build_runner: Require some paths to be given (#369)

We now require the following to ge given in the cli args:
- zig_exe
- build_root
- cache_root
- global_cache_root

This fixes the path for packages that use one or more from the above to place
their files.

src/DocumentStore.zig

@@ -52,8 +52,19 @@ build_files: std.ArrayListUnmanaged(*BuildFile),
 build_runner_path: []const u8,
 build_runner_cache_path: []const u8,
 std_uri: ?[]const u8,
+zig_cache_root: []const u8,
+zig_global_cache_root: []const u8,
 
-pub fn init(self: *DocumentStore, allocator: std.mem.Allocator, zig_exe_path: ?[]const u8, build_runner_path: []const u8, build_runner_cache_path: []const u8, zig_lib_path: ?[]const u8) !void {
+pub fn init(
+    self: *DocumentStore,
+    allocator: std.mem.Allocator,
+    zig_exe_path: ?[]const u8,
+    build_runner_path: []const u8,
+    build_runner_cache_path: []const u8,
+    zig_lib_path: ?[]const u8,
+    zig_cache_root: []const u8,
+    zig_global_cache_root: []const u8,
+) !void {
     self.allocator = allocator;
     self.handles = std.StringHashMap(*Handle).init(allocator);
     self.zig_exe_path = zig_exe_path;
@@ -61,6 +72,8 @@ pub fn init(self: *DocumentStore, allocator: std.mem.Allocator, zig_exe_path: ?[
     self.build_runner_path = build_runner_path;
     self.build_runner_cache_path = build_runner_cache_path;
     self.std_uri = try stdUriFromLibPath(allocator, zig_lib_path);
+    self.zig_cache_root = zig_cache_root;
+    self.zig_global_cache_root = zig_global_cache_root;
 }
 
 fn loadBuildAssociatedConfiguration(allocator: std.mem.Allocator, build_file: *BuildFile, build_file_path: []const u8) !void {
@@ -98,6 +111,8 @@ const LoadPackagesContext = struct {
     build_runner_cache_path: []const u8,
     zig_exe_path: []const u8,
     build_file_path: ?[]const u8 = null,
+    cache_root: []const u8,
+    global_cache_root: []const u8,
 };
 
 fn loadPackages(context: LoadPackagesContext) !void {
@@ -123,6 +138,11 @@ fn loadPackages(context: LoadPackagesContext) !void {
             "@build@",
             build_file_path,
             "--pkg-end",
+            "--",
+            zig_exe_path,
+            directory_path,
+            context.cache_root,
+            context.global_cache_root,
         },
     });
 
@@ -229,6 +249,8 @@ fn newDocument(self: *DocumentStore, uri: []const u8, text: [:0]u8) anyerror!*Ha
             .build_runner_cache_path = self.build_runner_cache_path,
             .zig_exe_path = self.zig_exe_path.?,
             .build_file_path = build_file_path,
+            .cache_root = self.zig_cache_root,
+            .global_cache_root = self.zig_global_cache_root,
         }) catch |err| {
             log.debug("Failed to load packages of build file {s} (error: {})", .{ build_file.uri, err });
         };
@@ -496,6 +518,8 @@ pub fn applySave(self: *DocumentStore, handle: *Handle) !void {
             .build_runner_path = self.build_runner_path,
             .build_runner_cache_path = self.build_runner_cache_path,
             .zig_exe_path = self.zig_exe_path.?,
+            .cache_root = self.zig_cache_root,
+            .global_cache_root = self.zig_global_cache_root,
         }) catch |err| {
             log.debug("Failed to load packages of build file {s} (error: {})", .{ build_file.uri, err });
         };

src/main.zig

@@ -1815,6 +1815,13 @@ pub fn main() anyerror!void {
         build_runner_path,
         build_runner_cache_path,
         config.zig_lib_path,
+        // TODO make this configurable
+        // We can't figure it out ourselves since we don't know what arguments
+        // the user will use to run "zig build"
+        "zig-cache",
+        // Since we don't compile anything and no packages should put their
+        // files there this path can be ignored
+        "ZLS_DONT_CARE",
     );
     defer document_store.deinit();
 

src/special/build_runner.zig

@@ -1,7 +1,9 @@
 const root = @import("@build@");
 const std = @import("std");
-const io = std.io;
 const fmt = std.fmt;
+const io = std.io;
+const log = std.log;
+const process = std.process;
 const Builder = std.build.Builder;
 const Pkg = std.build.Pkg;
 const InstallArtifactStep = std.build.InstallArtifactStep;
@@ -17,7 +19,37 @@ pub fn main() !void {
 
     const allocator = arena.allocator();
 
-    const builder = try Builder.create(allocator, "", "", "", "");
+    var args = try process.argsAlloc(allocator);
+    defer process.argsFree(allocator, args);
+
+    // skip my own exe name
+    var arg_idx: usize = 1;
+
+    const zig_exe = nextArg(args, &arg_idx) orelse {
+        log.warn("Expected first argument to be path to zig compiler\n", .{});
+        return error.InvalidArgs;
+    };
+    const build_root = nextArg(args, &arg_idx) orelse {
+        log.warn("Expected second argument to be build root directory path\n", .{});
+        return error.InvalidArgs;
+    };
+    const cache_root = nextArg(args, &arg_idx) orelse {
+        log.warn("Expected third argument to be cache root directory path\n", .{});
+        return error.InvalidArgs;
+    };
+    const global_cache_root = nextArg(args, &arg_idx) orelse {
+        log.warn("Expected third argument to be global cache root directory path\n", .{});
+        return error.InvalidArgs;
+    };
+
+    const builder = try Builder.create(
+        allocator,
+        zig_exe,
+        build_root,
+        cache_root,
+        global_cache_root,
+    );
+
     defer builder.destroy();
 
     builder.resolveInstallPrefix(null, Builder.DirList{});
@@ -71,3 +103,9 @@ fn runBuild(builder: *Builder) anyerror!void {
         else => @compileError("expected return type of build to be 'void' or '!void'"),
     }
 }
+
+fn nextArg(args: [][]const u8, idx: *usize) ?[]const u8 {
+    if (idx.* >= args.len) return null;
+    defer idx.* += 1;
+    return args[idx.*];
+}