Crystal tool expand example?

rogerdpack · October 15, 2021, 2:18am

Could somebody help me find an example of “crystal tool expand” where it works? Mine always says “no expansion found” …

What I’m kind of wishing for is a way to see “a file after the macros are fully expanded”…

In case useful in cases like these:

github.com/crystal-lang/crystal

Improve backtraces

opened 06:50PM - 09 Jun 16 UTC

mperham

kind:feature topic:compiler

While porting some Ruby code to Crystal, I ran some specs and found that the err…or backtraces were missing huge chunks of code frames. It was very painful to debug the issues due to incomplete backtraces, often missing line numbers. Here's an example: ``` cast to Int failed [4525793250] *CallStack::unwind:Array(Pointer(Void)) +82 [4525793153] *CallStack#initialize<CallStack>:Array(Pointer(Void)) +17 [4525793112] *CallStack::new:CallStack +40 [4526322281] *Exception@Exception#initialize<TypeCastError, String>:CallStack +41 [4526322205] *TypeCastError#initialize<TypeCastError, String>:CallStack +29 [4526322148] *TypeCastError::new<String>:TypeCastError +100 [4525582152] ~proc(HTTP::Server::Context -> String)@./src/sidekiq/web.cr:88 +2072 [4525566338] ~proc(HTTP::Server::Context -> String)@./libs/kemal/kemal/route.cr:10 +66 [4526712301] *Kemal::RouteHandler#process_request<Kemal::RouteHandler, HTTP::Server::Context>:HTTP::Server::Context +125 [4526712157] *Kemal::RouteHandler#call<Kemal::RouteHandler, HTTP::Server::Context>:HTTP::Server::Context +93 [4525709936] *get<String, Nil, Nil>:(HTTP::Server::Response::Output | IO::FileDescriptor+ | Int32 | Nil) +192 [4526809829] */Users/mike/src/sidekiq.cr/spec/web_spec.cr#get<String>:(HTTP::Server::Response::Output | IO::FileDescriptor+ | Int32 | Nil) +21 [4525728014] ~proc( -> Void)@./spec/web_spec.cr:286 +2718 [4525503099] *it<String, String, Int32, &( -> Void)>:(Array(Spec::Result) | Bool | Nil) +427 [4525704007] ~proc( -> Void)@./spec/web_spec.cr:4 +1831 [4525994230] *Spec::RootContext::describe<String, String, Int32, &( -> Void)>:Spec::Context+ +310 [4525501977] *describe<String, String, Int32, &( -> Void)>:Spec::Context+ +9 [4525431833] __crystal_main +31705 [4525483016] main +40 ``` Note the top element in my code: sidekiq/web.cr:88: ``` ruby get "/busy" do |x| ecr("busy") end ``` Great. ECR pushes the entire template into the code. None of it is visible in backtrace. So I throw in some `raise "boom"` in the template to bisect down to this line: ``` ruby <% x.processes.each do |process| %> ``` This calls Sidekiq::ProcessSet#each: ``` ruby def each Sidekiq.redis do |conn| prcs = conn.smembers("processes") procs = [] of String prcs.each { |x| procs << x.as(String) } procs.sort! # We're making a tradeoff here between consuming more memory instead of # making more roundtrips to Redis, but if you have hundreds or thousands of workers, # you'll be happier this way results = conn.pipelined do |ppp| procs.each do |key| ppp.hmget(key, "info", "busy", "beat", "quiet") end end.as(Array(Redis::RedisValue)) results.each do |x| packet = x.as(Array(Redis::RedisValue)) info = packet[0].as(String) busy = packet[1].as(Int).to_i64 # <========= ACTUAL BUG beat = packet[2].as(String).to_f64 quiet = packet[3]?.to_s == "true" hash = JSON.parse(info).as_h hash["busy"] = busy hash["beat"] = beat hash["quiet"] = quiet yield Process.new(hash) end end nil end ``` This is one example of how debugging is painful today due to huge gaps in error backtraces. The equivalent Ruby backtrace would have 4-6 frames between these two lines and make for a 20 second bugfix instead of a 20 minute bughunt. ``` [4526322148] *TypeCastError::new<String>:TypeCastError +100 [4525582152] ~proc(HTTP::Server::Context -> String)@./src/sidekiq/web.cr:88 +2072 ``` Are there any easy wins to improve the situation?

Thanks!

rogerdpack · October 15, 2021, 2:36am

OK found one Is there a way to see what a Crystal macro expands to? - Stack Overflow

Still hope to someday be able to get full backtraces and “fully expanded files” for debugging

Also contains a fix’ish workaround for the “upgrade to 1.x Error: undefined method ‘mapping’ for JSON:Module” failure message.

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