LLVM Tutorial#6: Compilation Trouble

I am learning LLVM. In this series I am planning to walk through the introductory tutorial called Kaleidoscope at https://llvm.org/docs/tutorial/MyFirstLanguageFrontend/. In the last episode we implemented operator precedence. In this one, we attempt to finish writing the parser but ran into some problems compiling the program.

Transcript

The following transcript was automatically generated by an algorithm.

00:03 : all right we're live this is Toby and
00:06 : we're continuing this series where we we
00:10 : walk through the LLVM my first language
00:16 : front-end tutorial we're in the later
00:21 : part of Chapter two hopefully this is
00:25 : gonna be the episode that finishes
00:27 : chapter two chapter two has been a
00:29 : thinkthey chapter so in the last episode
00:34 : we finished although we haven't tested
00:36 : the code but we finished writing the
00:39 : code to parse binary operations and we
00:43 : did it in a way that hand those operator
00:45 : presidents and operator precedence is
00:50 : done using this technique which I
00:53 : believe is called the shunting yard
00:54 : algorithm where we assign a number to
00:58 : represent the presidents of each
01:00 : operator and then there's this clever
01:03 : logic during the parsing that makes use
01:07 : of that information to make the tree
01:12 : shift correctly to represent the correct
01:15 : presidents this time we're gonna do the
01:19 : section called parse the rest and let's
01:23 : just start by copying the example code
01:26 : line by line this one is gonna first
01:29 : prototype and what they mean by
01:32 : prototype in in their language it is not
01:36 : like a JavaScript prototype but is the
01:38 : prototype of a function which means the
01:40 : function signature so we're going to
01:42 : parse the function signature is what
01:45 : that means which which I think it looks
01:48 : like these are the parameter lists
02:02 : yeah you know this this is the function
02:06 : name and this this whole thing that's
02:09 : what we're parsing there's gonna be as
02:12 : identifiers token there's gonna be a
02:15 : left paren as a token there's gonna be
02:18 : another identifier token or for each of
02:21 : the parameter things in the parameter
02:22 : list it's gonna be a identifier token
02:24 : the comma is gonna be its own token this
02:28 : is gonna be an identifier and this is
02:31 : going to be a closing parenthesis
02:46 : and this function is going to return a
02:48 : unique pointer to a proto ast okay so is
02:57 : saying if current token is not a toque
03:03 : identifier we wear like throwing an
03:06 : error basically not use throwing of
03:10 : errors so this is the place where it
03:18 : actually uses the log error P function
03:22 : [Music]
03:24 : I'm still not sure why that's needed
03:27 : honestly so it can return the same type
03:35 : that's a waste that's it I don't like
03:38 : this way of doing it but that I won't
03:42 : complain too much
03:43 : I mean whoever wrote this tutorial thank
03:47 : you so much I think I would have a much
03:51 : harder time learning LLVM so I will try
03:55 : my best not to criticize okay so
04:02 : basically expecting the first token to
04:06 : be an identifier it is not we're
04:08 : throwing in there or we're airing out
04:12 : and then and because we are verified
04:17 : that the current token is an identifier
04:20 : we expect the name of the identifier to
04:23 : be in identifier string we're gonna
04:25 : stick it in this function name variable
04:28 : and this get next token eats D
04:32 : identifier okay and now we're gonna
04:39 : we're expecting after eating the
04:43 : identifier token that the next token
04:46 : after that is going to be an open paren
04:48 : so I'll just copy this bit so if it's
04:54 : not an open paren again
04:56 : airing out right away and now we're
04:58 : gonna read the list of argument names
05:00 : I'm gonna type this out and then explain
05:02 : it line by line first we're gonna
05:07 : instantiate a vector of strings which
05:12 : are gonna be the argument names and then
05:16 : we're gonna do a while loop saying while
05:24 : let me see
05:27 : and so this is not comma delimited
05:30 : actually interesting it's not comma
05:36 : delimited that means my picture is like
05:40 : upar open print and no comma and they
05:46 : should look like that that's fine
05:49 : so I'll just follow what it does so I'll
05:52 : get next token yes identifier then we're
05:59 : gonna push push this token that
06:04 : identifier string to the back of this
06:06 : vector
06:11 : if current token is not a closing trend
06:17 : than the Derby problems okay because
06:21 : after the archer this argument lists
06:25 : we're expecting a closing print oh this
06:28 : should be our names and then but but if
06:34 : it is then we're going to consume that
06:36 : token and if everything is successful
06:42 : we're gonna return a neat pointer using
06:48 : make unique it's gonna be a unique
06:52 : pointer to a proto ast with the fun name
06:58 : the name and we're gonna need to use
07:01 : standard and move to move the art names
07:05 : I think okay interestingly it's it's not
07:19 : a unique pointer here not sure why but
07:24 : it is a unique pointers here okay so
07:27 : that parses the prototype of the
07:29 : function and now let's parse the
07:32 : definition I believe of a function
07:51 : so we're assuming that the current token
07:54 : is the DEF token so we're eating the DEF
07:57 : token
08:10 : if we did not successfully parse a
08:14 : prototype of the function we're gonna
08:16 : return the null pointer to signal that
08:18 : stuff failed
08:20 : now we're gonna I'm gonna do this
08:24 : because that's my style we're gonna
08:28 : parse an expression next and if that
08:35 : worked
08:38 : I'm gonna I think the different probably
08:42 : is gonna be the body of the function I
08:44 : believe again we're gonna use mix unique
08:50 : to new up so to speak a new function ast
08:58 : will put the proto in there and also the
09:04 : expression in there as the body of the
09:07 : function I would have called that body
09:12 : but okay whoops thing I just reverted a
09:21 : page okay okay so that this part is a
09:32 : function definition and now we're gonna
09:36 : write the code to parse an extern
09:39 : externus like there's a function that's
09:43 : just defined externally I think and then
09:46 : you're just gonna write like like
09:51 : external bar something like this and
09:57 : you're saying now somebody defined the
09:59 : fubar function not me
10:01 : but I know someone did so I want to call
10:05 : this function just let me call the
10:07 : function
10:18 : okay it already assumes that the extern
10:23 : token is the current token again in the
10:28 : same style and it's gonna oh I see this
10:32 : because this is gonna be a function food
10:35 : of that pick so it will look actually
10:37 : more like external ubar and so yeah okay
10:44 : the parse the top level expression and I
10:49 : think that's the last parse function we
10:52 : have to write
11:02 : okay dude that in two separate lines as
11:09 : I you don't have to do you get to the
11:14 : tutorial code as you want okay so this
11:20 : is saying what is a top-level expression
11:24 : I misspelled unique pointer pointer is
11:27 : spelled PTR obviously parse no space
11:34 : tableau expression so what is a
11:36 : top-level expression well we're just
11:38 : gonna pave an expression oh I see we're
11:46 : gonna wrap it inside a top level
11:48 : function like there's an implicit
11:50 : Poplarville function that's unnamed Wow
11:55 : and an empty vector for its arguments
12:01 : alright I didn't see that coming but
12:04 : that's cool
12:20 : do you need to move it no
12:26 : all right like that yeah and then we're
12:32 : gonna make another unique
12:45 : and standard move II and then I guess if
12:54 : that didn't work we're returning a null
12:58 : pointer all right now we're finally
13:00 : ready to test this code that's what the
13:03 : driver is about so let me write it out
13:09 : so this is like while true basically
13:12 : well true oh this is a prompt this is a
13:17 : girl repple repple so you can type in
13:23 : the code as you go I guess if you get a
13:29 : enough file it just returns out of this
13:34 : main loop function Oh semicolons will Oh
13:42 : get ignored what semicolons get ignored
13:50 : if it's a death then we're gonna handle
13:53 : definition if it said what does handle
13:58 : mean did you mean parse handled
14:04 : top-level expression
14:19 : where are these handle bla bla bla
14:22 : functions - do you even have these
14:25 : functions oh I see I see okay these
14:41 : handle definition why does he have these
14:44 : functions now as far as the definition
14:51 : and it'll just say I parse the
14:54 : definition but if it didn't work
14:57 : skip the token forever recovery okay
15:00 : fine
15:01 : hello I will copy this code and then
15:07 : okay now copy this code that does this
15:11 : this is like a Red Bull and then I will
15:16 : I'm not gonna do this president's
15:19 : diction or anything because I decided to
15:22 : do it using switch statements I think
15:36 : run the interpreter loops okay
15:39 : let's cross our fingers and hope this
15:41 : works
15:43 : I guess for now we don't actually get to
15:47 : see the ast structure that we generated
15:52 : oh it's gonna say is tell us that it
15:56 : successfully parse something that's this
15:59 : compile this code which I had a line to
16:05 : compile it previously I will reuse it so
16:08 : GCC my legacy see - oh my land I've been
16:14 : did not work in the program that's fixed
16:23 : six errors
16:27 : okay another colon here o space is
16:43 : required between consecutive right angle
16:47 : brackets Oh seriously
16:51 : so line 114 like I need space between
17:00 : those things oh that is true so now it's
17:13 : complaining about that in here okay all
17:18 : right let's go to the next one 150 220
17:27 : errors concern warnings
17:30 : okay when I use less to see the top of
17:34 : this error list might need to do like
17:50 : type number two
17:55 : [Music]
18:10 : make unique November called make unique
18:16 : and namespace standard probably I need
18:20 : to oh I need memory that's what it is
18:22 : that's what I heard and to include
18:25 : memory and order they used the unique
18:30 : pointer thing the smart pointers is a
18:34 : memory memory library still did not work
18:42 : not sure why there's still a space
18:48 : needed and also used value let's go to
19:10 : the top of these errors return null
19:13 : pointer 154 mmm
19:21 : I don't you want me to return a no-no
19:25 : variable constructor returning object of
19:29 : type a unique pointer of X / KS t so
19:42 : this log error function let me see
19:53 : he returns a null planner and and it's
19:57 : complaining to me about that
20:00 : it says no viable constructor returning
20:03 : object of type standard unique pointer
20:11 : of expert is T candidate constructor not
20:21 : viable expects an L value for a first
20:26 : argument so I think it's saying that
20:32 : it's not allowed to not allowed to
20:37 : return a null pointer isn't it saying
20:40 : that I'm just gonna make this be a void
20:45 : method and I'm not even gonna bother
20:48 : having this look error P I think I think
20:53 : we just use this one law error function
20:57 : and if we need to return something out
21:02 : use a separate statement to return the
21:05 : null pointer
21:18 : not sure whether my weather like why I
21:27 : am deviating from the tutorial I didn't
21:37 : have a block to this I should have done
21:41 : that
21:42 : oh I'm not even gonna have the air fog
21:47 : energy function anymore
21:49 : there's always gonna use the error
21:53 : function I think that's all there okay
22:02 : try again
22:05 : six warnings on 20 air we still have 20
22:09 : years jeez auto-type specifier is a C++
22:14 : 11 extension yes
22:18 : give that to me please I want to see
22:21 : fuzzy learn an extension please so I
22:24 : think that means I just have to in my
22:27 : command I stick this in there right no
22:34 : all right I've done this before you know
22:40 : this is pretty easy to do but I just
22:43 : need to google it
22:48 : how do you do this oh you do that
22:51 : standard equals C++ 11 this is for a
22:55 : claim I think I am actually using clang
23:04 : I think I'm already using clang but I
23:09 : don't know you might not be for warnings
23:13 : and 19 errors this time all right okay
23:18 : now we have no member named Mickey
23:24 : unique 157 if it's not cosmic unique
23:34 : then what is it called
23:43 : it is in the memory module and I didn't
23:49 : include the memory module his standard
24:01 : make unique standard make unique I
24:15 : rolled it like that every single time
24:23 : number expert ast use of undeclared
24:37 : identifier parse I might need to forward
24:46 : declare that let me try that now well I
24:55 : can copy the code from the tutorial I
24:59 : kind of like figuring it for myself
25:03 : figuring out for myself because I feel
25:09 : like then I can learn a lot more about
25:12 : the language that way
25:14 : however we could use the source code as
25:19 : a kind of a quick test
25:24 : so I'm gonna crap this first Oh
25:38 : this uses the LLVM libraries does it
25:43 : actually use the hell LP i erase he uses
25:46 : some STL extra really we may have a
25:59 : compiler
26:25 : only two errors generated now use of
26:30 : undeclared identifier parse been up
26:34 : right hand side wow that got that many
26:39 : things 248 so you're saying this is I
26:47 : need to forward declare this so in C and
26:51 : C++ if you wanna use a function that is
26:55 : has not been defined yet you have to
26:58 : forward declare the function like
27:01 : declare the function signature of the
27:06 : function before whereas in JavaScript
27:10 : there's not needed because of hoisting
27:12 : but not so in C and C++ in one error
27:18 : generated now not saying oh sorry that's
27:25 : interesting this I'm using clang but I
27:30 : think G plus plus is the same thing yeah
27:33 : yeah okay so this error is something
27:38 : about it's a call to implicitly deleted
27:43 : copy constructor of this unique pointer
27:48 : in algorithm
27:54 : in this push back here 194 I got this
28:05 : arc which is a unique pointer to an
28:10 : expression est we're using pushback to
28:15 : push it to this arch list and implicitly
28:19 : delete copy constructor is implicitly
28:22 : deleted because unique pointer of an
28:28 : expression est has a unique what
28:47 : I don't really understand what is saying
28:51 : to me mmm
28:56 : I guess I could look at their code
29:18 : okay and see if it works there
29:30 : I'm just
29:41 : [Music]
29:45 : disable API brick trucks undefined
29:55 : symbol linker command failed with exit
30:03 : code one being disabled he bi break
30:11 : checks
30:30 : where is my LOL game config that's there
30:36 : there's where I put it
30:38 : by the way before I started this I
30:41 : downloaded the pre-built version of LLVM
30:45 : from this page and I went and got the
30:51 : newest one which was version 10 came in
30:57 : March of this year and got the lowest
31:00 : ten I extracted it put it in LLVM inside
31:06 : my home directory and inside of it
31:09 : there's this bin directory I've never
31:14 : seen this before so I guess the best I
31:18 : can do is Google for
31:28 : I do find something related to this
31:30 : kaleidoscope tutorial you need to