointer-typed value anyway, so this fixit would not have actually
removed the warning.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@139361 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 8 deletions

diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index a77454e814..624ac086db 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -1771,7 +1771,7 @@ static void handleSentinelAttr(Sema &S, Decl *D, const AttributeList &Attr) {
     return;
   }
 
-  int sentinel = 0;
+  unsigned sentinel = 0;
   if (Attr.getNumArgs() > 0) {
     Expr *E = Attr.getArg(0);
     llvm::APSInt Idx(32);
@@ -1781,16 +1781,17 @@ static void handleSentinelAttr(Sema &S, Decl *D, const AttributeList &Attr) {
        << "sentinel" << 1 << E->getSourceRange();
       return;
     }
-    sentinel = Idx.getZExtValue();
 
-    if (sentinel < 0) {
+    if (Idx.isSigned() && Idx.isNegative()) {
       S.Diag(Attr.getLoc(), diag::err_attribute_sentinel_less_than_zero)
         << E->getSourceRange();
       return;
     }
+
+    sentinel = Idx.getZExtValue();
   }
 
-  int nullPos = 0;
+  unsigned nullPos = 0;
   if (Attr.getNumArgs() > 1) {
     Expr *E = Attr.getArg(1);
     llvm::APSInt Idx(32);
@@ -1802,7 +1803,7 @@ static void handleSentinelAttr(Sema &S, Decl *D, const AttributeList &Attr) {
     }
     nullPos = Idx.getZExtValue();
 
-    if (nullPos > 1 || nullPos < 0) {
+    if ((Idx.isSigned() && Idx.isNegative()) || nullPos > 1) {
       // FIXME: This error message could be improved, it would be nice
       // to say what the bounds actually are.
       S.Diag(Attr.getLoc(), diag::err_attribute_sentinel_not_zero_or_one)
@@ -1812,9 +1813,7 @@ static void handleSentinelAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   }
 
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
-    const FunctionType *FT = FD->getType()->getAs<FunctionType>();
-    assert(FT && "FunctionDecl has non-function type?");
-
+    const FunctionType *FT = FD->getType()->castAs<FunctionType>();
     if (isa<FunctionNoProtoType>(FT)) {
       S.Diag(Attr.getLoc(), diag::warn_attribute_sentinel_named_arguments);
       return;