Swift: DotSyntaxBaseIgnored calls now have static target

This relies on getStaticTarget() returning a Callable... Not sure how I feel about that, since often we want to say

```
exists(Call c |
  c.getStaticTarget().hasName("...")
)
```

and Callable has a sparse interface. Maybe some AbstractFunctionDecl
methods can be moved to Callable.

Author: d10c

swift/ql/lib/codeql/swift/elements/expr/ApplyExpr.qll

@@ -2,20 +2,12 @@ private import codeql.swift.generated.expr.ApplyExpr
 private import codeql.swift.elements.Callable
 private import codeql.swift.elements.expr.DeclRefExpr
 private import codeql.swift.elements.expr.MethodLookupExpr
-private import codeql.swift.elements.expr.ConstructorRefCallExpr
+private import codeql.swift.elements.expr.DotSyntaxBaseIgnoredExpr
+private import codeql.swift.elements.expr.AutoClosureExpr
 private import codeql.swift.elements.decl.MethodDecl
 
 class ApplyExpr extends Generated::ApplyExpr {
-  Callable getStaticTarget() {
-    exists(Expr f |
-      f = this.getFunction() and
-      (
-        result = f.(DeclRefExpr).getDecl()
-        or
-        result = f.(ConstructorRefCallExpr).getFunction().(DeclRefExpr).getDecl() // TODO: fix this
-      )
-    )
-  }
+  Callable getStaticTarget() { result = this.getFunction().(DeclRefExpr).getDecl() }
 
   /** Gets the method qualifier, if this is applying a method */
   Expr getQualifier() { none() }
@@ -45,3 +37,25 @@ class MethodApplyExpr extends ApplyExpr {
 
   override Expr getQualifier() { result = method.getBase() }
 }
+
+private class PartialDotSyntaxBaseIgnoredApplyExpr extends ApplyExpr {
+  private DotSyntaxBaseIgnoredExpr expr;
+
+  PartialDotSyntaxBaseIgnoredApplyExpr() { expr = this.getFunction() }
+
+  override AutoClosureExpr getStaticTarget() { result = expr.getSubExpr() }
+
+  override Expr getQualifier() { result = expr.getQualifier() }
+
+  override string toString() { result = "call to " + expr }
+}
+
+private class FullDotSyntaxBaseIgnoredApplyExpr extends ApplyExpr {
+  private PartialDotSyntaxBaseIgnoredApplyExpr expr;
+
+  FullDotSyntaxBaseIgnoredApplyExpr() { expr = this.getFunction() }
+
+  override AutoClosureExpr getStaticTarget() { result = expr.getStaticTarget().getExpr() }
+
+  override string toString() { result = "call to " + expr }
+}

swift/ql/lib/codeql/swift/elements/expr/DotSyntaxBaseIgnoredExpr.qll

@@ -1,5 +1,27 @@
 private import codeql.swift.generated.expr.DotSyntaxBaseIgnoredExpr
+private import codeql.swift.elements.expr.AutoClosureExpr
+private import codeql.swift.elements.expr.CallExpr
+private import codeql.swift.elements.expr.TypeExpr
+private import codeql.swift.elements.decl.MethodDecl
 
 class DotSyntaxBaseIgnoredExpr extends Generated::DotSyntaxBaseIgnoredExpr {
-  override string toString() { result = "." + this.getSubExpr().toString() }
+  override string toString() {
+    result =
+      concat(this.getQualifier().(TypeExpr).getTypeRepr().toString()) + "." + this.getMethod()
+  }
+
+  /**
+   * Gets the underlying instance method that is called when the result of this
+   * expression is fully applied.
+   */
+  MethodDecl getMethod() {
+    result =
+      this.getSubExpr()
+          .(AutoClosureExpr)
+          .getExpr()
+          .(AutoClosureExpr)
+          .getExpr()
+          .(CallExpr)
+          .getStaticTarget()
+  }
 }