add "build.fence" policy to block all targets build in depend chain

tests/projects/other/autogen_codedep/xmake.lua

@@ -24,12 +24,12 @@ target("autogen")
     set_arch(os.arch())
     add_files("src/autogen.cpp")
     set_languages("c++11")
+    set_policy("build.fence", true)
 
 target("test")
     set_kind("binary")
     add_deps("autogen")
     add_rules("autogen")
     add_files("src/main.cpp")
     add_files("src/*.in")
-    set_policy("build.across_targets_in_parallel", false)
 

xmake/actions/build/build.lua

@@ -207,22 +207,23 @@ function _add_batchjobs_for_target(batchjobs, rootjob, target)
 end
 
 -- add batch jobs for the given target and deps
-function _add_batchjobs_for_target_and_deps(batchjobs, rootjob, jobrefs, target)
+function _add_batchjobs_for_target_and_deps(batchjobs, rootjob, target, jobrefs, jobrefs_before)
     local targetjob_ref = jobrefs[target:name()]
     if targetjob_ref then
         batchjobs:add(targetjob_ref, rootjob)
     else
         local job_build_before, job_build, job_build_after = _add_batchjobs_for_target(batchjobs, rootjob, target)
         if job_build_before and job_build and job_build_after then
             jobrefs[target:name()] = job_build_after
+            jobrefs_before[target:name()] = job_build_before
             for _, depname in ipairs(target:get("deps")) do
                 local dep = project.target(depname)
                 local targetjob = job_build
                 -- @see https://github.com/xmake-io/xmake/discussions/2500
                 if dep:policy("build.across_targets_in_parallel") == false then
                     targetjob = job_build_before
                 end
-                _add_batchjobs_for_target_and_deps(batchjobs, targetjob, jobrefs, dep)
+                _add_batchjobs_for_target_and_deps(batchjobs, targetjob, dep, jobrefs, jobrefs_before)
             end
         end
     end
@@ -251,7 +252,7 @@ function get_batchjobs(targetnames, group_pattern)
     else
         local depset = hashset.new()
         local targets = {}
-        for _, target in pairs(project.targets()) do
+        for _, target in ipairs(project.ordertargets()) do
             if target:is_enabled() then
                 local group = target:get("group")
                 if (target:is_default() and not group_pattern) or option.get("all") or (group_pattern and group and group:match(group_pattern)) then
@@ -262,7 +263,7 @@ function get_batchjobs(targetnames, group_pattern)
                 end
             end
         end
-        for _, target in pairs(targets) do
+        for _, target in ipairs(targets) do
             if not depset:has(target:name()) then
                 table.insert(targets_root, target)
             end
@@ -274,10 +275,27 @@ function get_batchjobs(targetnames, group_pattern)
 
     -- generate batch jobs for default or all targets
     local jobrefs = {}
+    local jobrefs_before = {}
     local batchjobs = jobpool.new()
-    for _, target in pairs(targets_root) do
-        _add_batchjobs_for_target_and_deps(batchjobs, batchjobs:rootjob(), jobrefs, target)
+    for _, target in ipairs(targets_root) do
+        _add_batchjobs_for_target_and_deps(batchjobs, batchjobs:rootjob(), target, jobrefs, jobrefs_before)
     end
+
+    -- add fence jobs, @see https://github.com/xmake-io/xmake/issues/5003
+    for _, target in ipairs(project.ordertargets()) do
+        local target_job_before = jobrefs_before[target:name()]
+        if target_job_before then
+            for _, dep in ipairs(target:orderdeps()) do
+                if dep:policy("build.fence") then
+                    local fence_job = jobrefs[dep:name()]
+                    if fence_job then
+                        batchjobs:add(fence_job, target_job_before)
+                    end
+                end
+            end
+        end
+    end
+
     return batchjobs
 end
 
@@ -303,4 +321,3 @@ function main(targetnames, group_pattern)
         os.cd(curdir)
     end
 end
-

xmake/core/project/policy.lua

@@ -40,6 +40,8 @@ function policy.policies()
             ["check.auto_map_flags"]              = {description = "Enable map gcc flags to the current compiler and linker automatically.", default = true, type = "boolean"},
             -- We will check the compatibility of target and package licenses
             ["check.target_package_licenses"]     = {description = "Enable check the compatibility of target and package licenses.", default = true, type = "boolean"},
+            -- Provide a way to block all targets build that depends on self
+            ["build.fence"]                       = {description = "Block all targets build that depends on self.", default = false, type = "boolean"},
             -- We can compile the source files for each target in parallel
             ["build.across_targets_in_parallel"]  = {description = "Enable compile the source files for each target in parallel.", default = true, type = "boolean"},
             -- Merge archive intead of linking for all dependent targets