resolve list of compilation units from build runner

Author: Techatrix

src/build_runner/build_runner.zig

@@ -1031,6 +1031,7 @@ fn extractBuildInformation(
             modules: *std.StringArrayHashMapUnmanaged(shared.BuildConfig.Module),
             module: *std.Build.Module,
             compile: ?*Step.Compile,
+            cwd: []const u8,
         ) !void {
             const root_source_file = module.root_source_file orelse return;
 
@@ -1084,8 +1085,6 @@ fn extractBuildInformation(
                 }
             }
 
-            const cwd = try std.process.getCwdAlloc(allocator);
-
             const root_source_file_path = try std.fs.path.resolve(allocator, &.{ cwd, root_source_file.getPath2(module.owner, null) });
 
             // All modules with the same root source file are merged. This limitation may be lifted in the future.
@@ -1190,11 +1189,12 @@ fn extractBuildInformation(
     // - modules that are reachable from the "install" step
     // - all other reachable modules
     var modules: std.StringArrayHashMapUnmanaged(BuildConfig.Module) = .empty;
+    const cwd = try std.process.getCwdAlloc(arena);
 
     for (b.modules.values()) |root_module| {
         const graph = root_module.getGraph();
         for (graph.modules) |module| {
-            try helper.processModule(arena, &modules, module, null);
+            try helper.processModule(arena, &modules, module, null, cwd);
         }
     }
 
@@ -1206,11 +1206,21 @@ fn extractBuildInformation(
             const compile = step.cast(Step.Compile) orelse continue;
             const graph = compile.root_module.getGraph();
             for (graph.modules) |module| {
-                try helper.processModule(arena, &modules, module, compile);
+                try helper.processModule(arena, &modules, module, compile, cwd);
             }
         }
     }
 
+    var compilations: std.ArrayList(BuildConfig.Compile) = .empty;
+    for (all_steps.keys()) |step| {
+        const compile = step.cast(Step.Compile) orelse continue;
+        const root_source_file = compile.root_module.root_source_file orelse continue;
+        const root_source_file_path = try std.fs.path.resolve(arena, &.{ cwd, root_source_file.getPath2(compile.root_module.owner, null) });
+        try compilations.append(arena, .{
+            .root_module = root_source_file_path,
+        });
+    }
+
     // Sample `@dependencies` structure:
     // pub const packages = struct {
     //     pub const @"1220363c7e27b2d3f39de6ff6e90f9537a0634199860fea237a55ddb1e1717f5d6a5" = struct {
@@ -1255,6 +1265,7 @@ fn extractBuildInformation(
         BuildConfig{
             .dependencies = .{ .map = root_dependencies },
             .modules = .{ .map = modules },
+            .compilations = compilations.items,
             .top_level_steps = b.top_level_steps.keys(),
             .available_options = .{ .map = available_options },
         },

src/build_runner/shared.zig

@@ -9,6 +9,8 @@ pub const BuildConfig = struct {
     /// The key is the `root_source_file`.
     /// All modules with the same root source file are merged. This limitation may be lifted in the future.
     modules: std.json.ArrayHashMap(Module),
+    /// List of all compilations units.
+    compilations: []const Compile,
     /// The names of all top level steps.
     top_level_steps: []const []const u8,
     available_options: std.json.ArrayHashMap(AvailableOption),
@@ -19,6 +21,13 @@ pub const BuildConfig = struct {
         include_dirs: []const []const u8,
     };
 
+    pub const Compile = struct {
+        /// Key in `BuildConfig.modules`.
+        root_module: []const u8,
+
+        // may contain additional information in the future like `target` or `link_libc`.
+    };
+
     /// Equivalent to `std.Build.AvailableOption` which is not accessible because it non-pub.
     pub const AvailableOption = @FieldType(@FieldType(std.Build, "available_options_map").KV, "value");
 };

tests/build_runner_cases/add_module.json

@@ -7,6 +7,7 @@
       "include_dirs": []
     }
   },
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/define_c_macro.json

@@ -9,6 +9,7 @@
       "include_dirs": []
     }
   },
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/empty.json

@@ -1,6 +1,7 @@
 {
   "dependencies": {},
   "modules": {},
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/module_root_source_file_collision.json

@@ -26,6 +26,11 @@
       "include_dirs": []
     }
   },
+  "compilations": [
+    {
+      "root_module": "main.zig"
+    }
+  ],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/module_self_import.json

@@ -9,6 +9,7 @@
       "include_dirs": []
     }
   },
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/multiple_module_import_names.json

@@ -24,6 +24,7 @@
       "include_dirs": []
     }
   },
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_cases/public_module_with_generated_file.json

@@ -7,6 +7,7 @@
       "include_dirs": []
     }
   },
+  "compilations": [],
   "top_level_steps": [
     "install",
     "uninstall"

tests/build_runner_check.zig

@@ -52,6 +52,10 @@ pub fn main() !u8 {
             try mod.import_table.map.reIndex(arena);
         }
 
+        for (new.compilations) |*compile| {
+            @as(*[]const u8, @constCast(&compile.root_module)).* = try sanitizePath(arena, compile.root_module, cwd, local_cache_dir, global_cache_dir);
+        }
+
         break :sanitized try std.json.Stringify.valueAlloc(
             gpa,
             new,