Extract generics

.github/workflows/codeqltest.yml

@@ -7,10 +7,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.17
+    - name: Set up Go 1.18.1
       uses: actions/setup-go@v1
       with:
-        go-version: 1.17
+        go-version: 1.18.1
       id: go
 
     - name: Set up CodeQL CLI
@@ -59,10 +59,10 @@ jobs:
     name: Test MacOS
     runs-on: macOS-latest
     steps:
-    - name: Set up Go 1.17
+    - name: Set up Go 1.18.1
       uses: actions/setup-go@v1
       with:
-        go-version: 1.17
+        go-version: 1.18.1
       id: go
 
     - name: Set up CodeQL CLI
@@ -99,10 +99,10 @@ jobs:
     name: Test Windows
     runs-on: windows-2019
     steps:
-    - name: Set up Go 1.17
+    - name: Set up Go 1.18.1
       uses: actions/setup-go@v1
       with:
-        go-version: 1.17
+        go-version: 1.18.1
       id: go
 
     - name: Set up CodeQL CLI

downgrades/90fa7836e0a239f69bbebffcf342e92c240d54bc/exprs.ql

@@ -0,0 +1,41 @@
+class Expr_ extends @expr {
+  string toString() { result = "Expr" }
+}
+
+class ExprParent_ extends @exprparent {
+  string toString() { result = "ExprParent" }
+}
+
+/**
+ * Two new kinds have been inserted such that `@sliceexpr` which used to have
+ * index 13 now has index 15. Another new kind has been inserted such that
+ * `@plusexpr` which used to have index 23 now has index 26. Entries with
+ * indices lower than 13 are unchanged.
+ */
+bindingset[new_index]
+int old_index(int new_index) {
+  if new_index < 13
+  then result = new_index
+  else
+    if new_index = [13, 14]
+    then result = 0 // badexpr
+    else
+      if new_index < 23
+      then result + (15 - 13) = new_index
+      else
+        if new_index = 23
+        then result = 0 // badexpr
+        else result + (26 - 23) = new_index
+}
+
+// The schema for exprs is:
+//
+// exprs(unique int id: @expr,
+//     int kind: int ref,
+//     int parent: @exprparent ref,
+//     int idx: int ref);
+from Expr_ expr, int new_kind, ExprParent_ parent, int idx, int old_kind
+where
+  exprs(expr, new_kind, parent, idx) and
+  old_kind = old_index(new_kind)
+select expr, old_kind, parent, idx