Add AstNode.getCanonicalQlClass and use it in PrintAst

This gives those classes satisfied by an AstNode that are considered useful for developer understanding, cf. getAQlClass which returns all satisfied classes and hides overridden ones, even if they are interesting.

Author: smowton

ql/src/semmle/go/AST.qll

@@ -45,6 +45,12 @@ class AstNode extends @node, Locatable {
   /** Gets the innermost function definition to which this AST node belongs, if any. */
   FuncDef getEnclosingFunction() { result = getParent().parentInSameFunction*() }
 
+  /**
+   * Describes important CodeQL classes for this node. May
+   * return multiple values.
+   */
+  string describeQlClass() { result = "???" }
+
   override string toString() { result = "AST node" }
 }
 

ql/src/semmle/go/Comments.qll

@@ -27,6 +27,8 @@ class Comment extends @comment, AstNode {
   CommentGroup getGroup() { this = result.getAComment() }
 
   override string toString() { result = "comment" }
+
+  override string describeQlClass() { result = "Comment" }
 }
 
 /**
@@ -59,6 +61,8 @@ class CommentGroup extends @comment_group, AstNode {
   int getNumComment() { result = count(getAComment()) }
 
   override string toString() { result = "comment group" }
+
+  override string describeQlClass() { result = "CommentGroup" }
 }
 
 /**
@@ -109,6 +113,8 @@ class DocComment extends CommentGroup {
 
   /** Gets the program element documented by this comment group. */
   Documentable getDocumentedElement() { result = node }
+
+  override string describeQlClass() { result = "DocComment" }
 }
 
 /**
@@ -120,7 +126,9 @@ class DocComment extends CommentGroup {
  * // Single line comment
  * ```
  */
-class SlashSlashComment extends @slashslashcomment, Comment { }
+class SlashSlashComment extends @slashslashcomment, Comment {
+  override string describeQlClass() { result = "SlashSlashComment" }
+}
 
 /**
  * A block comment starting with `/*` and ending with <code>*&#47;</code>.
@@ -132,7 +140,9 @@ class SlashSlashComment extends @slashslashcomment, Comment { }
  *   comment *&#47
  * </pre>
  */
-class SlashStarComment extends @slashstarcomment, Comment { }
+class SlashStarComment extends @slashstarcomment, Comment {
+  override string describeQlClass() { result = "SlashStarComment" }
+}
 
 /**
  * A single-line comment starting with `//`.
@@ -194,4 +204,6 @@ class BuildConstraintComment extends LineComment {
     // comment text starts with `+build`
     getText().regexpMatch("\\s*\\+build.*")
   }
+
+  override string describeQlClass() { result = "BuildConstraintComment" }
 }

ql/src/semmle/go/Decls.qll

@@ -30,6 +30,8 @@ class Decl extends @decl, ExprParent, StmtParent {
  */
 class BadDecl extends @baddecl, Decl {
   override string toString() { result = "bad declaration" }
+
+  override string describeQlClass() { result = "BadDecl" }
 }
 
 /**
@@ -46,34 +48,44 @@ class GenDecl extends @gendecl, Decl, Documentable {
   int getNumSpec() { result = count(getASpec()) }
 
   override predicate mayHaveSideEffects() { getASpec().mayHaveSideEffects() }
+
+  override string describeQlClass() { result = "GenDecl" }
 }
 
 /**
  * An import declaration.
  */
 class ImportDecl extends @importdecl, GenDecl {
   override string toString() { result = "import declaration" }
+
+  override string describeQlClass() { result = "ImportDecl" }
 }
 
 /**
  * A constant declaration.
  */
 class ConstDecl extends @constdecl, GenDecl {
   override string toString() { result = "constant declaration" }
+
+  override string describeQlClass() { result = "ConstDecl" }
 }
 
 /**
  * A type declaration.
  */
 class TypeDecl extends @typedecl, GenDecl {
   override string toString() { result = "type declaration" }
+
+  override string describeQlClass() { result = "TypeDecl" }
 }
 
 /**
  * A variable declaration.
  */
 class VarDecl extends @vardecl, GenDecl {
   override string toString() { result = "variable declaration" }
+
+  override string describeQlClass() { result = "VarDecl" }
 }
 
 /**
@@ -133,6 +145,8 @@ class FuncDef extends @funcdef, StmtParent, ExprParent {
    * Gets a call to this function.
    */
   DataFlow::CallNode getACall() { result.getACallee() = this }
+
+  override string describeQlClass() { result = "FuncDef" }
 }
 
 /**
@@ -155,6 +169,8 @@ class FuncDecl extends @funcdecl, Decl, Documentable, FuncDef {
   DeclaredFunction getFunction() { this = result.getFuncDecl() }
 
   override string toString() { result = "function declaration" }
+
+  override string describeQlClass() { result = "FuncDecl" }
 }
 
 /**
@@ -219,6 +235,8 @@ class MethodDecl extends FuncDecl {
    * is the variable `p`.
    */
   ReceiverVariable getReceiver() { result.getFunction() = this }
+
+  override string describeQlClass() { result = "MethodDecl" }
 }
 
 /**
@@ -243,6 +261,8 @@ class Spec extends @spec, ExprParent, Documentable {
    * Memory allocation is not considered an observable side effect.
    */
   predicate mayHaveSideEffects() { none() }
+
+  override string describeQlClass() { result = "Spec" }
 }
 
 /**
@@ -262,6 +282,8 @@ class ImportSpec extends @importspec, Spec {
   string getPath() { result = getPathExpr().getValue() }
 
   override string toString() { result = "import specifier" }
+
+  override string describeQlClass() { result = "ImportSpec" }
 }
 
 /**
@@ -344,6 +366,8 @@ class ValueSpec extends @valuespec, Spec {
   override predicate mayHaveSideEffects() { getAnInit().mayHaveSideEffects() }
 
   override string toString() { result = "value declaration specifier" }
+
+  override string describeQlClass() { result = "ValueSpec" }
 }
 
 /**
@@ -360,6 +384,8 @@ class TypeSpec extends @typespec, Spec {
   Expr getTypeExpr() { result = getChildExpr(1) }
 
   override string toString() { result = "type declaration specifier" }
+
+  override string describeQlClass() { result = "TypeSpec" }
 }
 
 /**
@@ -397,13 +423,17 @@ class FieldDecl extends @field, Documentable, ExprParent {
   StructType getDeclaringType() { result = getDeclaringStructTypeExpr().getType() }
 
   override string toString() { result = "field declaration" }
+
+  override string describeQlClass() { result = "FieldDecl" }
 }
 
 /**
  * An embedded field declaration in a struct.
  */
 class EmbeddedFieldDecl extends FieldDecl {
   EmbeddedFieldDecl() { not exists(this.getNameExpr(_)) }
+
+  override string describeQlClass() { result = "EmbeddedFieldDecl" }
 }
 
 /**
@@ -453,6 +483,8 @@ class ParameterDecl extends @field, Documentable, ExprParent {
   }
 
   override string toString() { result = "parameter declaration" }
+
+  override string describeQlClass() { result = "ParameterDecl" }
 }
 
 /**
@@ -482,6 +514,8 @@ class ReceiverDecl extends @field, Documentable, ExprParent {
   Expr getNameExpr() { result = getChildExpr(1) }
 
   override string toString() { result = "receiver declaration" }
+
+  override string describeQlClass() { result = "ReceiverDecl" }
 }
 
 /**
@@ -531,6 +565,8 @@ class ResultVariableDecl extends @field, Documentable, ExprParent {
   int getIndex() { fields(this, _, -(result + 1)) }
 
   override string toString() { result = "result variable declaration" }
+
+  override string describeQlClass() { result = "ResultVariableDecl" }
 }
 
 /**
@@ -579,6 +615,8 @@ class MethodSpec extends InterfaceMemberSpec {
   Expr getNameExpr() { result = name }
 
   override string toString() { result = "method declaration" }
+
+  override string describeQlClass() { result = "MethodSpec" }
 }
 
 /**
@@ -588,4 +626,6 @@ class EmbeddingSpec extends InterfaceMemberSpec {
   EmbeddingSpec() { not exists(getChildExpr(1)) }
 
   override string toString() { result = "interface embedding" }
+
+  override string describeQlClass() { result = "EmbeddingSpec" }
 }