Create rule S7427: Null pointers should not be transmuted (#4768)

* Create rule S7427

* Update RSPEC

---------

Co-authored-by: yassin-kammoun-sonarsource <yassin-kammoun-sonarsource@users.noreply.github.com>
Co-authored-by: yassin-kammoun-sonarsource <yassin.kammoun@sonarsource.com>

rules/S7427/metadata.json

@@ -0,0 +1,2 @@
+{
+}

rules/S7427/rust/metadata.json

@@ -0,0 +1,24 @@
+{
+  "title": "Null pointers should not be transmuted",
+  "type": "BUG",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+    "clippy"
+  ],
+  "defaultSeverity": "Major",
+  "ruleSpecification": "RSPEC-7427",
+  "sqKey": "S7427",
+  "scope": "All",
+  "defaultQualityProfiles": ["Sonar way"],
+  "quickfix": "unknown",
+  "code": {
+    "impacts": {
+      "RELIABILITY": "HIGH"
+    },
+    "attribute": "LOGICAL"
+  }
+}

rules/S7427/rust/rule.adoc

@@ -0,0 +1,24 @@
+== Why is this an issue?
+
+Transmuting a null pointer is undefined behavior and can lead to unpredictable program crashes and security vulnerabilities.
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,rust,diff-id=1,diff-type=noncompliant]
+----
+let null_ref: &u64 = unsafe { std::mem::transmute(0 as *const u64) }; // Noncompliant: Transmuting a null pointer.
+----
+
+==== Compliant solution
+
+[source,rust,diff-id=1,diff-type=compliant]
+----
+let null_ref: Option<&u64> = None; // Compliant: Use Option to represent nullable references.
+----
+
+== Resources
+=== Documentation
+
+* Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#transmuting_null