vpaths matching doesn't use anchors and therefore ends up matching .clang-format with *.c or .hgignore with *.h

[assarbad]

I noticed this because .hgignore always ended up in the ["Header Files/*"] = { "*.hpp", "*.h", }, vpaths-mapping, despite there being another mapping with which I attempted to map .hgignore without any wildcard characters. The same evidently happens/happened for .clang-format.

The path.wilcards() function returns a match string that isn't anchored to the beginning and end of the string respectively, so returning matches when it would not be expected.

I think the appropriate way would be (or rather have been) to have path.wildcards() return patterns anchored between ^ and $, i.e. the beginning and end of a string respectively. But in this particular case it's rather finicky to work around this from the outside.

The issue with that seems to be that -- for obvious reasons -- the name path.wildcards is already bound by the time I try to manipulate it.

Essentially I have replace this single line by something along the lines of (not knowing, however, how much else this may influence or how many existing premake4.lua files it'd break):

                        local wildcards = "^" .. path.wildcards(pattern) .. "$"
                        local i = abspath:find(wildcards)

... to get my proverbial foot in the door. Still, only thanks to the way Premake4 was designed, it's possible without having to patch the C part of it.

This does not happen when replacement (the key in the vpaths table) is an empty string, btw.

The workaround

Somewhere in your premake4.lua place this code:

do
    local orig_getvpath = premake.project.getvpath
    premake.project.getvpath = function(prj, abspath)
        for replacement, patterns in pairs(prj.vpaths or {}) do
            for _, pattern in ipairs(patterns) do
                if abspath == pattern then
                    local stem, _ = replacement:gsub("%*", "")
                    return path.join(stem, abspath)
                end
            end
        end
        return orig_getvpath(prj, abspath)
    end
end

What it does is to replace premake.project.getvpath() with our own code, retaining a "function pointer" to the original function.

Then it goes through all replacements and respective patterns, looking for exact matches between patterns and path -- which should reasonably only happen whenever the pattern (and path) contain no wildcard characters anyway -- and if that was found uses a stripped down version of the logic in the original getvpath() and returns its result at the first match. This is exactly the behavior I would have expected when there are no wildcard characters in the pattern, but which wasn't the case due to using string.find without anchors.

---

FYI: I don't expect anyone but myself to fix/address this. However, perhaps it helps someone else who still uses Premake4 or raises awareness on that issue for Premake5 (I don't know how related the code bases truly are).

---

Here's one failed attempt:

do
    if premake.project.getvpath then
        local orig_getvpath = premake.project.getvpath
        premake.project.getvpath = function(prj, abspath)
            local orig_wildcards = path.wildcards
            -- just for a single call, fix up the wildcards() function
            path.wildcards = function(pattern)
                return "^" .. orig_wildcards(pattern) .. ""
            end
            local retval = orig_getvpath(prj, abspath)
            path.wildcards = orig_wildcards -- reset back to the original value
            return retval
        end
    end
end

This method also fails (filteridgroup and getfilegroup respectively use the premake.project.eachfile function, which I hoped to influence this way):

do
    local orig_wildcards = path.wildcards
    local orig_filteridgroup = premake.vstudio.vc2010.filteridgroup
    local orig_getfilegroup = premake.vstudio.vc2010.getfilegroup
    local replacement_wildcards = function(pattern)
        return "^" .. orig_wildcards(pattern) .. ""
    end
    premake.vstudio.vc2010.filteridgroup = function(prj)
        path.wildcards = replacement_wildcards -- just for a single call, fix up the wildcards() function
        local retval = orig_filteridgroup(prj)
        path.wildcards = orig_wildcards -- reset back to the original value
        return retval
    end
    premake.vstudio.vc2010.getfilegroup = function(prj, group)
        path.wildcards = replacement_wildcards -- just for a single call, fix up the wildcards() function
        local retval = orig_getfilegroup(prj, group)
        path.wildcards = orig_wildcards -- reset back to the original value
        return retval
    end
end