[analyzer] suppress nullability inference from a macro when result is used in another macro

The current code used to not suppress the report, if the dereference was
performed in a macro, assuming it is that same macro.
However, the assumption might not be correct, and XNU has quite a bit of
code where dereference is actually performed in a different macro.

As the code uses macro name and not a unique identifier it might be fragile,
but in a worst-case scenario we would simply emit an extra diagnostic.

rdar://36160245

Differential Revision: https://reviews.llvm.org/D41749

llvm-svn: 322149

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/test/Analysis/inlining/false-positive-suppression.c b/clang/test/Analysis/inlining/false-positive-suppression.c
index 4931695ef12..5f613e12c2f 100644
--- a/clang/test/Analysis/inlining/false-positive-suppression.c
+++ b/clang/test/Analysis/inlining/false-positive-suppression.c
@@ -163,6 +163,7 @@ void testNestedDisjunctiveMacro2(int *p, int *q) {
 }
 
 
+
 // Here the check is entirely in non-macro code even though the code itself
 // is a macro argument.
 #define MACRO_DO_IT(a) (a)
@@ -171,6 +172,15 @@ void testErrorInArgument(int *p) {
   (void)i;
 }
 
+// No warning should be emitted if dereference is performed from a different
+// macro.
+#define MACRO_CHECK(a) if (a) {}
+#define MACRO_DEREF(a) (*a)
+int testDifferentMacro(int *p) {
+  MACRO_CHECK(p);
+  return MACRO_DEREF(p); // no-warning
+}
+
 // --------------------------
 // "Suppression suppression"
 // --------------------------