[clang] [clang] Move warning about memset/memcpy to NonTriviallyCopyable type… (PR #117387)

[via cfe-commits]

https://github.com/serge-sans-paille updated https://github.com/llvm/llvm-project/pull/117387

>From fda70bc5aeabe33fc578fbb2f55bc805a3304059 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton at mozilla.com>
Date: Fri, 22 Nov 2024 22:38:23 +0100
Subject: [PATCH 1/2] [clang] Move warning about memset/memcpy to
 NonTriviallyCopyable types to its own flag

Namely -Wnontrivial-memcall, implied by -Wnontricial-memaccess

This is a followup to #111434
---
 clang/docs/ReleaseNotes.rst                   |  2 +-
 clang/include/clang/Basic/DiagnosticGroups.td |  6 +++--
 .../clang/Basic/DiagnosticSemaKinds.td        |  2 +-
 clang/test/SemaCXX/warn-memcall.cpp           | 27 +++++++++++++++++++
 4 files changed, 33 insertions(+), 4 deletions(-)
 create mode 100644 clang/test/SemaCXX/warn-memcall.cpp

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8bd06fadfdc984..80b521001bbd2f 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -404,7 +404,7 @@ Modified Compiler Flags
   to utilize these vector libraries. The behavior for all other vector function
   libraries remains unchanged.
 
-- The ``-Wnontrivial-memaccess`` warning has been updated to also warn about
+- The ``-Wnontrivial-memcall`` warning has been updated to also warn about
   passing non-trivially-copyable destrination parameter to ``memcpy``,
   ``memset`` and similar functions for which it is a documented undefined
   behavior.
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index df9bf94b5d0398..e20c3f8bbb26a5 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -683,11 +683,13 @@ def SizeofArrayDecay : DiagGroup<"sizeof-array-decay">;
 def SizeofPointerMemaccess : DiagGroup<"sizeof-pointer-memaccess">;
 def MemsetTransposedArgs : DiagGroup<"memset-transposed-args">;
 def DynamicClassMemaccess : DiagGroup<"dynamic-class-memaccess">;
-def NonTrivialMemaccess : DiagGroup<"nontrivial-memaccess">;
+def NonTrivialMemcall : DiagGroup<"nontrivial-memcall">;
+def NonTrivialMemaccess : DiagGroup<"nontrivial-memaccess", [NonTrivialMemcall]>;
 def SuspiciousBzero : DiagGroup<"suspicious-bzero">;
 def SuspiciousMemaccess : DiagGroup<"suspicious-memaccess",
   [SizeofPointerMemaccess, DynamicClassMemaccess,
-   NonTrivialMemaccess, MemsetTransposedArgs, SuspiciousBzero]>;
+   NonTrivialMemaccess, NonTrivialMemcall, MemsetTransposedArgs,
+   SuspiciousBzero]>;
 def StaticInInline : DiagGroup<"static-in-inline">;
 def StaticLocalInInline : DiagGroup<"static-local-in-inline">;
 def GNUStaticFloatInit : DiagGroup<"gnu-static-float-init">;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index eb05a6a77978af..cc35c2c58baad0 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -798,7 +798,7 @@ def warn_cstruct_memaccess : Warning<
 def warn_cxxstruct_memaccess : Warning<
   "first argument in call to "
   "%0 is a pointer to non-trivially copyable type %1">,
-  InGroup<NonTrivialMemaccess>;
+  InGroup<NonTrivialMemcall>;
 def note_nontrivial_field : Note<
   "field is non-trivial to %select{copy|default-initialize}0">;
 def err_non_trivial_c_union_in_invalid_context : Error<
diff --git a/clang/test/SemaCXX/warn-memcall.cpp b/clang/test/SemaCXX/warn-memcall.cpp
new file mode 100644
index 00000000000000..fbc9f25a5f65bc
--- /dev/null
+++ b/clang/test/SemaCXX/warn-memcall.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wnontrivial-memcall %s
+
+extern "C" void *memcpy(void *s1, const void *s2, unsigned n);
+
+class TriviallyCopyable {};
+class NonTriviallyCopyable { NonTriviallyCopyable(const NonTriviallyCopyable&);};
+struct Incomplete;
+
+void test_memcpy(TriviallyCopyable* tc0, TriviallyCopyable* tc1,
+                 NonTriviallyCopyable *ntc0, NonTriviallyCopyable *ntc1,
+                 Incomplete *i0, Incomplete *i1) {
+  // OK
+  memcpy(tc0, tc1, sizeof(*tc0));
+
+  // OK
+  memcpy(i0, i1, 10);
+
+  // expected-warning at +2{{first argument in call to 'memcpy' is a pointer to non-trivially copyable type 'NonTriviallyCopyable'}}
+  // expected-note at +1{{explicitly cast the pointer to silence this warning}}
+  memcpy(ntc0, ntc1, sizeof(*ntc0));
+
+  // ~ OK
+  memcpy((void*)ntc0, ntc1, sizeof(*ntc0));
+
+  // OK
+  memcpy((void*)ntc0, (void*)ntc1, sizeof(*ntc0));
+}

>From a9b2bbbb0af616710782beedacdc3ac61d68dfa7 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton at mozilla.com>
Date: Wed, 27 Nov 2024 15:48:05 +0100
Subject: [PATCH 2/2] fixup! [clang] Move warning about memset/memcpy to
 NonTriviallyCopyable types to its own flag

---
 clang/docs/ReleaseNotes.rst                   | 4 ++--
 clang/include/clang/Basic/DiagnosticGroups.td | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 80b521001bbd2f..cee72f897a9778 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -404,10 +404,10 @@ Modified Compiler Flags
   to utilize these vector libraries. The behavior for all other vector function
   libraries remains unchanged.
 
-- The ``-Wnontrivial-memcall`` warning has been updated to also warn about
+- The ``-Wnontrivial-memcall`` warning has been added to warn about
   passing non-trivially-copyable destrination parameter to ``memcpy``,
   ``memset`` and similar functions for which it is a documented undefined
-  behavior.
+  behavior. It is implied by ``-Wnontrivial-memaccess``
 
 Removed Compiler Flags
 -------------------------
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index e20c3f8bbb26a5..bb37e142b3bcb7 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -688,8 +688,7 @@ def NonTrivialMemaccess : DiagGroup<"nontrivial-memaccess", [NonTrivialMemcall]>
 def SuspiciousBzero : DiagGroup<"suspicious-bzero">;
 def SuspiciousMemaccess : DiagGroup<"suspicious-memaccess",
   [SizeofPointerMemaccess, DynamicClassMemaccess,
-   NonTrivialMemaccess, NonTrivialMemcall, MemsetTransposedArgs,
-   SuspiciousBzero]>;
+   NonTrivialMemaccess, MemsetTransposedArgs, SuspiciousBzero]>;
 def StaticInInline : DiagGroup<"static-in-inline">;
 def StaticLocalInInline : DiagGroup<"static-local-in-inline">;
 def GNUStaticFloatInit : DiagGroup<"gnu-static-float-init">;