From a5d9d0157eb5293ca670935c69f56d23321f696d Mon Sep 17 00:00:00 2001
From: Richard Yao <richard.yao@alumni.stonybrook.edu>
Date: Sun, 21 Jan 2024 12:26:22 -0500
Subject: [PATCH] Add CodeQL query to detect redundant assignments

Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
---
 .github/codeql-cpp.yml                         |  4 ++++
 .github/codeql-python.yml                      |  4 ++++
 .github/codeql/custom-queries/cpp/qlpack.yml   |  8 ++++++++
 .../custom-queries/cpp/redundantAssignment.ql  | 18 ++++++++++++++++++
 .github/workflows/codeql.yml                   |  1 +
 5 files changed, 35 insertions(+)
 create mode 100644 .github/codeql-cpp.yml
 create mode 100644 .github/codeql-python.yml
 create mode 100644 .github/codeql/custom-queries/cpp/qlpack.yml
 create mode 100644 .github/codeql/custom-queries/cpp/redundantAssignment.ql

diff --git a/.github/codeql-cpp.yml b/.github/codeql-cpp.yml
new file mode 100644
index 000000000000..41aeac1f83d0
--- /dev/null
+++ b/.github/codeql-cpp.yml
@@ -0,0 +1,4 @@
+name: "Custom CodeQL Analysis"
+
+queries:
+  - uses: ./.github/codeql/custom-queries/cpp/redundantAssignment.ql
diff --git a/.github/codeql-python.yml b/.github/codeql-python.yml
new file mode 100644
index 000000000000..93cb4a435ed9
--- /dev/null
+++ b/.github/codeql-python.yml
@@ -0,0 +1,4 @@
+name: "Custom CodeQL Analysis"
+
+paths-ignore:
+  - tests
diff --git a/.github/codeql/custom-queries/cpp/qlpack.yml b/.github/codeql/custom-queries/cpp/qlpack.yml
new file mode 100644
index 000000000000..65fee66ad075
--- /dev/null
+++ b/.github/codeql/custom-queries/cpp/qlpack.yml
@@ -0,0 +1,8 @@
+name: cpp-custom-queries
+version: 0.0.1
+library: false
+groups:
+  - cpp
+  - examples
+dependencies:
+  codeql/cpp-all: ${workspace}
diff --git a/.github/codeql/custom-queries/cpp/redundantAssignment.ql b/.github/codeql/custom-queries/cpp/redundantAssignment.ql
new file mode 100644
index 000000000000..37876aa15012
--- /dev/null
+++ b/.github/codeql/custom-queries/cpp/redundantAssignment.ql
@@ -0,0 +1,18 @@
+import cpp
+
+from AssignExpr firstAssign, AssignExpr secondAssign
+where
+  // The first assignment is from 'a' to 'b'
+  firstAssign.getDest().(VarAccess).getTarget() = secondAssign.getSource().(VarAccess).getTarget() and
+  firstAssign.getSource().(VarAccess).getTarget() = secondAssign.getDest().(VarAccess).getTarget() and
+  // Ensure 'a' and 'b' are not modified in between these assignments
+  not exists(Expr anyExpr |
+    anyExpr.getEnclosingFunction() = firstAssign.getEnclosingFunction() and
+    anyExpr.isBetween(firstAssign, secondAssign) and
+    (
+      anyExpr.(AssignExpr).getDest().(VarAccess).getTarget() = firstAssign.getDest().(VarAccess).getTarget() or
+      anyExpr.(AssignExpr).getDest().(VarAccess).getTarget() = firstAssign.getSource().(VarAccess).getTarget()
+    )
+  )
+select secondAssign, "This assignment is redundant."
+
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 037f8aca0eaa..7ccfc1492564 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -29,6 +29,7 @@ jobs:
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v2
       with:
+        config-file: .github/codeql-${{ matrix.language }}.yml
         languages: ${{ matrix.language }}
 
     - name: Autobuild