fix timeout in ZCS receiveMessage (#1264)

src/ZigCompileServer.zig

@@ -32,32 +32,27 @@ pub fn receiveMessage(client: *Client) !InMessage.Header {
     const Header = InMessage.Header;
     const fifo = client.pooler.fifo(.in);
 
-    while (try client.pooler.poll()) {
+    var first_run = true;
+    var header: ?Header = null;
+    while (first_run or try client.pooler.poll()) {
+        first_run = false;
+
+        if (header == null) {
+            if (fifo.readableLength() < @sizeOf(Header)) continue;
             const buf = fifo.readableSlice(0);
-        assert(fifo.readableLength() == buf.len);
-        if (buf.len >= @sizeOf(Header)) {
-            // workaround for https://github.com/ziglang/zig/issues/14904
             const bytes_len = bswap_and_workaround_u32(buf[4..][0..4]);
             const tag = bswap_and_workaround_tag(buf[0..][0..4]);
-
-            if (buf.len - @sizeOf(Header) >= bytes_len) {
-                fifo.discard(@sizeOf(Header));
-                return .{
+            header = Header{
                 .tag = tag,
                 .bytes_len = bytes_len,
             };
-            } else {
-                const needed = bytes_len - (buf.len - @sizeOf(Header));
-                const write_buffer = try fifo.writableWithSize(needed);
-                const amt = try client.in.readAll(write_buffer);
-                fifo.update(amt);
-                continue;
-            }
+            fifo.discard(@sizeOf(Header));
         }
 
-        const write_buffer = try fifo.writableWithSize(256);
-        const amt = try client.in.read(write_buffer);
-        fifo.update(amt);
+        if (header) |h| {
+            if (fifo.readableLength() < h.bytes_len) continue;
+            return h;
+        }
     }
     return error.Timeout;
 }

src/translate_c.zig

@@ -236,12 +236,10 @@ pub fn translate(
                 const body_size = @sizeOf(std.zig.Server.Message.EmitBinPath);
                 if (header.bytes_len <= body_size) return error.InvalidResponse;
 
-                const trailing_size = header.bytes_len - body_size;
-
                 _ = try zcs.receiveEmitBinPath();
 
-                const result_path = try zcs.receiveBytes(allocator, trailing_size);
-                defer allocator.free(result_path);
+                const trailing_size = header.bytes_len - body_size;
+                const result_path = zcs.pooler.fifo(.in).readableSliceOfLen(trailing_size);
 
                 return Result{ .success = try URI.fromPath(allocator, std.mem.sliceTo(result_path, '\n')) };
             },

tests/language_features/cimport.zig

@@ -9,9 +9,6 @@ const translate_c = zls.translate_c;
 const allocator: std.mem.Allocator = std.testing.allocator;
 
 test "zig compile server - translate c" {
-    // FIXME: Disabled due to https://github.com/zigtools/zls/issues/1252
-    if (@import("builtin").os.tag == .windows) return error.SkipZigTest;
-
     var result1 = try testTranslate(
         \\void foo(int);
         \\void bar(float*);