Extract generic function instantiations to new table

extractor/dbscheme/tables.go

@@ -371,9 +371,15 @@ var ParenExpr = ExprKind.NewBranch("@parenexpr")
 // SelectorExpr is the type of selector expression AST nodes
 var SelectorExpr = ExprKind.NewBranch("@selectorexpr")
 
-// IndexExpr is the type of index expression AST nodes
+// IndexExpr is the type of index expression AST nodes which are not generic type
+// instantiation expressions
 var IndexExpr = ExprKind.NewBranch("@indexexpr")
 
+// GenericFunctionInstantiationExpr is the type of AST nodes that represent a instantiation
+// of a generic type. These correspond to some index expression AST nodes and all index
+// list expression AST nodes.
+var GenericFunctionInstantiationExpr = ExprKind.NewBranch("@genericfunctioninstantiationexpr")
+
 // SliceExpr is the type of slice expression AST nodes
 var SliceExpr = ExprKind.NewBranch("@sliceexpr")
 

extractor/extractor.go

@@ -877,9 +877,24 @@ func extractExpr(tw *trap.Writer, expr ast.Expr, parent trap.Label, idx int) {
 		if expr == nil {
 			return
 		}
-		kind = dbscheme.IndexExpr.Index()
+		switch tp := tw.Package.TypesInfo.TypeOf(expr.X).Underlying().(type) {
+		case *types.Signature:
+			kind = dbscheme.GenericFunctionInstantiationExpr.Index()
+		case *types.Map, *types.Array, *types.Slice, *types.Basic, *types.Pointer:
+			// map, array, slice, string or pointer to array
+			kind = dbscheme.IndexExpr.Index()
+		default:
+			log.Fatalf("unsupported IndexExpr: its base expression is a %s.", tp.String())
+		}
 		extractExpr(tw, expr.X, lbl, 0)
 		extractExpr(tw, expr.Index, lbl, 1)
+	case *ast.IndexListExpr:
+		if expr == nil {
+			return
+		}
+		kind = dbscheme.GenericFunctionInstantiationExpr.Index()
+		extractExpr(tw, expr.X, lbl, 0)
+		extractExprs(tw, expr.Indices, lbl, 1, 1)
 	case *ast.SliceExpr:
 		if expr == nil {
 			return

ql/lib/go.dbscheme

@@ -272,46 +272,47 @@ case @expr.kind of
 | 10 = @parenexpr
 | 11 = @selectorexpr
 | 12 = @indexexpr
-| 13 = @sliceexpr
-| 14 = @typeassertexpr
-| 15 = @callorconversionexpr
-| 16 = @starexpr
-| 17 = @keyvalueexpr
-| 18 = @arraytypeexpr
-| 19 = @structtypeexpr
-| 20 = @functypeexpr
-| 21 = @interfacetypeexpr
-| 22 = @maptypeexpr
-| 23 = @plusexpr
-| 24 = @minusexpr
-| 25 = @notexpr
-| 26 = @complementexpr
-| 27 = @derefexpr
-| 28 = @addressexpr
-| 29 = @arrowexpr
-| 30 = @lorexpr
-| 31 = @landexpr
-| 32 = @eqlexpr
-| 33 = @neqexpr
-| 34 = @lssexpr
-| 35 = @leqexpr
-| 36 = @gtrexpr
-| 37 = @geqexpr
-| 38 = @addexpr
-| 39 = @subexpr
-| 40 = @orexpr
-| 41 = @xorexpr
-| 42 = @mulexpr
-| 43 = @quoexpr
-| 44 = @remexpr
-| 45 = @shlexpr
-| 46 = @shrexpr
-| 47 = @andexpr
-| 48 = @andnotexpr
-| 49 = @sendchantypeexpr
-| 50 = @recvchantypeexpr
-| 51 = @sendrcvchantypeexpr
-| 52 = @errorexpr;
+| 13 = @genericfunctioninstantiationexpr
+| 14 = @sliceexpr
+| 15 = @typeassertexpr
+| 16 = @callorconversionexpr
+| 17 = @starexpr
+| 18 = @keyvalueexpr
+| 19 = @arraytypeexpr
+| 20 = @structtypeexpr
+| 21 = @functypeexpr
+| 22 = @interfacetypeexpr
+| 23 = @maptypeexpr
+| 24 = @plusexpr
+| 25 = @minusexpr
+| 26 = @notexpr
+| 27 = @complementexpr
+| 28 = @derefexpr
+| 29 = @addressexpr
+| 30 = @arrowexpr
+| 31 = @lorexpr
+| 32 = @landexpr
+| 33 = @eqlexpr
+| 34 = @neqexpr
+| 35 = @lssexpr
+| 36 = @leqexpr
+| 37 = @gtrexpr
+| 38 = @geqexpr
+| 39 = @addexpr
+| 40 = @subexpr
+| 41 = @orexpr
+| 42 = @xorexpr
+| 43 = @mulexpr
+| 44 = @quoexpr
+| 45 = @remexpr
+| 46 = @shlexpr
+| 47 = @shrexpr
+| 48 = @andexpr
+| 49 = @andnotexpr
+| 50 = @sendchantypeexpr
+| 51 = @recvchantypeexpr
+| 52 = @sendrcvchantypeexpr
+| 53 = @errorexpr;
 
 @basiclit = @intlit | @floatlit | @imaglit | @charlit | @stringlit;
 

ql/lib/semmle/go/Expr.qll

@@ -626,11 +626,16 @@ class PromotedSelector extends SelectorExpr {
 
 /**
  * An index expression, that is, a base expression followed by an index.
+ * Expressions which represent generic type instantiations have been
+ * excluded.
  *
  * Examples:
  *
  * ```go
- * a[i]
+ * array[i]
+ * arrayptr[i]
+ * slice[i]
+ * map[key]
  * ```
  */
 class IndexExpr extends @indexexpr, Expr {
@@ -647,6 +652,34 @@ class IndexExpr extends @indexexpr, Expr {
   override string getAPrimaryQlClass() { result = "IndexExpr" }
 }
 
+/**
+ * A generic function instantiation, that is, a base expression that represents
+ * a generic function, followed by a list of type arguments.
+ *
+ * Examples:
+ *
+ * ```go
+ * genericfunction[type]
+ * genericfunction[type1, type2]
+ * ```
+ */
+class GenericFunctionInstantiationExpr extends @genericfunctioninstantiationexpr, Expr {
+  /** Gets the generic type expression. */
+  Expr getBase() { result = this.getChildExpr(0) }
+
+  /** Gets the `i`th type argument. */
+  Expr getTypeArgument(int i) {
+    i >= 0 and
+    result = this.getChildExpr(i + 1)
+  }
+
+  override predicate mayHaveOwnSideEffects() { any() }
+
+  override string toString() { result = "generic function instantiation expression" }
+
+  override string getAPrimaryQlClass() { result = "GenericFunctionInstantiationExpr" }
+}
+
 /**
  * A slice expression, that is, a base expression followed by slice indices.
  *
@@ -797,11 +830,16 @@ class CallExpr extends CallOrConversionExpr {
       result = callee.(Ident).getName()
       or
       result = callee.(SelectorExpr).getSelector().getName()
+      or
+      result = callee.(GenericFunctionInstantiationExpr).getBase().(Ident).getName()
     )
   }
 
   /** Gets the declared target of this call. */
-  Function getTarget() { this.getCalleeExpr() = result.getAReference() }
+  Function getTarget() {
+    this.getCalleeExpr() = result.getAReference() or
+    this.getCalleeExpr().(GenericFunctionInstantiationExpr).getBase() = result.getAReference()
+  }
 
   /** Holds if this call has an ellipsis after its last argument. */
   predicate hasEllipsis() { has_ellipsis(this) }