x/tools/cmd/cover: for increment statement is not covered #10467

dvyukov · 2015-04-15T15:36:15Z

cover instruments the following program:

func foo() {
    type Node struct {
        next *Node
        v int
    }
    for p := new(Node); p != nil; p = p.next {
        println("here")
        if p.v == 0 {
            break
        }
    }
}

as:

func foo() {
    GoCover.Count[0] = 1
    type Node struct {
        next    *Node
        v   int
    }
    for p := new(Node); p != nil; p = p.next {
        GoCover.Count[1] = 1
        println("here")
        if p.v == 0 {
            GoCover.Count[2] = 1
            break
        }
    }
}

As the result it is not possible to understand whether 'p = p.next' statement covered or not.

One way to fix it would be to emit coverage instrumentation before continue statements and at loop end. For example, in this case the following would do:

    for p := new(Node); p != nil; p = p.next {
        GoCover.Count[1] = 1
        println("here")
        if p.v == 0 {
            GoCover.Count[2] = 1
            break
        }
        GoCover.Count[3] = 1
    }

robpike · 2015-04-15T17:11:32Z

A known and minor weakness of the source-oriented design. I do not intend to fix this.

dvyukov assigned robpike Apr 15, 2015

dvyukov added this to the Go1.5 milestone Apr 15, 2015

dvyukov changed the title ~~cmd/cover: for increment statement is not covered~~ x/tools/cmd/cover: for increment statement is not covered Apr 15, 2015

robpike closed this as completed Apr 15, 2015

golang locked and limited conversation to collaborators Jun 25, 2016

gopherbot added the FrozenDueToAge label Jun 25, 2016

rsc unassigned robpike Jun 23, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

x/tools/cmd/cover: for increment statement is not covered #10467

x/tools/cmd/cover: for increment statement is not covered #10467

dvyukov commented Apr 15, 2015

robpike commented Apr 15, 2015

x/tools/cmd/cover: for increment statement is not covered #10467

x/tools/cmd/cover: for increment statement is not covered #10467

Comments

dvyukov commented Apr 15, 2015

robpike commented Apr 15, 2015