Silence dangling pointer warning for JS::Rooted

With much help by @sera.

libraries/source/spidermonkey/build.sh

@@ -8,7 +8,7 @@ cd "$(dirname "$0")"
 # This should match the version in config/milestone.txt
 FOLDER="mozjs-115.16.1"
 # If same-version changes are needed, increment this.
-LIB_VERSION="115.16.1+4"
+LIB_VERSION="115.16.1+5"
 LIB_NAME="mozjs115"
 
 fetch()

libraries/source/spidermonkey/patches/SupressDanglingPointerWarning.patch

@@ -0,0 +1,31 @@
+From 0bfc032c102b8a251e4dc751d0b48992ebf72641 Mon Sep 17 00:00:00 2001
+From: phosit <phosit@autistici.org>
+Date: Sun, 5 Jan 2025 14:29:33 +0100
+Subject: [PATCH] Supress -Wdangling-pointer warning on GCC
+
+---
+ js/public/RootingAPI.h | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/js/public/RootingAPI.h b/js/public/RootingAPI.h
+index 42be14e67351..6b167cb8ea2e 100644
+--- a/js/public/RootingAPI.h
++++ b/js/public/RootingAPI.h
+@@ -1166,7 +1166,14 @@ class MOZ_RAII Rooted : public detail::RootedTraits<T>::StackBase,
+   inline void registerWithRootLists(RootedListHeads& roots) {
+     this->stack = &roots[JS::MapTypeToRootKind<T>::kind];
+     this->prev = *this->stack;
++#if defined(__GNUC__) && __GNUC__ >= 12
++#pragma GCC diagnostic push
++#pragma GCC diagnostic ignored "-Wdangling-pointer"
++#endif
+     *this->stack = this;
++#if defined(__GNUC__) && __GNUC__ >= 12
++#pragma GCC diagnostic pop
++#endif
+   }
+
+   inline RootedListHeads& rootLists(RootingContext* cx) {
+--
+2.47.1
+

libraries/source/spidermonkey/patches/patch.sh

@@ -46,3 +46,6 @@ patch -p1 <"${PATCHES}"/FixPython3.12.8.diff
 # https://bugzilla.mozilla.org/show_bug.cgi?id=1876415
 # Fixed in ESR 128
 patch -p1 <"${PATCHES}"/FixProfiling.diff
+
+# Supress warning on newer GCC compilers.
+patch -p1 <"${PATCHES}"/SupressDanglingPointerWarning.patch