[clang] 9a72580 - [clang][Sema] removes -Wfree-nonheap-object reference param false positive

[Christopher Di Bella via cfe-commits]

Author: Christopher Di Bella
Date: 2021-07-21T21:30:16Z
New Revision: 9a72580a548da8008dca479ec50e4eb75e56db71

URL: https://github.com/llvm/llvm-project/commit/9a72580a548da8008dca479ec50e4eb75e56db71
DIFF: https://github.com/llvm/llvm-project/commit/9a72580a548da8008dca479ec50e4eb75e56db71.diff

LOG: [clang][Sema] removes -Wfree-nonheap-object reference param false positive

Taking the address of a reference parameter might be valid, and without
CFA, false positives are going to be more trouble than they're worth.

Differential Revision: https://reviews.llvm.org/D102728

Added: 
    

Modified: 
    clang/lib/Sema/SemaChecking.cpp
    clang/test/Sema/warn-free-nonheap-object.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 075fad6476ef..242c2968da45 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -10726,8 +10726,9 @@ void CheckFreeArgumentsAddressof(Sema &S, const std::string &CalleeName,
                                  const UnaryOperator *UnaryExpr) {
   if (const auto *Lvalue = dyn_cast<DeclRefExpr>(UnaryExpr->getSubExpr())) {
     const Decl *D = Lvalue->getDecl();
-    if (isa<VarDecl, FunctionDecl>(D))
-      return CheckFreeArgumentsOnLvalue(S, CalleeName, UnaryExpr, D);
+    if (isa<DeclaratorDecl>(D))
+      if (!dyn_cast<DeclaratorDecl>(D)->getType()->isReferenceType())
+        return CheckFreeArgumentsOnLvalue(S, CalleeName, UnaryExpr, D);
   }
 
   if (const auto *Lvalue = dyn_cast<MemberExpr>(UnaryExpr->getSubExpr()))

diff  --git a/clang/test/Sema/warn-free-nonheap-object.cpp b/clang/test/Sema/warn-free-nonheap-object.cpp
index 9347709a23ca..37dc0fdaad93 100644
--- a/clang/test/Sema/warn-free-nonheap-object.cpp
+++ b/clang/test/Sema/warn-free-nonheap-object.cpp
@@ -10,23 +10,34 @@ void free(void *p);
 
 int GI;
 
+void free_reference(char &x) { ::free(&x); }
+void free_reference(char &&x) { ::free(&x); }
+void std_free_reference(char &x) { std::free(&x); }
+void std_free_reference(char &&x) { std::free(&x); }
+
 struct S {
-  operator char *() { return ptr; }
+  operator char *() { return ptr1; }
 
   void CFree() {
-    ::free(&ptr); // expected-warning {{attempt to call free on non-heap object 'ptr'}}
-    ::free(&I);   // expected-warning {{attempt to call free on non-heap object 'I'}}
-    ::free(ptr);
+    ::free(&ptr1); // expected-warning {{attempt to call free on non-heap object 'ptr1'}}
+    ::free(&I);    // expected-warning {{attempt to call free on non-heap object 'I'}}
+    ::free(ptr1);
+    free_reference(*ptr2);
+    free_reference(static_cast<char&&>(*ptr3));
   }
 
   void CXXFree() {
-    std::free(&ptr); // expected-warning {{attempt to call std::free on non-heap object 'ptr'}}
-    std::free(&I);   // expected-warning {{attempt to call std::free on non-heap object 'I'}}
-    std::free(ptr);
+    std::free(&ptr1); // expected-warning {{attempt to call std::free on non-heap object 'ptr1'}}
+    std::free(&I);    // expected-warning {{attempt to call std::free on non-heap object 'I'}}
+    std::free(ptr1);
+    std_free_reference(*ptr2);
+    std_free_reference(static_cast<char&&>(*ptr3));
   }
 
 private:
-  char *ptr = (char *)std::malloc(10);
+  char *ptr1 = (char *)std::malloc(10);
+  char *ptr2 = (char *)std::malloc(10);
+  char *ptr3 = (char *)std::malloc(10);
   static int I;
 };
 
@@ -93,6 +104,14 @@ void test2() {
     void *P = std::malloc(8);
     std::free(P);
   }
+  {
+    char* P = (char *)std::malloc(2);
+    std_free_reference(*P);
+  }
+  {
+    char* P = (char *)std::malloc(2);
+    std_free_reference(static_cast<char&&>(*P));
+  }
   {
     int A[] = {0, 1, 2, 3};
     std::free(A); // expected-warning {{attempt to call std::free on non-heap object 'A'}}