small test and documentation fixes

Author: balazske

clang/docs/analyzer/checkers.rst

@@ -1914,7 +1914,7 @@ is missing.
 .. code-block:: c
 
  void test1() {
-   int l = strlen((char *)&test); // warn
+   int l = strlen((char *)&test1); // warn
  }
 
  void test2() {

clang/test/Analysis/string.cpp

@@ -55,5 +55,8 @@ struct TestNotNullTerm {
 };
 
 void test_notcstring_tempobject() {
+  // FIXME: This warning from cstring.NotNullTerminated is a false positive.
+  // Handling of similar cases is not perfect in other cstring checkers.
+  // The fix would be a larger change in CStringChecker and affect multiple checkers.
   strlen((char[]){'a', 0}); // expected-warning{{Argument to string length function is a C++ temp object of type char[2], which is not a null-terminated string}}
 }

clang/test/Analysis/string_notnullterm.c

@@ -0,0 +1,10 @@
+// RUN: %clang_analyze_cc1 -verify %s -Wno-null-dereference \
+// RUN:   -analyzer-checker=core \
+// RUN:   -analyzer-checker=unix.cstring.NotNullTerminated \
+// RUN:   -analyzer-checker=debug.ExprInspection
+
+char *strcpy(char *restrict s1, const char *restrict s2);
+
+void strcpy_fn(char *x) {
+  strcpy(x, (char*)&strcpy_fn); // expected-warning{{Argument to string copy function is the address of the function 'strcpy_fn', which is not a null-terminated string}}
+}