Extend tautological pointer compare and pointer to bool conversion warnings to

macro arguments.

Previously, these warnings skipped any code in a macro expansion.  Preform an
additional check and warn when the expression and context locations are both
in the macro argument.

The most obvious case not caught is passing a pointer directly to a macro,
i.e 'assert(&array)' but 'assert(&array && "valid array")' is caught.  This is
because macro arguments are not typed and the conversion happens inside the
macro.

llvm-svn: 215251

1 files changed, 21 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 0483341cef1..7bc3ba7febc 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6340,6 +6340,22 @@ static bool CheckForReference(Sema &SemaRef, const Expr *E,
   return true;
 }
 
+// Returns true if the SourceLocation is expanded from any macro body.
+// Returns false if the SourceLocation is invalid, is from not in a macro
+// expansion, or is from expanded from a top-level macro argument.
+static bool IsInAnyMacroBody(const SourceManager &SM, SourceLocation Loc) {
+  if (Loc.isInvalid())
+    return false;
+
+  while (Loc.isMacroID()) {
+    if (SM.isMacroBodyExpansion(Loc))
+      return true;
+    Loc = SM.getImmediateMacroCallerLoc(Loc);
+  }
+
+  return false;
+}
+
 /// \brief Diagnose pointers that are always non-null.
 /// \param E the expression containing the pointer
 /// \param NullKind NPCK_NotNull if E is a cast to bool, otherwise, E is
@@ -6353,8 +6369,12 @@ void Sema::DiagnoseAlwaysNonNullPointer(Expr *E,
     return;
 
   // Don't warn inside macros.
-  if (E->getExprLoc().isMacroID())
+  if (E->getExprLoc().isMacroID()) {
+    const SourceManager &SM = getSourceManager();
+    if (IsInAnyMacroBody(SM, E->getExprLoc()) ||
+        IsInAnyMacroBody(SM, Range.getBegin()))
       return;
+  }
   E = E->IgnoreImpCasts();
 
   const bool IsCompare = NullKind != Expr::NPCK_NotNull;