feat(linker): use relative targets for symlinks

Closes #1156.

lua/mason-core/installer/linker.lua

@@ -73,7 +73,7 @@ end
 ---@async
 ---@param context InstallContext
 ---@param link_context LinkContext
----@param link_fn async fun(new_abs_path: string, target_abs_path: string): Result
+---@param link_fn async fun(new_abs_path: string, target_abs_path: string, target_rel_path: string): Result
 local function link(context, link_context, link_fn)
     log.trace("Linking", context.package, link_context.type, context.links[link_context.type])
     return Result.try(function(try)
@@ -83,6 +83,7 @@ local function link(context, link_context, link_fn)
             end
             local new_abs_path = link_context.prefix(name, context.location)
             local target_abs_path = path.concat { context.package:get_install_path(), rel_path }
+            local target_rel_path = path.relative(new_abs_path, target_abs_path)
 
             do
                 -- 1. Ensure destination directory exists
@@ -109,7 +110,7 @@ local function link(context, link_context, link_fn)
             end
 
             -- 3. Execute link.
-            try(link_fn(new_abs_path, target_abs_path))
+            try(link_fn(new_abs_path, target_abs_path, target_rel_path))
             context.receipt:with_link(link_context.type, name, rel_path)
         end
     end)
@@ -118,8 +119,8 @@ end
 ---@param context InstallContext
 ---@param link_context LinkContext
 local function symlink(context, link_context)
-    return link(context, link_context, function(new_abs_path, target_abs_path)
-        return Result.pcall(fs.async.symlink, target_abs_path, new_abs_path)
+    return link(context, link_context, function(new_abs_path, _, target_rel_path)
+        return Result.pcall(fs.async.symlink, target_rel_path, new_abs_path)
     end)
 end
 
@@ -133,7 +134,8 @@ end
 
 ---@param context InstallContext
 local function win_bin_wrapper(context)
-    return link(context, LinkContext.BIN, function(new_abs_path, target_abs_path)
+    return link(context, LinkContext.BIN, function(new_abs_path, __, target_rel_path)
+        local windows_target_rel_path = target_rel_path:gsub("/", "\\")
         return Result.pcall(
             fs.async.write_file,
             new_abs_path,
@@ -147,8 +149,8 @@ local function win_bin_wrapper(context)
                 SETLOCAL
                 CALL :find_dp0
 
-                endLocal & goto #_undefined_# 2>NUL || title %%COMSPEC%% & "%s" %%*
-            ]]):format(target_abs_path))
+                endLocal & goto #_undefined_# 2>NUL || title %%COMSPEC%% & "%%dp0%%\%s" %%*
+            ]]):format(windows_target_rel_path))
         )
     end)
 end

lua/mason-core/path.lua

@@ -56,7 +56,7 @@ function M.relative(from, to)
 
     local common_parent, distance = find_closest_common_parent(from_normalized, to_normalized)
     local relative_path_component = distance == 0 and "." or (".."):rep(distance, "/")
-    return vim.fs.joinpath(relative_path_component, to_normalized:sub(#common_parent + 1))
+    return M.concat { relative_path_component, to_normalized:sub(#common_parent + 1) }
 end
 
 return M

tests/mason-core/installer/linker_spec.lua

@@ -14,7 +14,7 @@ EXIT /b
 SETLOCAL
 CALL :find_dp0
 
-endLocal & goto #_undefined_# 2>NUL || title %%COMSPEC%% & "%s" %%*]]
+endLocal & goto #_undefined_# 2>NUL || title %%COMSPEC%% & "%%dp0%%\%s" %%*]]
 
 describe("linker", function()
     local snapshot
@@ -63,13 +63,10 @@ describe("linker", function()
         assert.spy(fs.async.symlink).was_called(2)
         assert
             .spy(fs.async.symlink)
-            .was_called_with(path.concat { dummy:get_install_path(), "another-executable" }, ctx.location:bin "another-executable")
+            .was_called_with("../packages/dummy/another-executable", ctx.location:bin "another-executable")
         assert
             .spy(fs.async.symlink)
-            .was_called_with(
-                path.concat { dummy:get_install_path(), "nested", "path", "my-executable" },
-                ctx.location:bin "my-executable"
-            )
+            .was_called_with("../packages/dummy/nested/path/my-executable", ctx.location:bin "my-executable")
     end)
 
     it("should write executable wrapper on Windows", function()
@@ -101,14 +98,15 @@ describe("linker", function()
 
         assert.spy(fs.async.symlink).was_called(0)
         assert.spy(fs.async.write_file).was_called(2)
-        assert.spy(fs.async.write_file).was_called_with(
-            ctx.location:bin "another-executable.cmd",
-            WIN_CMD_SCRIPT:format(path.concat { dummy:get_install_path(), "another-executable" })
-        )
-        assert.spy(fs.async.write_file).was_called_with(
-            ctx.location:bin "my-executable.cmd",
-            WIN_CMD_SCRIPT:format(path.concat { dummy:get_install_path(), "nested", "path", "my-executable" })
-        )
+        assert
+            .spy(fs.async.write_file)
+            .was_called_with(ctx.location:bin "another-executable.cmd", WIN_CMD_SCRIPT:format "..\\packages\\dummy\\another-executable")
+        assert
+            .spy(fs.async.write_file)
+            .was_called_with(
+                ctx.location:bin "my-executable.cmd",
+                WIN_CMD_SCRIPT:format "..\\packages\\dummy\\nested\\path\\my-executable"
+            )
     end)
 
     it("should symlink share files", function()
@@ -142,13 +140,10 @@ describe("linker", function()
 
         assert.spy(fs.async.write_file).was_called(0)
         assert.spy(fs.async.symlink).was_called(2)
+        assert.spy(fs.async.symlink).was_called_with("../packages/dummy/share-file", ctx.location:share "share-file")
         assert
             .spy(fs.async.symlink)
-            .was_called_with(path.concat { dummy:get_install_path(), "share-file" }, ctx.location:share "share-file")
-        assert.spy(fs.async.symlink).was_called_with(
-            path.concat { dummy:get_install_path(), "nested", "path", "to", "share-file" },
-            ctx.location:share "nested/path/share-file"
-        )
+            .was_called_with("../../../packages/dummy/nested/path/to/share-file", ctx.location:share "nested/path/share-file")
 
         assert.spy(fs.async.mkdirp).was_called(2)
         assert.spy(fs.async.mkdirp).was_called_with(ctx.location:share "nested/path")