Extract type param declarations

extractor/dbscheme/tables.go

@@ -275,6 +275,9 @@ var StmtParentType = NewUnionType("@stmtparent", NodeType)
 // DeclParentType is the type of AST nodes that can have declarations as children
 var DeclParentType = NewUnionType("@declparent", NodeType)
 
+// TypeParamDeclParentType is the type of AST nodes that can have type parameter declarations as children
+var TypeParamDeclParentType = NewUnionType("@typeparamdeclparent", NodeType)
+
 // FuncDefType is the type of AST nodes that define functions, that is, function
 // declarations and function literals
 var FuncDefType = NewUnionType("@funcdef", StmtParentType, ExprParentType)
@@ -309,6 +312,9 @@ var StmtType = NewPrimaryKeyType("@stmt", ExprParentType, StmtParentType)
 // DeclType is the type of declaration AST nodes
 var DeclType = NewPrimaryKeyType("@decl", ExprParentType, StmtParentType, FieldParentType)
 
+// TypeParamDeclType is the type of type parameter declaration AST nodes
+var TypeParamDeclType = NewPrimaryKeyType("@typeparamdecl", DocumentableType, ExprParentType)
+
 // SpecType is the type of spec AST nodes
 var SpecType = NewPrimaryKeyType("@spec", ExprParentType, DocumentableType)
 
@@ -650,7 +656,7 @@ var TypeDeclType = DeclKind.NewBranch("@typedecl", GenDeclType)
 var VarDeclType = DeclKind.NewBranch("@vardecl", GenDeclType)
 
 // FuncDeclType is the type of function declaration AST nodes
-var FuncDeclType = DeclKind.NewBranch("@funcdecl", DocumentableType, FuncDefType)
+var FuncDeclType = DeclKind.NewBranch("@funcdecl", DocumentableType, FuncDefType, TypeParamDeclParentType)
 
 // SpecKind is a case type for distinguishing different kinds of declaration specification nodes
 var SpecKind = NewCaseType(SpecType, "kind")
@@ -662,7 +668,7 @@ var ImportSpecType = SpecKind.NewBranch("@importspec")
 var ValueSpecType = SpecKind.NewBranch("@valuespec")
 
 // TypeSpecType is the type of type declaration specification nodes
-var TypeSpecType = NewUnionType("@typespec")
+var TypeSpecType = NewUnionType("@typespec", TypeParamDeclParentType)
 
 // TypeDefSpecType is the type of type declaration specification nodes corresponding to type definitions
 var TypeDefSpecType = SpecKind.NewBranch("@typedefspec", TypeSpecType)
@@ -991,6 +997,13 @@ var FieldsTable = NewTable("fields",
 	IntColumn("idx"),
 )
 
+// TypeParamDeclsTable is the table defining type param declaration AST nodes
+var TypeParamDeclsTable = NewTable("typeparamdecls",
+	EntityColumn(TypeParamDeclType, "id").Key(),
+	EntityColumn(TypeParamDeclParentType, "parent"),
+	IntColumn("idx"),
+)
+
 // StmtsTable is the table defining statement AST nodes
 var StmtsTable = NewTable("stmts",
 	EntityColumn(StmtType, "id").Key(),

extractor/extractor.go

@@ -1336,6 +1336,12 @@ func extractDecl(tw *trap.Writer, decl ast.Decl, parent trap.Label, idx int) {
 		extractExpr(tw, decl.Type, lbl, 1)
 		extractStmt(tw, decl.Body, lbl, 2)
 		extractDoc(tw, decl.Doc, lbl)
+		extractTypeParamDecls(tw, decl.Type.TypeParams, lbl)
+
+		// Note that we currently don't extract any kind of declaration for
+		// receiver type parameters. There isn't an explicit declaration, but
+		// we could consider the index/indices of an IndexExpr/IndexListExpr
+		// receiver as declarations.
 	default:
 		log.Fatalf("unknown declaration of type %T", decl)
 	}
@@ -1377,6 +1383,7 @@ func extractSpec(tw *trap.Writer, spec ast.Spec, parent trap.Label, idx int) {
 			kind = dbscheme.TypeDefSpecType.Index()
 		}
 		extractExpr(tw, spec.Name, lbl, 0)
+		extractTypeParamDecls(tw, spec.TypeParams, lbl)
 		extractExpr(tw, spec.Type, lbl, 1)
 		extractDoc(tw, spec.Doc, lbl)
 	}
@@ -1798,3 +1805,26 @@ func flattenBinaryExprTree(tw *trap.Writer, e ast.Expr, parent trap.Label, idx i
 	}
 	return idx
 }
+
+func extractTypeParamDecls(tw *trap.Writer, fields *ast.FieldList, parent trap.Label) {
+	if fields == nil || fields.List == nil {
+		return
+	}
+
+	overrideTypesOfTypeSetLiterals(tw, fields)
+
+	idx := 0
+	for _, field := range fields.List {
+		lbl := tw.Labeler.LocalID(field)
+		dbscheme.TypeParamDeclsTable.Emit(tw, lbl, parent, idx)
+		extractNodeLocation(tw, field, lbl)
+		if field.Names != nil {
+			for i, name := range field.Names {
+				extractExpr(tw, name, lbl, i+1)
+			}
+		}
+		extractExpr(tw, field.Type, lbl, 0)
+		extractDoc(tw, field.Doc, lbl)
+		idx += 1
+	}
+}

ql/lib/go.dbscheme

@@ -157,6 +157,8 @@ constvalues(unique int expr: @expr ref, string value: string ref, string exact:
 
 fields(unique int id: @field, int parent: @fieldparent ref, int idx: int ref);
 
+typeparamdecls(unique int id: @typeparamdecl, int parent: @typeparamdeclparent ref, int idx: int ref);
+
 #keyset[parent, idx]
 stmts(unique int id: @stmt, int kind: int ref, int parent: @stmtparent ref, int idx: int ref);
 
@@ -231,12 +233,12 @@ typeparam(unique int tp: @typeparamtype ref, string name: string ref, int bound:
 
 @locatable = @xmllocatable | @node | @localscope;
 
-@node = @documentable | @exprparent | @modexprparent | @fieldparent | @stmtparent | @declparent | @scopenode
-      | @comment_group | @comment;
+@node = @documentable | @exprparent | @modexprparent | @fieldparent | @stmtparent | @declparent | @typeparamdeclparent
+      | @scopenode | @comment_group | @comment;
 
-@documentable = @file | @field | @spec | @gendecl | @funcdecl | @modexpr;
+@documentable = @file | @field | @typeparamdecl | @spec | @gendecl | @funcdecl | @modexpr;
 
-@exprparent = @funcdef | @file | @expr | @field | @stmt | @decl | @spec;
+@exprparent = @funcdef | @file | @expr | @field | @stmt | @decl | @typeparamdecl | @spec;
 
 @modexprparent = @file | @modexpr;
 
@@ -246,6 +248,8 @@ typeparam(unique int tp: @typeparamtype ref, string name: string ref, int bound:
 
 @declparent = @file | @declstmt;
 
+@typeparamdeclparent = @functypeexpr | @typespec;
+
 @funcdef = @funclit | @funcdecl;
 
 @scopenode = @file | @functypeexpr | @blockstmt | @ifstmt | @caseclause | @switchstmt | @commclause | @loopstmt;

ql/lib/semmle/go/AST.qll

@@ -216,6 +216,24 @@ class FieldParent extends @fieldparent, AstNode {
   int getNumFields() { result = count(getAField()) }
 }
 
+/**
+ * An AST node whose children include type parameter declarations.
+ */
+class TypeParamDeclParent extends @typeparamdeclparent, AstNode {
+  /**
+   * Gets the `i`th type parameter declaration of this node.
+   *
+   * Note that the precise indices of type parameters are considered an implementation detail
+   * and are subject to change without notice.
+   */
+  TypeParamDecl getTypeParameterDecl(int i) { typeparamdecls(result, this, i) }
+
+  /**
+   * Gets a child field of this node in the AST.
+   */
+  TypeParamDecl getATypeParameterDecl() { result = getTypeParameterDecl(_) }
+}
+
 /**
  * An AST node which may induce a scope.
  *

ql/lib/semmle/go/Decls.qll

@@ -146,7 +146,7 @@ class FuncDef extends @funcdef, StmtParent, ExprParent {
 /**
  * A function declaration.
  */
-class FuncDecl extends @funcdecl, Decl, Documentable, FuncDef {
+class FuncDecl extends @funcdecl, Decl, Documentable, FuncDef, TypeParamDeclParent {
   /** Gets the identifier denoting the name of this function. */
   Ident getNameExpr() { result = this.getChildExpr(0) }
 
@@ -376,7 +376,7 @@ class ValueSpec extends @valuespec, Spec {
  * )
  * ```
  */
-class TypeSpec extends @typespec, Spec {
+class TypeSpec extends @typespec, Spec, TypeParamDeclParent {
   /** Gets the identifier denoting the name of the declared type. */
   Ident getNameExpr() { result = this.getChildExpr(0) }
 
@@ -562,6 +562,57 @@ class ResultVariableDecl extends ParameterOrResultDecl {
   override string getAPrimaryQlClass() { result = "ResultVariableDecl" }
 }
 
+/**
+ * A type parameter declaration in a type specification.
+ */
+class TypeParamDecl extends @typeparamdecl, Documentable, ExprParent {
+  TypeParamDecl() { typeparamdecls(this, _, _) }
+
+  /**
+   * Gets the expression representing the type constraint of the type
+   * parameters in this declaration.
+   *
+   * If you want the type constraint type itself then use `getTypeConstraint`,
+   * as that wraps type set literals with implicit interface types.
+   */
+  Expr getTypeConstraintExpr() { result = this.getChildExpr(0) }
+
+  /**
+   * Gets the type constraint of the type parameters in this declaration.
+   *
+   * If the type constraint is a type set literal then it will be wrapped
+   * with an implicit interface type.
+   */
+  Type getTypeConstraint() {
+    exists(Type t | t = this.getTypeConstraintExpr().getType() |
+      if t instanceof TypeSetLiteralType
+      then result = t.(TypeSetLiteralType).getInterfaceType()
+      else result = t
+    )
+  }
+
+  /**
+   * Gets the expression representing the name of the `i`th type parameter
+   * in this declaration (0-based).
+   */
+  Expr getNameExpr(int i) {
+    i >= 0 and
+    result = this.getChildExpr(i + 1)
+  }
+
+  /**
+   * Gets the `i`th type parameter type in this declaration (0-based).
+   */
+  TypeParamType getTypeParamType(int i) {
+    i >= 0 and
+    result = this.getNameExpr(i).getType()
+  }
+
+  override string toString() { result = "type parameter declaration" }
+
+  override string getAPrimaryQlClass() { result = "TypeParamDecl" }
+}
+
 /**
  * A method or embedding specification in an interface type expression.
  */

ql/lib/semmle/go/Expr.qll

@@ -2096,6 +2096,10 @@ private predicate isTypeExprTopDown(Expr e) {
   or
   e = any(ParameterDecl pd).getTypeExpr()
   or
+  e = any(TypeParamDecl tpd).getTypeConstraintExpr()
+  or
+  e = any(TypeParamDecl tpd).getNameExpr(_)
+  or
   e = any(ReceiverDecl rd).getTypeExpr()
   or
   e = any(ResultVariableDecl rvd).getTypeExpr()