From dce6c58db87ebf7f4477bd3126228e73e4eeee97 Mon Sep 17 00:00:00 2001
From: Martin Sebor <msebor@redhat.com>
Date: Thu, 3 Dec 2020 15:41:25 -0700
Subject: Add support for detecting mismatched allocation/deallocation calls.

PR c++/90629 - Support for -Wmismatched-new-delete
PR middle-end/94527 - Add an __attribute__ that marks a function as freeing an object

gcc/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* builtins.c (access_ref::access_ref): Initialize new member.
	(compute_objsize): Use access_ref::deref.  Handle simple pointer
	assignment.
	(expand_builtin): Remove handling of the free built-in.
	(call_dealloc_argno): Same.
	(find_assignment_location): New function.
	(fndecl_alloc_p): Same.
	(gimple_call_alloc_p): Same.
	(call_dealloc_p): Same.
	(matching_alloc_calls_p): Same.
	(warn_dealloc_offset): Same.
	(maybe_emit_free_warning): Same.
	* builtins.h (struct access_ref): Declare new member.
	(maybe_emit_free_warning): Make extern.  Make use of access_ref.
	Handle -Wmismatched-new-delete.
	* calls.c (initialize_argument_information): Call
	maybe_emit_free_warning.
	* doc/extend.texi (attribute malloc): Update.
	* doc/invoke.texi (-Wfree-nonheap-object): Expand documentation.
	(-Wmismatched-new-delete): Document new option.
	(-Wmismatched-dealloc): Document new option.

gcc/c-family/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* c-attribs.c (handle_dealloc_attribute): New function.
	(handle_malloc_attribute): Handle argument forms of attribute.
	* c.opt (-Wmismatched-dealloc): New option.
	(-Wmismatched-new-delete): New option.

gcc/testsuite/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* g++.dg/asan/asan_test.cc: Fix a bug.
	* g++.dg/warn/delete-array-1.C: Add expected warning.
	* g++.old-deja/g++.other/delete2.C: Add expected warning.
	* g++.dg/warn/Wfree-nonheap-object-2.C: New test.
	* g++.dg/warn/Wfree-nonheap-object.C: New test.
	* g++.dg/warn/Wmismatched-new-delete.C: New test.
	* g++.dg/warn/Wmismatched-dealloc-2.C: New test.
	* g++.dg/warn/Wmismatched-dealloc.C: New test.
	* gcc.dg/Wmismatched-dealloc.c: New test.
	* gcc.dg/analyzer/malloc-1.c: Prune out expected warning.
	* gcc.dg/attr-malloc.c: New test.
	* gcc.dg/free-1.c: Adjust text of expected warning.
	* gcc.dg/free-2.c: Same.
	* gcc.dg/torture/pr71816.c: Prune out expected warning.
	* gcc.dg/tree-ssa/pr19831-2.c: Add an expected warning.
	* gcc.dg/Wfree-nonheap-object-2.c: New test.
	* gcc.dg/Wfree-nonheap-object-3.c: New test.
	* gcc.dg/Wfree-nonheap-object.c: New test.

libstdc++-v3/ChangeLog:

	* testsuite/ext/vstring/modifiers/clear/56166.cc: Suppress a false
	positive warning.
---
 gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c | 57 +++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c

(limited to 'gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c')

diff --git a/gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c b/gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c
new file mode 100644
index 0000000..a472b93
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wfree-nonheap-object-3.c
@@ -0,0 +1,57 @@
+/* PR ????? - No warning on attempts to access free object
+   Verify that freeing unallocated objects referenced indirectly through
+   pointers obtained from function calls is diagnosed.
+   { dg-do compile }
+   { dg-options "-O2 -Wall -Wfree-nonheap-object" }  */
+
+typedef __SIZE_TYPE__ size_t;
+
+extern void free (void*);
+extern char* memchr (const void*, int, size_t);
+extern char* strchr (const char*, int);
+
+void sink (void*, ...);
+
+extern char ecarr[];
+extern void* eparr[];
+
+extern char *eptr;
+
+
+void warn_free_memchr_ecarr (int x, size_t n)
+{
+  char *p = memchr (ecarr, x, n);
+  sink (p);
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_memchr_ecarr_offset (int i, int j, int x, size_t n)
+{
+  char *p = memchr (ecarr + i, x, n);
+  char *q = p + j;
+  sink (p, q);
+  free (q);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+void warn_free_memchr_local_arr (int x, size_t n)
+{
+  char a[8];
+  sink (a);
+
+  char *p = memchr (a, x, n);
+  sink (p);
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_memchr_local_arr_offset (int i, int j, int x, size_t n)
+{
+  char a[8];
+  sink (a);
+
+  char *p = memchr (a + i, x, n);
+  char *q = p + j;
+  sink (p, q);
+  free (q);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
-- 
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