dajiaohuang · Oct 1, 2026 · Oct 2, 2026
diff --git a/staticcheck/sa4026/sa4026.go b/staticcheck/sa4026/sa4026.go
@@ -2,7 +2,9 @@ package sa4026
 
 import (
 	"fmt"
+	"go/ast"
 	"go/types"
+	"strconv"
 
 	"honnef.co/go/tools/analysis/code"
 	"honnef.co/go/tools/analysis/edit"
@@ -53,26 +55,63 @@ var negativeZeroFloatQ = pattern.MustParse(`
 			(UnaryExpr "-" lit@(BasicLit "INT" "0"))))`)
 
 func run(pass *analysis.Pass) (any, error) {
+	mathQualifier := func(node ast.Node) string {
+		for _, file := range pass.Files {
+			if node.Pos() < file.Pos() || node.Pos() > file.End() {
+				continue
+			}
+			for _, spec := range file.Imports {
+				path, err := strconv.Unquote(spec.Path.Value)
+				if err != nil || path != "math" {
+					continue
+				}
+				var pkgName *types.PkgName
+				if spec.Name != nil {
+					pkgName, _ = pass.TypesInfo.Defs[spec.Name].(*types.PkgName)
+				} else {
+					pkgName, _ = pass.TypesInfo.Implicits[spec].(*types.PkgName)
+				}
+				if pkgName != nil && pkgName.Name() != "." && pkgName.Name() != "_" {
+					scope := pass.TypesInfo.Scopes[file].Innermost(node.Pos())
+					if scope != nil {
+						_, obj := scope.LookupParent(pkgName.Name(), node.Pos())
+						if obj == pkgName {
+							return pkgName.Name()
+						}
+					}
+				}
+			}
+		}
+		return ""
+	}
 	for node, m := range code.Matches(pass, negativeZeroFloatQ) {
+		mathName := mathQualifier(node)
 		if conv, ok := m.State["conv"].(*types.TypeName); ok {
 			var replacement string
 			// TODO(dh): how does this handle type aliases?
 			if conv.Name() == "float32" {
-				replacement = `float32(math.Copysign(0, -1))`
+				replacement = fmt.Sprintf(`float32(%s.Copysign(0, -1))`, mathName)
 			} else {
-				replacement = `math.Copysign(0, -1)`
+				replacement = fmt.Sprintf(`%s.Copysign(0, -1)`, mathName)
+			}
+			var opts []report.Option
+			if mathName != "" {
+				opts = append(opts, report.Fixes(edit.Fix("Use math.Copysign to create negative zero", edit.ReplaceWithString(node, replacement))))
 			}
 			report.Report(pass, node,
 				fmt.Sprintf("in Go, the floating-point expression '%s' is the same as '%s(%s)', it does not produce a negative zero",
 					report.Render(pass, node),
 					conv.Name(),
 					report.Render(pass, m.State["lit"])),
-				report.Fixes(edit.Fix("Use math.Copysign to create negative zero", edit.ReplaceWithString(node, replacement))))
+				opts...)
 		} else {
-			const replacement = `math.Copysign(0, -1)`
+			var opts []report.Option
+			if mathName != "" {
+				opts = append(opts, report.Fixes(edit.Fix("Use math.Copysign to create negative zero", edit.ReplaceWithString(node, fmt.Sprintf(`%s.Copysign(0, -1)`, mathName)))))
+			}
 			report.Report(pass, node,
 				"in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero",
-				report.Fixes(edit.Fix("Use math.Copysign to create negative zero", edit.ReplaceWithString(node, replacement))))
+				opts...)
 		}
 	}
 	return nil, nil

diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroFloat/CheckNegativeZeroFloat.go b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroFloat/CheckNegativeZeroFloat.go
@@ -1,8 +1,11 @@
 package pkg
 
+import m "math"
+
 const x = 0.0
 
 func fn() {
+	_ = m.Copysign
 	_ = -0.0          //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
 	_ = float32(-0.0) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
 	_ = float64(-0.0) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)

diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroFloat/CheckNegativeZeroFloat.go.golden b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroFloat/CheckNegativeZeroFloat.go.golden
@@ -1,15 +1,18 @@
 package pkg
 
+import m "math"
+
 const x = 0.0
 
 func fn() {
-	_ = math.Copysign(0, -1)          //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
-	_ = float32(math.Copysign(0, -1)) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
-	_ = float64(math.Copysign(0, -1)) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
-	_ = float32(math.Copysign(0, -1)) //@ diag(`in Go, the floating-point expressio
8000
n '-float32(0)' is the same as 'float32(0)', it does not produce a negative zero`)
-	_ = math.Copysign(0, -1)          //@ diag(`in Go, the floating-point expression '-float64(0)' is the same as 'float64(0)', it does not produce a negative zero`)
-	_ = float32(math.Copysign(0, -1)) //@ diag(`in Go, the floating-point expression '-float32(0.0)' is the same as 'float32(0.0)', it does not produce a negative zero`)
-	_ = math.Copysign(0, -1)          //@ diag(`in Go, the floating-point expression '-float64(0.0)' is the same as 'float64(0.0)', it does not produce a negative zero`)
+	_ = m.Copysign
+	_ = m.Copysign(0, -1)          //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
+	_ = float32(m.Copysign(0, -1)) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
+	_ = float64(m.Copysign(0, -1)) //@ diag(`in Go, the floating-point literal '-0.0' is the same as '0.0', it does not produce a negative zero`)
+	_ = float32(m.Copysign(0, -1)) //@ diag(`in Go, the floating-point expression '-float32(0)' is the same as 'float32(0)', it does not produce a negative zero`)
+	_ = m.Copysign(0, -1)          //@ diag(`in Go, the floating-point expression '-float64(0)' is the same as 'float64(0)', it does not produce a negative zero`)
+	_ = float32(m.Copysign(0, -1)) //@ diag(`in Go, the floating-point expression '-float32(0.0)' is the same as 'float32(0.0)', it does not produce a negative zero`)
+	_ = m.Copysign(0, -1)          //@ diag(`in Go, the floating-point expression '-float64(0.0)' is the same as 'float64(0.0)', it does not produce a negative zero`)
 
 	// intentionally not flagged
 	_ = -x

diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/import.go b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/import.go
@@ -0,0 +1,5 @@
+package pkg
+
+import m "math"
+
+var _ = m.Copysign
diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/import.go.golden b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/import.go.golden
@@ -0,0 +1,5 @@
+package pkg
+
+import m "math"
+
+var _ = m.Copysign
diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/other.go b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/other.go
@@ -0,0 +1,6 @@
+package pkg
+
+func other() {
+	_ = -0.0 //@ diag(`does not produce a negative zero`)
+	_ = float32(-0) //@ diag(`does not produce a negative zero`)
+}
diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/other.go.golden b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/other.go.golden
@@ -0,0 +1,6 @@
+package pkg
+
+func other() {
+	_ = -0.0 //@ diag(`does not produce a negative zero`)
+	_ = float32(-0) //@ diag(`does not produce a negative zero`)
+}
diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/shadow.go b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/shadow.go
@@ -0,0 +1,12 @@
+package pkg
+
+import m "math"
+
+var _ = m.Copysign
+
+func shadow() {
+	m := 1
+	_ = m
+	_ = -0.0 //@ diag(`does not produce a negative zero`)
+	_ = float32(-0) //@ diag(`does not produce a negative zero`)
+}
diff --git a/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/shadow.go.golden b/staticcheck/sa4026/testdata/go1.0/CheckNegativeZeroScope/shadow.go.golden
@@ -0,0 +1,12 @@
+package pkg
+
+import m "math"
+
+var _ = m.Copysign
+
+func shadow() {
+	m := 1
+	_ = m
+	_ = -0.0 //@ diag(`does not produce a negative zero`)
+	_ = float32(-0) //@ diag(`does not produce a negative zero`)
+}