[analyzer] Nullability: Suppress return diagnostics in inlined functions.

The nullability checker can sometimes miss detecting nullability precondition
violations in inlined functions because the binding for the parameter
that violated the precondition becomes dead before the return:

int * _Nonnull callee(int * _Nonnull p2) {
  if (!p2)
    // p2 becomes dead here, so binding removed.
    return 0; // warning here because value stored in p2 is symbolic.
  else
   return p2;
}

int *caller(int * _Nonnull p1) {
  return callee(p1);
}

The fix, which is quite blunt, is to not warn about null returns in inlined
methods/functions. This won’t lose much coverage for ObjC because the analyzer
always analyzes each ObjC method at the top level in addition to inlined. It
*will* lose coverage for C — but there aren’t that many codebases with C
nullability annotations.

rdar://problem/25615050

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@266109 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp b/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
index 35620d33acf1974eab4a93a5f59330b91b60431f..d8a224ea2f458aa2aae18256b81bf482000083d6 100644 (file)
--- a/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
@@ -562,7 +562,8 @@ void NullabilityChecker::checkPreStmt(const ReturnStmt *S,
   if (Filter.CheckNullReturnedFromNonnull &&
       NullReturnedFromNonNull &&
       RetExprTypeLevelNullability != Nullability::Nonnull &&
-      !InSuppressedMethodFamily) {
+      !InSuppressedMethodFamily &&
+      C.getLocationContext()->inTopFrame()) {
     static CheckerProgramPointTag Tag(this, "NullReturnedFromNonnull");
     ExplodedNode *N = C.generateErrorNode(State, &Tag);
     if (!N)

diff --git a/test/Analysis/nullability.mm b/test/Analysis/nullability.mm
index 0a3ae7a1968c6fedc83aea25f32b1a042d35fd07..1e01cdf4ca6ba5c3dece6b032d991b5692d08b67 100644 (file)
--- a/test/Analysis/nullability.mm
+++ b/test/Analysis/nullability.mm
@@ -238,6 +238,41 @@ void testPreconditionViolationInInlinedFunction(Dummy *p) {
   doNotWarnWhenPreconditionIsViolated(p);
 }
 
+@interface TestInlinedPreconditionViolationClass : NSObject
+@end
+
+@implementation TestInlinedPreconditionViolationClass
+-(Dummy * _Nonnull) calleeWithParam:(Dummy * _Nonnull) p2 {
+  Dummy *x = 0;
+  if (!p2) // p2 binding becomes dead at this point.
+    return x; // no-warning
+  else
+   return p2;
+}
+
+-(Dummy *)callerWithParam:(Dummy * _Nonnull) p1 {
+  return [self calleeWithParam:p1];
+}
+
+@end
+
+int * _Nonnull InlinedPreconditionViolationInFunctionCallee(int * _Nonnull p2) {
+  int *x = 0;
+  if (!p2) // p2 binding becomes dead at this point.
+    return x; // no-warning
+  else
+   return p2;
+}
+
+int * _Nonnull InlinedReturnNullOverSuppressionCallee(int * _Nonnull p2) {
+  int *result = 0;
+  return result; // no-warning; but this is an over suppression
+}
+
+int *InlinedReturnNullOverSuppressionCaller(int * _Nonnull p1) {
+  return InlinedReturnNullOverSuppressionCallee(p1);
+}
+
 void inlinedNullable(Dummy *_Nullable p) {
   if (p) return;
 }