Auto merge of #66314 - GuillaumeGomez:move-error-codes, r=Centril

Move error codes

Works towards #66210.

r? @Centril

Oh btw, for the ones interested, I used this python script to get all error codes content sorted into one final file:

<details>

```python
from os import listdir
from os.path import isdir, isfile, join

def get_error_codes(error_codes, f_path):
    with open(f_path) as f:
        short_mode = False
        lines = f.read().split("\n")
        i = 0
        while i < len(lines):
            line = lines[i]
            if not short_mode and line.startswith("E0") and line.endswith(": r##\""):
                error = line
                error += "\n"
                i += 1
                while i < len(lines):
                    line = lines[i]
                    error += line
                    if line.endswith("\"##,"):
                        break
                    error += "\n"
                    i += 1
                error_codes["long"].append(error)
            elif line == ';':
                short_mode = True
            elif short_mode is True and len(line) > 0 and line != "}":
                error_codes["short"].append(line)
                while i + 1 < len(lines):
                    line = lines[i + 1].strip()
                    if not line.startswith("//"):
                        break
                    parts = line.split("//")
                    if len(parts) < 2:
                        break
                    if parts[1].strip().startswith("E0"):
                        break
                    error_codes["short"][-1] += "\n"
                    error_codes["short"][-1] += lines[i + 1]
                    i += 1
            i += 1

def loop_dirs(error_codes, cur_dir):
    for entry in listdir(cur_dir):
        f = join(cur_dir, entry)
        if isfile(f) and entry == "error_codes.rs":
            get_error_codes(error_codes, f)
        elif isdir(f) and not entry.startswith("librustc_error_codes"):
            loop_dirs(error_codes, f)

def get_error_code(err):
    x = err.split(",")
    if len(x) < 2:
        return err
    x = x[0]
    if x.strip().startswith("//"):
        x = x.split("//")[1].strip()
    return x.strip()

def write_into_file(error_codes, f_path):
    with open(f_path, "w") as f:
        f.write("// Error messages for EXXXX errors.  Each message should start and end with a\n")
        f.write("// new line, and be wrapped to 80 characters.  In vim you can `:set tw=80` and\n")
        f.write("// use `gq` to wrap paragraphs. Use `:set tw=0` to disable.\n\n")
        f.write("syntax::register_diagnostics! {\n\n")
        error_codes["long"].sort()
        for i in error_codes["long"]:
            f.write(i)
            f.write("\n\n")
        f.write(";\n")
        error_codes["short"] = sorted(error_codes["short"], key=lambda err: get_error_code(err))
        for i in error_codes["short"]:
            f.write(i)
            f.write("\n")
        f.write("}\n")

error_codes = {
    "long": [],
    "short": []
}
loop_dirs(error_codes, "src")
write_into_file(error_codes, "src/librustc_error_codes/src/error_codes.rs")
```
</details>

And to move the error codes into their own files:

<details>

```python
import os

try:
    os.mkdir("src/librustc_error_codes/error_codes")
except OSError:
    print("Seems like folder already exist, moving on!")
data = ''
with open("src/librustc_error_codes/error_codes.rs") as f:
    x = f.read().split('\n')
    i = 0
    short_part = False
    while i < len(x):
        line = x[i]
        if short_part is False and line.startswith('E0') and line.endswith(': r##"'):
            err_code = line.split(':')[0]
            i += 1
            content = ''
            while i < len(x):
                if x[i] == '"##,':
                    break
                content += x[i]
                content += '\n'
                i += 1
            f_path = "src/librustc_error_codes/error_codes/{}.md".format(err_code)
            with open(f_path, "w") as ff:
                ff.write(content)
            data += '{}: include_str!("./error_codes/{}.md"),'.format(err_code, err_code)
        elif short_part is False and line == ';':
            short_part is True
            data += ';\n'
        else:
            data += line
            data += '\n'
        i += 1
with open("src/librustc_error_codes/error_codes.rs", "w") as f:
    f.write(data)
```
</details>

5 files changed, 5 insertions, 122 deletions

diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index 5ae8b3a3e0c..2ebdac8ef7c 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -20,3 +20,4 @@ smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }
+rustc_error_codes = { path = "../librustc_error_codes" }
diff --git a/src/libsyntax_ext/asm.rs b/src/libsyntax_ext/asm.rs
index 539d777105d..5fab101957a 100644
--- a/src/libsyntax_ext/asm.rs
+++ b/src/libsyntax_ext/asm.rs
@@ -16,6 +16,8 @@ use syntax_pos::Span;
 use syntax::tokenstream::{self, TokenStream};
 use syntax::{span_err, struct_span_err};
 
+use rustc_error_codes::*;
+
 enum State {
     Asm,
     Outputs,
diff --git a/src/libsyntax_ext/deriving/default.rs b/src/libsyntax_ext/deriving/default.rs
index cfc0f3cd6cb..ab57f395f6a 100644
--- a/src/libsyntax_ext/deriving/default.rs
+++ b/src/libsyntax_ext/deriving/default.rs
@@ -9,6 +9,8 @@ use syntax::symbol::{kw, sym};
 use syntax::span_err;
 use syntax_pos::Span;
 
+use rustc_error_codes::*;
+
 pub fn expand_deriving_default(cx: &mut ExtCtxt<'_>,
                                span: Span,
                                mitem: &MetaItem,
diff --git a/src/libsyntax_ext/error_codes.rs b/src/libsyntax_ext/error_codes.rs
deleted file mode 100644
index 2bc990574f7..00000000000
--- a/src/libsyntax_ext/error_codes.rs
+++ /dev/null
@@ -1,120 +0,0 @@
-// Error messages for EXXXX errors.
-// Each message should start and end with a new line, and be wrapped to 80
-// characters.  In vim you can `:set tw=80` and use `gq` to wrap paragraphs. Use
-// `:set tw=0` to disable.
-syntax::register_diagnostics! {
-E0660: r##"
-The argument to the `asm` macro is not well-formed.
-
-Erroneous code example:
-
-```compile_fail,E0660
-asm!("nop" "nop");
-```
-
-Considering that this would be a long explanation, we instead recommend you to
-take a look at the unstable book:
-https://doc.rust-lang.org/unstable-book/language-features/asm.html
-"##,
-
-E0661: r##"
-An invalid syntax was passed to the second argument of an `asm` macro line.
-
-Erroneous code example:
-
-```compile_fail,E0661
-let a;
-asm!("nop" : "r"(a));
-```
-
-Considering that this would be a long explanation, we instead recommend you to
-take a look at the unstable book:
-https://doc.rust-lang.org/unstable-book/language-features/asm.html
-"##,
-
-E0662: r##"
-An invalid input operand constraint was passed to the `asm` macro (third line).
-
-Erroneous code example:
-
-```compile_fail,E0662
-asm!("xor %eax, %eax"
-     :
-     : "=test"("a")
-    );
-```
-
-Considering that this would be a long explanation, we instead recommend you to
-take a look at the unstable book:
-https://doc.rust-lang.org/unstable-book/language-features/asm.html
-"##,
-
-E0663: r##"
-An invalid input operand constraint was passed to the `asm` macro (third line).
-
-Erroneous code example:
-
-```compile_fail,E0663
-asm!("xor %eax, %eax"
-     :
-     : "+test"("a")
-    );
-```
-
-Considering that this would be a long explanation, we instead recommend you to
-take a look at the unstable book:
-https://doc.rust-lang.org/unstable-book/language-features/asm.html
-"##,
-
-E0664: r##"
-A clobber was surrounded by braces in the `asm` macro.
-
-Erroneous code example:
-
-```compile_fail,E0664
-asm!("mov $$0x200, %eax"
-     :
-     :
-     : "{eax}"
-    );
-```
-
-Considering that this would be a long explanation, we instead recommend you to
-take a look at the unstable book:
-https://doc.rust-lang.org/unstable-book/language-features/asm.html
-"##,
-
-E0665: r##"
-The `Default` trait was derived on an enum.
-
-Erroneous code example:
-
-```compile_fail,E0665
-#[derive(Default)]
-enum Food {
-    Sweet,
-    Salty,
-}
-```
-
-The `Default` cannot be derived on an enum for the simple reason that the
-compiler doesn't know which value to pick by default whereas it can for a
-struct as long as all its fields implement the `Default` trait as well.
-
-If you still want to implement `Default` on your enum, you'll have to do it "by
-hand":
-
-```
-enum Food {
-    Sweet,
-    Salty,
-}
-
-impl Default for Food {
-    fn default() -> Food {
-        Food::Sweet
-    }
-}
-```
-"##,
-}
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 5516f276422..07fdec05046 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -19,8 +19,6 @@ use syntax::symbol::sym;
 use syntax_expand::base::{Resolver, SyntaxExtension, SyntaxExtensionKind, MacroExpanderFn};
 use syntax_expand::proc_macro::BangProcMacro;
 
-mod error_codes;
-
 mod asm;
 mod assert;
 mod cfg;