[binutils-gdb] gdb, testsuite, fortran: fix double free in mixed-lang-stack.exp

[binutils-gdb] gdb, testsuite, fortran: fix double free in mixed-lang-stack.exp

[Nils-Christian Kempke]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a60ead5ded5f9fc548018637d4810cb5f313ad8c

commit a60ead5ded5f9fc548018637d4810cb5f313ad8c
Author: Nils-Christian Kempke <nils-christian.kempke@intel.com>
Date:   Tue May 31 16:43:45 2022 +0200

    gdb, testsuite, fortran: fix double free in mixed-lang-stack.exp
    
    While testing mixed-lang-stack I realized that valgrind actually
    complained about a double free in the test.
    
       All done
      ==2503051==
      ==2503051== HEAP SUMMARY:
      ==2503051==     in use at exit: 0 bytes in 0 blocks
      ==2503051==   total heap usage: 26 allocs, 27 frees, 87,343 bytes allocated
      ==2503051==
      ==2503051== All heap blocks were freed -- no leaks are possible
      ==2503051==
      ==2503051== For lists of detected and suppressed errors, rerun with: -s
      ==2503051== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
    
    Reason for this is that in mixed-lang-stack.cpp in mixed_func_1f an
    object "derived_type obj" goes on the stack which is then passed-by-value
    (so copied) to mixed_func_1g.  The default copy-ctor will be called but,
    since derived_type contains a heap allocated string and the copy
    constructor is not implemented it will only be able to shallow copy the
    object.  Right after each of the functions the object gets freed - on the
    other hand the d'tor of derived_type actually is implemented and calls
    free on the heap allocated string which leads to a double free.  Instead
    of obeying the rule of 3/5 I just got rid of all that since it does not
    serve the test.  The string is now just a const char* = ".." object
    member.

Diff:
---
 gdb/testsuite/gdb.fortran/mixed-lang-stack.cpp | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/gdb/testsuite/gdb.fortran/mixed-lang-stack.cpp b/gdb/testsuite/gdb.fortran/mixed-lang-stack.cpp
index 39ff6c201f7..b5ae7dac0a8 100644
--- a/gdb/testsuite/gdb.fortran/mixed-lang-stack.cpp
+++ b/gdb/testsuite/gdb.fortran/mixed-lang-stack.cpp
@@ -26,17 +26,7 @@ class base_one
 class base_two
 {
 public:
-  base_two ()
-  {
-    string = strdup ("Something in C++");
-  }
-
-  ~base_two ()
-  {
-    free (string);
-  }
-
-  char *string = nullptr;
+  const char *string = "Something in C++";
   float val = 3.5;
 };