rustdoc: add unstable latex math markdown feature

[notriddle]

Implement rust-lang/rfcs#3958

[rust-log-analyzer]

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    Checking termize v0.2.1
error[E0532]: expected unit struct, unit variant or constant, found tuple variant `TagEnd::BlockQuote`
    --> src/tools/clippy/clippy_lints/src/doc/mod.rs:1124:29
     |
1124 |                         End(TagEnd::BlockQuote) => next_range.end,
     |                             ^^^^^^^^^^^^^^^^^^ help: use the tuple variant pattern syntax instead: `TagEnd::BlockQuote(_)`
     |
    ::: /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pulldown-cmark-0.13.3/src/lib.rs:388:5
     |
 388 |     BlockQuote(Option<BlockQuoteKind>),
     |     ---------- `TagEnd::BlockQuote` defined here

error[E0532]: expected unit struct, unit variant or constant, found tuple variant `TagEnd::BlockQuote`
    --> src/tools/clippy/clippy_lints/src/doc/mod.rs:1148:17
     |
1148 |             End(TagEnd::BlockQuote) => {
     |                 ^^^^^^^^^^^^^^^^^^ help: use the tuple variant pattern syntax instead: `TagEnd::BlockQuote(_)`
     |
    ::: /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pulldown-cmark-0.13.3/src/lib.rs:388:5
     |
 388 |     BlockQuote(Option<BlockQuoteKind>),
     |     ---------- `TagEnd::BlockQuote` defined here

[RUSTC-TIMING] termize test:false 0.037
   Compiling pulldown-cmark v0.11.3
[RUSTC-TIMING] build_script_build test:false 0.081
    Checking unit-prefix v0.5.2
---
[RUSTC-TIMING] unicase test:false 0.106
error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> src/tools/clippy/clippy_lints/src/doc/doc_paragraphs_missing_punctuation.rs:59:37
    |
 59 |         Parser::new_ext(doc_string, main_body_opts() - Options::ENABLE_SMART_PUNCTUATION).into_offset_iter()
    |                                     ^^^^^^^^^^^^^^-- argument #1 of type `std::option::Option<&DocAttributeSyntax>` is missing
    |
note: function defined here
   --> compiler/rustc_resolve/src/rustdoc.rs:252:8
    |
252 | pub fn main_body_opts(doc_syntax: Option<&DocAttributeSyntax>) -> Options {
    |        ^^^^^^^^^^^^^^
help: provide the argument
    |
 59 |         Parser::new_ext(doc_string, main_body_opts(/* std::option::Option<&DocAttributeSyntax> */) - Options::ENABLE_SMART_PUNCTUATION).into_offset_iter()
    |                                                    ++++++++++++++++++++++++++++++++++++++++++++++

error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> src/tools/clippy/clippy_lints/src/doc/mod.rs:896:13
    |
896 |             main_body_opts() - Options::ENABLE_SMART_PUNCTUATION,
    |             ^^^^^^^^^^^^^^-- argument #1 of type `std::option::Option<&DocAttributeSyntax>` is missing
    |
note: function defined here
   --> compiler/rustc_resolve/src/rustdoc.rs:252:8
    |
252 | pub fn main_body_opts(doc_syntax: Option<&DocAttributeSyntax>) -> Options {
    |        ^^^^^^^^^^^^^^
help: provide the argument
    |
896 |             main_body_opts(/* std::option::Option<&DocAttributeSyntax> */) - Options::ENABLE_SMART_PUNCTUATION,
    |                            ++++++++++++++++++++++++++++++++++++++++++++++

error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> src/tools/clippy/clippy_lints/src/doc/mod.rs:924:16
    |
924 |     let opts = main_body_opts() - Options::ENABLE_SMART_PUNCTUATION;
    |                ^^^^^^^^^^^^^^-- argument #1 of type `std::option::Option<&DocAttributeSyntax>` is missing
    |
note: function defined here
   --> compiler/rustc_resolve/src/rustdoc.rs:252:8
    |
252 | pub fn main_body_opts(doc_syntax: Option<&DocAttributeSyntax>) -> Options {
    |        ^^^^^^^^^^^^^^
help: provide the argument
    |
924 |     let opts = main_body_opts(/* std::option::Option<&DocAttributeSyntax> */) - Options::ENABLE_SMART_PUNCTUATION;
    |                               ++++++++++++++++++++++++++++++++++++++++++++++

[RUSTC-TIMING] askama_derive test:false 3.764
   Compiling askama_macros v0.16.0
[RUSTC-TIMING] pulldown_cmark test:false 0.909