Reapply "[analyzer] Accept C library functions from the std namespace" again

clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp

@@ -394,8 +394,10 @@ class MallocChecker
                                      const CallEvent &Call, CheckerContext &C)>;
 
   const CallDescriptionMap<CheckFn> PreFnMap{
-      {{{"getline"}, 3}, &MallocChecker::preGetdelim},
-      {{{"getdelim"}, 4}, &MallocChecker::preGetdelim},
+      // NOTE: the following CallDescription also matches the C++ standard
+      // library function std::getline(); the callback will filter it out.
+      {{CDM::CLibrary, {"getline"}, 3}, &MallocChecker::preGetdelim},
+      {{CDM::CLibrary, {"getdelim"}, 4}, &MallocChecker::preGetdelim},
   };
 
   const CallDescriptionMap<CheckFn> FreeingMemFnMap{
@@ -446,8 +448,11 @@ class MallocChecker
        std::bind(&MallocChecker::checkRealloc, _1, _2, _3, false)},
       {{{"g_realloc_n"}, 3}, &MallocChecker::checkReallocN},
       {{{"g_try_realloc_n"}, 3}, &MallocChecker::checkReallocN},
-      {{{"getline"}, 3}, &MallocChecker::checkGetdelim},
-      {{{"getdelim"}, 4}, &MallocChecker::checkGetdelim},
+
+      // NOTE: the following CallDescription also matches the C++ standard
+      // library function std::getline(); the callback will filter it out.
+      {{CDM::CLibrary, {"getline"}, 3}, &MallocChecker::checkGetdelim},
+      {{CDM::CLibrary, {"getdelim"}, 4}, &MallocChecker::checkGetdelim},
   };
 
   bool isMemCall(const CallEvent &Call) const;
@@ -1435,9 +1440,17 @@ void MallocChecker::checkGMallocN0(const CallEvent &Call,
   C.addTransition(State);
 }
 
+static bool isFromStdNamespace(const CallEvent &Call) {
+  const Decl *FD = Call.getDecl();
+  assert(FD && "a CallDescription cannot match a call without a Decl");
+  return (FD->isInStdNamespace());
+}
+
 void MallocChecker::preGetdelim(const CallEvent &Call,
                                 CheckerContext &C) const {
-  if (!Call.isGlobalCFunction())
+  // Discard calls to the C++ standard library function std::getline(), which
+  // is completely unrelated to the POSIX getline() that we're checking.
+  if (isFromStdNamespace(Call))
     return;
 
   ProgramStateRef State = C.getState();
@@ -1458,7 +1471,9 @@ void MallocChecker::preGetdelim(const CallEvent &Call,
 
 void MallocChecker::checkGetdelim(const CallEvent &Call,
                                   CheckerContext &C) const {
-  if (!Call.isGlobalCFunction())
+  // Discard calls to the C++ standard library function std::getline(), which
+  // is completely unrelated to the POSIX getline() that we're checking.
+  if (isFromStdNamespace(Call))
     return;
 
   ProgramStateRef State = C.getState();

clang/test/Analysis/Inputs/system-header-simulator-cxx.h

@@ -1106,11 +1106,20 @@ using ostream = basic_ostream<char>;
 extern std::ostream cout;
 
 ostream &operator<<(ostream &, const string &);
-
 #if __cplusplus >= 202002L
 template <class T>
 ostream &operator<<(ostream &, const std::unique_ptr<T> &);
 #endif
+
+template <class CharT>
+class basic_istream;
+
+using istream = basic_istream<char>;
+
+extern std::istream cin;
+
+istream &getline(istream &, string &, char);
+istream &getline(istream &, string &);
 } // namespace std
 
 #ifdef TEST_INLINABLE_ALLOCATORS

clang/test/Analysis/getline-cpp.cpp

@@ -0,0 +1,15 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,unix,debug.ExprInspection -verify %s
+
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,unix,alpha.unix,debug.ExprInspection -verify %s
+//
+// expected-no-diagnostics
+
+#include "Inputs/system-header-simulator-cxx.h"
+
+void test_std_getline() {
+  std::string userid, comment;
+  // MallocChecker should not confuse the POSIX function getline() and the
+  // unrelated C++ standard library function std::getline.
+  std::getline(std::cin, userid, ' '); // no-crash
+  std::getline(std::cin, comment); // no-crash
+}