go/analysis: unindent some pieces of code

All of these were quite heavily indented for no good reason; breaking or
returning early makes the code easier to read and follow.

Change-Id: Ic539517b07604d71495277b16f1b7eb60d2e3d3c
Reviewed-on: https://go-review.googlesource.com/c/149978
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

go/analysis/passes/lostcancel/lostcancel.go

@@ -93,7 +93,9 @@ func runFunc(pass *analysis.Pass, node ast.Node) {
 		//   ctx, cancel     = context.WithCancel(...)
 		//   var ctx, cancel = context.WithCancel(...)
 		//
-		if isContextWithCancel(pass.TypesInfo, n) && isCall(stack[len(stack)-2]) {
+		if !isContextWithCancel(pass.TypesInfo, n) || !isCall(stack[len(stack)-2]) {
+			return true
+		}
 		var id *ast.Ident // id of cancel var
 		stmt := stack[len(stack)-3]
 		switch stmt := stmt.(type) {
@@ -117,8 +119,6 @@ func runFunc(pass *analysis.Pass, node ast.Node) {
 				cancelvars[v] = stmt
 			}
 		}
-		}
-
 		return true
 	})
 
@@ -179,9 +179,15 @@ func hasImport(pkg *types.Package, path string) bool {
 // isContextWithCancel reports whether n is one of the qualified identifiers
 // context.With{Cancel,Timeout,Deadline}.
 func isContextWithCancel(info *types.Info, n ast.Node) bool {
-	if sel, ok := n.(*ast.SelectorExpr); ok {
+	sel, ok := n.(*ast.SelectorExpr)
+	if !ok {
+		return false
+	}
 	switch sel.Sel.Name {
 	case "WithCancel", "WithTimeout", "WithDeadline":
+	default:
+		return false
+	}
 	if x, ok := sel.X.(*ast.Ident); ok {
 		if pkgname, ok := info.Uses[x].(*types.PkgName); ok {
 			return pkgname.Imported().Path() == contextPackage
@@ -190,8 +196,6 @@ func isContextWithCancel(info *types.Info, n ast.Node) bool {
 		// Just check the local package name (heuristic).
 		return x.Name == "context"
 	}
-		}
-	}
 	return false
 }
 
@@ -270,7 +274,9 @@ outer:
 	var search func(blocks []*cfg.Block) *ast.ReturnStmt
 	search = func(blocks []*cfg.Block) *ast.ReturnStmt {
 		for _, b := range blocks {
-			if !seen[b] {
+			if seen[b] {
+				continue
+			}
 			seen[b] = true
 
 			// Prune the search if the block uses v.
@@ -294,7 +300,6 @@ outer:
 				return ret
 			}
 		}
-		}
 		return nil
 	}
 	return search(defblock.Succs)

go/analysis/passes/unsafeptr/unsafeptr.go

@@ -62,8 +62,9 @@ func isSafeUintptr(info *types.Info, x ast.Expr) bool {
 		return isSafeUintptr(info, x.X)
 
 	case *ast.SelectorExpr:
-		switch x.Sel.Name {
-		case "Data":
+		if x.Sel.Name != "Data" {
+			break
+		}
 		// reflect.SliceHeader and reflect.StringHeader are okay,
 		// but only if they are pointing at a real slice or string.
 		// It's not okay to do:
@@ -86,7 +87,6 @@ func isSafeUintptr(info *types.Info, x ast.Expr) bool {
 				}
 			}
 		}
-		}
 
 	case *ast.CallExpr:
 		switch len(x.Args) {