From c6a52ed2eaed308896e37df8e8bbf5e02d01b68f Mon Sep 17 00:00:00 2001
From: Taus <tausbn@github.com>
Date: Thu, 14 Oct 2021 15:44:23 +0000
Subject: [PATCH 1/2] Query: Noninitial imports of the standard library

Finds a single result in

```
semmle.code.java.dataflow.internal.rangeanalysis.SignAnalysisSpecific.qll
```
which starts with

```ql
module Private {
  import semmle.code.java.dataflow.RangeUtils as RU
  private import semmle.code.java.dataflow.SSA as Ssa
  private import semmle.code.java.controlflow.Guards as G
  private import java as J
  private import Sign
  ...
```
---
 .../performance/NonInitialStdLibImport.ql     | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 ql/src/queries/performance/NonInitialStdLibImport.ql

diff --git a/ql/src/queries/performance/NonInitialStdLibImport.ql b/ql/src/queries/performance/NonInitialStdLibImport.ql
new file mode 100644
index 00000000000..831e1df789d
--- /dev/null
+++ b/ql/src/queries/performance/NonInitialStdLibImport.ql
@@ -0,0 +1,30 @@
+/**
+ * @name Standard library is not the first import
+ * @description Importing other libraries before the standard library can cause a change in
+ *              evaluation order and may lead to performance errors.
+ * @kind problem
+ * @problem.severity error
+ * @id ql/noninitial-stdlib-import
+ * @tags performance
+ * @precision high
+ */
+
+import ql
+
+predicate isStdLibImport(Import i, string name) {
+  name = i.getQualifiedName(0) and
+  i.getLocation().getFile().getRelativePath().matches(name + "%") and
+  not exists(i.getQualifiedName(1))
+}
+
+Import importBefore(Import i) {
+  exists(Module m, int bi, int ii |
+    result = m.getMember(bi) and
+    i = m.getMember(ii) and
+    bi < ii
+    )
+}
+
+from Import i
+where isStdLibImport(i, _) and exists(importBefore(i))
+select i, "This import may cause reevaluation to occur, as there are other imports preceding it"

From 71f69997e29bc6308813b996dda817c1fa767923 Mon Sep 17 00:00:00 2001
From: Taus <tausbn@github.com>
Date: Thu, 14 Oct 2021 16:06:19 +0000
Subject: [PATCH 2/2] Autoformat

---
 ql/src/queries/performance/NonInitialStdLibImport.ql | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ql/src/queries/performance/NonInitialStdLibImport.ql b/ql/src/queries/performance/NonInitialStdLibImport.ql
index 831e1df789d..88296d895fc 100644
--- a/ql/src/queries/performance/NonInitialStdLibImport.ql
+++ b/ql/src/queries/performance/NonInitialStdLibImport.ql
@@ -22,7 +22,7 @@ Import importBefore(Import i) {
     result = m.getMember(bi) and
     i = m.getMember(ii) and
     bi < ii
-    )
+  )
 }
 
 from Import i