fix: early nil return #360

BhautikChudasama · 2025-08-08T07:56:23Z

Issue

getFieldProducersForFuncReturns fn would exit too early if it encountered even a single non-nilable field.
Upgraded golang to 1.24.0.
I simplified below code, Because i don't get if strings.HasPrefix(pass.Pkg.Path(), config.NilAwayPkgPathPrefix) {

	// Construct experimental features. By default, enable all features on NilAway itself.
	functionConfig := assertiontree.FunctionConfig{}
	if strings.HasPrefix(pass.Pkg.Path(), config.NilAwayPkgPathPrefix) { //nolint:revive
		// TODO: enable struct initialization flag (tracked in Issue #23).
		// TODO: enable anonymous function flag.
	} else {
		functionConfig.EnableStructInitCheck = conf.ExperimentalStructInitEnable
		functionConfig.EnableAnonymousFunc = conf.ExperimentalAnonymousFuncEnable
	}

I tried with below code

package main

import (
	"fmt"
	"math/rand"
)

type A struct {
	Name string
	Age  *int
}

func getAge() *int {
	// randomly return nil or value based on rand
	a := rand.Intn(2)
	if a == 0 {
		return nil
	}
	return &a
}

func GetA() A {
	return A{
		Name: "John",
		Age:  getAge(),
	}
}

func main() {
	fmt.Println("Hello, World!")
	var t *string = nil
	fmt.Println(*t)

	a := GetA()
	fmt.Println(*a.Age)
}

It works well.

➜ ./bin/nilaway -include-pkgs=go.uber.org/nilaway/a -experimental-struct-init=true ./a
/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:32:15: error: Potential nil panic detected. Observed nil flow from source to dereference point: 
        - a/a.go:32:15: literal `nil` dereferenced via the assignment(s):
                - `nil` to `t` at a/a.go:31:6

/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:35:15: error: Potential nil panic detected. Observed nil flow from source to dereference point: 
        - a/a.go:17:10: literal `nil` returned from `getAge()` in position 0
        - a/a.go:23:9: result 0 of `getAge()` field `Age` returned by result 0 of `GetA()`
        - a/a.go:35:15: field `Age` of result 0 of `GetA()` dereferenced

Issue: #359

CLAassistant · 2025-08-08T07:56:29Z

All committers have signed the CLA.

yuxincs · 2025-08-20T01:00:22Z

assertion/function/analyzer.go

-	// Construct experimental features. By default, enable all features on NilAway itself.
-	functionConfig := assertiontree.FunctionConfig{}
-	if strings.HasPrefix(pass.Pkg.Path(), config.NilAwayPkgPathPrefix) { //nolint:revive
-		// TODO: enable struct initialization flag (tracked in Issue #23).
-		// TODO: enable anonymous function flag.
-	} else {
-		functionConfig.EnableStructInitCheck = conf.ExperimentalStructInitEnable
-		functionConfig.EnableAnonymousFunc = conf.ExperimentalAnonymousFuncEnable
-	}
+    // Respect driver flags for experimental features for all packages.
+    functionConfig := assertiontree.FunctionConfig{
+        EnableStructInitCheck: conf.ExperimentalStructInitEnable,
+        EnableAnonymousFunc:   conf.ExperimentalAnonymousFuncEnable,
+    }


This was there such that we can enable these experimental features on NilAway itself (to dogfood), but now that we have exposed these as proper flags we can do that at CLI level instead of hard coding it.

Thanks!

yuxincs · 2025-08-20T01:01:09Z

.tool-version

@@ -0,0 +1 @@
+golang 1.24.0


Can we remove these changes? Usually minimum Go version upgrades should be put in separate PRs where we also update CI configs, use new language features etc.

yuxincs · 2025-08-20T01:01:15Z

go.mod

-go 1.23.0
-
-toolchain go1.23.4
+go 1.24.0


Same as above

yuxincs · 2025-08-20T01:01:47Z

@BhautikChudasama Thanks for the contributions! I have left some comments here :)

Also, please run make lint (or make lint-fix to directly apply fixes) to lint and format the codebase such that CI can pass

codecov · 2025-08-20T01:10:21Z

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.63%. Comparing base (8ad05f0) to head (e3b5190).

Files with missing lines	Patch %	Lines
...ssertion/function/assertiontree/structinit_util.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #360      +/-   ##
==========================================
+ Coverage   87.59%   87.63%   +0.04%     
==========================================
  Files          73       73              
  Lines       10848    10844       -4     
==========================================
+ Hits         9502     9503       +1     
+ Misses       1156     1153       -3     
+ Partials      190      188       -2

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

github-actions · 2025-08-20T01:10:37Z

Golden Test

Note

✅ NilAway errors reported on standard libraries are identical.

2527 errors on base branch (main, 8ad05f0)
2527 errors on test branch (56c3911)

BhautikChudasama · 2025-08-25T03:56:48Z

Hey @yuxincs sorry for late reply, I will update my PR. Thanks :)

BhautikChudasama · 2025-08-30T11:21:53Z

hey @yuxincs i was experimenting with some files but it is still flaky. I tried to put my head but i couldn’t really get into. If you can help here.

here is the example

// a.go
package a

import (
	"fmt"

	"go.uber.org/nilaway/database"
	"go.uber.org/nilaway/models"
)

func main() {
	db, err := database.GetPostgresqlConnection("your_connection_string_here")
	if err != nil {
		fmt.Println("Error connecting to database:", err)
		return
	}

	deploymentItem, err := models.GetDeploymentItem(db, "aa")
	fmt.Println(deploymentItem.Id)
	fmt.Println(*deploymentItem.Col1)
	fmt.Println(string(*deploymentItem.Col2))
	fmt.Println(string(*deploymentItem.Col3))
	fmt.Println(string(*deploymentItem.Col4))
	fmt.Println(deploymentItem.Col5)
	fmt.Println(*deploymentItem.Col6)
	fmt.Println(string(*deploymentItem.Col7))
}

// models/deployment.go

package models

import (
	"context"
	"encoding/json"
	"errors"

	"go.uber.org/nilaway/database"
)

type DeploymentItem struct {
	Id   string           `json:"id" db:"id"`
	Col1 *string          `json:"col1" db:"col1"`
	Col2 *json.RawMessage `json:"col2" db:"col2"`
	Col3 *json.RawMessage `json:"col3" db:"col3"`
	Col4 *json.RawMessage `json:"col4" db:"col4"`
	Col5 string           `json:"col5" db:"col5"`
	Col6 *int             `json:"col6" db:"col6"`
	Col7 *json.RawMessage `json:"col7" db:"col7"`
}

func GetDeploymentItem(con *database.Db, id string) (DeploymentItem, error) {
	var deploymentItem DeploymentItem
	q, ok := con.GetQuery("getDeploymentItem")
	if !ok {
		return deploymentItem, errors.New("query not found: getDeploymentItem")
	}

	err := con.Con.QueryRow(context.Background(), q, id).Scan(&deploymentItem.Id, &deploymentItem.Col1, &deploymentItem.Col2, &deploymentItem.Col3, &deploymentItem.Col4, &deploymentItem.Col5, &deploymentItem.Col6)
	return deploymentItem, err
}

When i am trying to run this

nilaway on  main [!?] via 🐹 v1.23.5
➜ ./bin/nilaway -include-pkgs=go.uber.org/nilaway -experimental-struct-init=true -experimental-struct-init=true ./a
/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:33:15: error: Potential nil panic detected. Observed nil flow from source to dereference point:
	- models/deployment.go:44:9: uninitialized field `Col1` returned by result 0 of `GetDeploymentItem()`
	- a/a.go:33:15: field `Col1` of result 0 of `GetDeploymentItem()` dereferenced

/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:35:22: error: Potential nil panic detected. Observed nil flow from source to dereference point:
	- models/deployment.go:44:9: uninitialized field `Col3` returned by result 0 of `GetDeploymentItem()`
	- a/a.go:35:22: field `Col3` of result 0 of `GetDeploymentItem()` dereferenced

/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:38:15: error: Potential nil panic detected. Observed nil flow from source to dereference point:
	- models/deployment.go:44:9: uninitialized field `Col6` returned by result 0 of `GetDeploymentItem()`
	- a/a.go:38:15: field `Col6` of result 0 of `GetDeploymentItem()` dereferenced

/Users/bhautik/workspace/src/experiments/nilaway/a/a.go:39:22: error: Potential nil panic detected. Observed nil flow from source to dereference point:
	- models/deployment.go:44:9: uninitialized field `Col7` returned by result 0 of `GetDeploymentItem()`
	- a/a.go:39:22: field `Col7` of result 0 of `GetDeploymentItem()` dereferenced

Expected it should return Col2 as well.

fix: early nil return

e3b5190

yuxincs reviewed Aug 20, 2025

View reviewed changes

go.mod

go 1.23.0

toolchain go1.23.4

go 1.24.0

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