From f86e6f8eb0fd13025c61b2e1b583628721878103 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Steven=20Dee=20=28J=C5=8Dshin=29?= <git@wholezero.org>
Date: Thu, 20 Jun 2024 12:20:54 -0700
Subject: [PATCH] Make new.cc definitions weak (#1233)
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The STL says that these should be replaceable by user code.

new.cc now defines only a few direct functions (including a free wrapper
that perplexingly is needed since g++ didn’t want to alias "free".) Now,
all of the operators are weak references to those functions.
---
 ctl/new.cc | 131 +++++++++++++++++++++++------------------------------
 ctl/new.h  |  11 +++--
 2 files changed, 64 insertions(+), 78 deletions(-)

diff --git a/ctl/new.cc b/ctl/new.cc
index 7cac144ec..5df2d54ff 100644
--- a/ctl/new.cc
+++ b/ctl/new.cc
@@ -20,97 +20,80 @@
 
 #include "libc/mem/mem.h"
 
-using ctl::align_val_t;
+COSMOPOLITAN_C_START_
 
-namespace {
-
-constexpr auto a1 = align_val_t(1);
-
-} // namespace
-
-void*
-operator new(size_t n, align_val_t a)
+static void*
+_ctl_alloc(size_t n, size_t a)
 {
     void* p;
-    if (!(p = memalign(static_cast<size_t>(a), n))) {
+    if (!(p = memalign(a, n)))
         __builtin_trap();
-    }
     return p;
 }
 
-void*
-operator new[](size_t n, align_val_t a)
+static void*
+_ctl_alloc1(size_t n)
 {
-    return operator new(n, a);
-}
-void*
-operator new(size_t n)
-{
-    return operator new(n, a1);
-}
-void*
-operator new[](size_t n)
-{
-    return operator new(n, a1);
+    return _ctl_alloc(n, 1);
 }
 
-void*
-operator new(size_t, void* p)
-{
-    return p;
-}
-void*
-operator new[](size_t, void* p)
+static void*
+_ctl_ret(size_t, void* p)
 {
     return p;
 }
 
-void
-operator delete(void* p) noexcept
-{
-    free(p);
-}
-void
-operator delete[](void* p) noexcept
-{
-    free(p);
-}
-void
-operator delete(void* p, align_val_t) noexcept
-{
-    free(p);
-}
-void
-operator delete[](void* p, align_val_t) noexcept
-{
-    free(p);
-}
-void
-operator delete(void* p, size_t) noexcept
-{
-    free(p);
-}
-void
-operator delete[](void* p, size_t) noexcept
-{
-    free(p);
-}
-void
-operator delete(void* p, size_t, align_val_t) noexcept
-{
-    free(p);
-}
-void
-operator delete[](void* p, size_t, align_val_t) noexcept
+static void
+_ctl_free(void* p)
 {
     free(p);
 }
 
-void
-operator delete(void*, void*) noexcept
-{
-}
-void
-operator delete[](void*, void*) noexcept
+static void
+_ctl_nop(void*, void*)
 {
 }
+
+COSMOPOLITAN_C_END_
+
+#undef __weak_reference
+#define __weak_reference(P, A) P __attribute__((weak, alias(#A)))
+
+/* The ISO says that these should be replaceable by user code. It also says
+   that the declarations for the first four (i.e. non placement-) operators
+   new are implicitly available in each translation unit, including the std
+   align_val_t parameter. (?) However, <new> also _defines_ the align_val_t
+   type so you can’t just write your own. Our way through this morass is to
+   supply ours as ctl::align_val_t and not implicitly declare anything, for
+   now. If you have any brain cells left after reading this comment then go
+   look at the eight operator delete weak references to free in the below. */
+
+__weak_reference(void* operator new(size_t, ctl::align_val_t), _ctl_alloc);
+__weak_reference(void* operator new[](size_t, ctl::align_val_t), _ctl_alloc);
+__weak_reference(void* operator new(size_t), _ctl_alloc1);
+__weak_reference(void* operator new[](size_t), _ctl_alloc1);
+
+// XXX clang-format currently mutilates these for some reason.
+// clang-format off
+
+__weak_reference(void* operator new(size_t, void*), _ctl_ret);
+__weak_reference(void* operator new[](size_t, void*), _ctl_ret);
+
+__weak_reference(void operator delete(void*) noexcept, _ctl_free);
+__weak_reference(void operator delete[](void*) noexcept, _ctl_free);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wattribute-alias="
+__weak_reference(void operator delete(void*, ctl::align_val_t) noexcept,
+                 _ctl_free);
+__weak_reference(void operator delete[](void*, ctl::align_val_t) noexcept,
+                 _ctl_free);
+__weak_reference(void operator delete(void*, size_t) noexcept, _ctl_free);
+__weak_reference(void operator delete[](void*, size_t) noexcept, _ctl_free);
+__weak_reference(void operator delete(void*, size_t, ctl::align_val_t) noexcept,
+                 _ctl_free);
+__weak_reference(void operator delete[](void*, size_t, ctl::align_val_t)
+                 noexcept, _ctl_free);
+#pragma GCC diagnostic pop
+
+__weak_reference(void operator delete(void*, void*) noexcept, _ctl_nop);
+__weak_reference(void operator delete[](void*, void*) noexcept, _ctl_nop);
diff --git a/ctl/new.h b/ctl/new.h
index f227270ef..97fe85ef8 100644
--- a/ctl/new.h
+++ b/ctl/new.h
@@ -3,12 +3,11 @@
 #ifndef COSMOPOLITAN_CTL_NEW_H_
 #define COSMOPOLITAN_CTL_NEW_H_
 
-// XXX clang-format currently mutilates these for some reason.
-// clang-format off
-
 namespace ctl {
 
-enum class align_val_t : size_t {};
+enum class align_val_t : size_t
+{
+};
 
 } // namespace ctl
 
@@ -16,6 +15,10 @@ void* operator new(size_t);
 void* operator new[](size_t);
 void* operator new(size_t, ctl::align_val_t);
 void* operator new[](size_t, ctl::align_val_t);
+
+// XXX clang-format currently mutilates these for some reason.
+// clang-format off
+
 void* operator new(size_t, void*);
 void* operator new[](size_t, void*);