Imported Upstream version 1.1~hg20130304upstream/1.1_hg20130304

1 files changed, 59 insertions, 0 deletions

diff --git a/src/cmd/vet/atomic.go b/src/cmd/vet/atomic.go
new file mode 100644
index 000000000..4ab256f64
--- /dev/null
+++ b/src/cmd/vet/atomic.go
@@ -0,0 +1,59 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// checkAtomicAssignment walks the assignment statement checking for common
+// mistaken usage of atomic package, such as: x = atomic.AddUint64(&x, 1)
+func (f *File) checkAtomicAssignment(n *ast.AssignStmt) {
+	if !vet("atomic") {
+		return
+	}
+
+	if len(n.Lhs) != len(n.Rhs) {
+		return
+	}
+
+	for i, right := range n.Rhs {
+		call, ok := right.(*ast.CallExpr)
+		if !ok {
+			continue
+		}
+		sel, ok := call.Fun.(*ast.SelectorExpr)
+		if !ok {
+			continue
+		}
+		pkg, ok := sel.X.(*ast.Ident)
+		if !ok || pkg.Name != "atomic" {
+			continue
+		}
+
+		switch sel.Sel.Name {
+		case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr":
+			f.checkAtomicAddAssignment(n.Lhs[i], call)
+		}
+	}
+}
+
+// checkAtomicAddAssignment walks the atomic.Add* method calls checking for assigning the return value
+// to the same variable being used in the operation
+func (f *File) checkAtomicAddAssignment(left ast.Expr, call *ast.CallExpr) {
+	arg := call.Args[0]
+	broken := false
+
+	if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
+		broken = f.gofmt(left) == f.gofmt(uarg.X)
+	} else if star, ok := left.(*ast.StarExpr); ok {
+		broken = f.gofmt(star.X) == f.gofmt(arg)
+	}
+
+	if broken {
+		f.Warn(left.Pos(), "direct assignment to atomic value")
+	}
+}