T-compiler Meeting Agenda 2023-08-31

--- tags: weekly, rustc type: docs --- # T-compiler Meeting Agenda 2023-08-31 ## Announcements - [Compiler Team Steering Meeting - External Dependency Timelines](https://www.google.com/calendar/event?eid=NWRmN3BmcnQ4dDFpdDFtbHVubnY5MXZqaGYgNnU1cnJ0Y2U2bHJ0djA3cGZpM2RhbWdqdXNAZw) at <time:2023-09-01T10:00:00-04:00> - Reminder: if you see a PR/issue that seems like there might be legal implications due to copyright/IP/etc, please let us know (or at least message @_**davidtwco** or @_**Wesley Wiser** so we can pass it along). ### Other WG meetings ([calendar link](https://calendar.google.com/calendar/embed?src=6u5rrtce6lrtv07pfi3damgjus%40group.calendar.google.com)) - [wg-async sprint planning](https://www.google.com/calendar/event?eid=ajVtNGowYjlzdDNhM2VwZG9vNjg4OTlzNDBfMjAyMzA4MzFUMTYwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-08-31T12:00:00-04:00> - [AFIT/RPITIT Impl Triage](https://www.google.com/calendar/event?eid=N2VsaWszdm9rY3NhdDF1MjdyMjVqajNpcWVfMjAyMzA4MzFUMjAwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-08-31T16:00:00-04:00> - [Types team meeting](https://www.google.com/calendar/event?eid=MTg3MDhpdTc3YXBqMGMzbnNxanUwdWZnazhfMjAyMzA5MDRUMTQwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-09-04T10:00:00-04:00> - [[Types] Rotating new solver / formality / polonius deep dive](https://www.google.com/calendar/event?eid=N29vMXZqbGZ1MDIxbzllMDI3dGhocWhhZmNfMjAyMzA5MDRUMTUwMDAwWiA2dTVycnRjZTZscnR2MDdwZmkzZGFtZ2p1c0Bn) at <time:2023-09-04T11:00:00-04:00> ## MCPs/FCPs - New MCPs (take a look, see if you like them!) - "Match the behavior of `strip` and `split-debuginfo` across platforms" [compiler-team#669](https://github.com/rust-lang/compiler-team/issues/669) - Old MCPs (stale MCP might be closed as per [MCP procedure](https://forge.rust-lang.org/compiler/mcp.html#when-should-major-change-proposals-be-closed)) - None at this time - Old MCPs (not seconded, take a look) - "Consistently use "region" terminology in later stages of the compiler" [compiler-team#634](https://github.com/rust-lang/compiler-team/issues/634)(last review activity: 3 months ago) - "Add a new `--build-id` flag to rustc" [compiler-team#635](https://github.com/rust-lang/compiler-team/issues/635)(last review activity: 3 months ago) - "Simplify and improve explicitness of the check-cfg syntax" [compiler-team#636](https://github.com/rust-lang/compiler-team/issues/636)(last review activity: 2 months ago) - "Add support for visionOS targets" [compiler-team#642](https://github.com/rust-lang/compiler-team/issues/642)(last review activity: 2 months ago) - "Add illumos Tier3 targets" [compiler-team#644](https://github.com/rust-lang/compiler-team/issues/644)(last review activity: about 38 days ago) - "Promote loongarch64-unknown-none* to Tier 2" [compiler-team#664](https://github.com/rust-lang/compiler-team/issues/664)(last review activity: about 13 days ago) - Pending FCP requests (check your boxes!) - "Retire the mailing list and make all decisions on zulip" [compiler-team#649](https://github.com/rust-lang/compiler-team/issues/649) - "Tracking issue for dyn upcasting coercion" [rust#65991](https://github.com/rust-lang/rust/issues/65991#issuecomment-1670127912) - "stabilize combining +bundle and +whole-archive link modifiers" [rust#113301](https://github.com/rust-lang/rust/pull/113301#issuecomment-1679904521) - "Support overriding `warnings` level for a specific lint via command line" [rust#113307](https://github.com/rust-lang/rust/pull/113307#issuecomment-1621305927) - Things in FCP (make sure you're good with it) - "Add a blanket flag to enable/disable codegen UB checks" [compiler_team#625](https://github.com/rust-lang/compiler-team/issues/625) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Add.20a.20blanket.20flag.20to.20enable.2Fdisable.20code.E2.80.A6.20compiler-team.23625)) - "Add support for Zephyr OS" [compiler_team#629](https://github.com/rust-lang/compiler-team/issues/629) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Add.20support.20for.20Zephyr.20OS.20compiler-team.23629)) - "Report all lints, even if other errors already occurred." [compiler_team#633](https://github.com/rust-lang/compiler-team/issues/633) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Report.20all.20lints.2C.20even.20if.20other.20errors.20al.E2.80.A6.20compiler-team.23633)) - "Add option to pass environment variables" [compiler_team#653](https://github.com/rust-lang/compiler-team/issues/653) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Add.20option.20to.20pass.20environment.20variables.20compiler-team.23653)) - "Add tidy rule against `issue-[0-9]+.rs` tests" [compiler_team#658](https://github.com/rust-lang/compiler-team/issues/658) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Add.20tidy.20rule.20against.20.60issue-.5B0-9.5D.2B.2Ers.60.20t.E2.80.A6.20compiler-team.23658)) - "Add `builtin:$path` option to the `-L` flag" [compiler_team#659](https://github.com/rust-lang/compiler-team/issues/659) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Add.20.60builtin.3A.24path.60.20option.20to.20the.20.60-L.60.20fl.E2.80.A6.20compiler-team.23659)) - "Support larger sizes in rmeta tables and incr comp alloc offsets" [compiler_team#666](https://github.com/rust-lang/compiler-team/issues/666) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Support.20larger.20sizes.20in.20rmeta.20tables.20and.20.E2.80.A6.20compiler-team.23666)) - "Make unknown/renamed/removed lints passed via command line respect lint levels" [compiler_team#667](https://github.com/rust-lang/compiler-team/issues/667) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Make.20unknown.2Frenamed.2Fremoved.20lints.20passed.E2.80.A6.20compiler-team.23667)) - "Condemn `asmjs-unknown-emscripten` to push a boulder up a hill for eternity" [compiler_team#668](https://github.com/rust-lang/compiler-team/issues/668) ([Zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-xxx/topic/Condemn.20.60asmjs-unknown-emscripten.60.20to.20pus.E2.80.A6.20compiler-team.23668)) - "Stabilize `PATH` option for `--print KIND=PATH`" [rust#114183](https://github.com/rust-lang/rust/pull/114183) - Accepted MCPs - "Move a `wasm32-wasi-preview1-threads` target to tier 2" [compiler-team#661](https://github.com/rust-lang/compiler-team/issues/661) - Finalized FCPs (disposition merge) - "stop adding dropck outlives requirements for `[T; 0]`" [rust#110288](https://github.com/rust-lang/rust/issues/110288) - "Allow explicit `#[repr(Rust)]`" [rust#114201](https://github.com/rust-lang/rust/pull/114201) - "style-guide: Add guidance for defining formatting for specific macros" [rust#114919](https://github.com/rust-lang/rust/pull/114919) ### WG checkins - @_*T-rust-analyzer* by @**Lukas Wirth** ([previous checkin](https://hackmd.io/XBOdBRLXR7qFfq526W7gXg#WG-checkins)): > nothing to report at this time ## Backport nominations [T-compiler stable](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Abeta-nominated+-label%3Abeta-accepted+label%3AT-compiler) / [T-compiler beta](https://github.com/rust-lang/rust/issues?q=is%3Aall+label%3Astable-nominated+-label%3Astable-accepted+label%3AT-compiler) - :beta: [1.73] "Do not forget to pass DWARF fragment information to LLVM." [rust#115139](https://github.com/rust-lang/rust/pull/115139) - Fixes (what we think is) P-critical #115113, seems to affect - also nominated for stable backport  - :beta: [1.73] "Stop emitting non-power-of-two vectors in (non-portable-SIMD) codegen" [rust#115236](https://github.com/rust-lang/rust/pull/115236) - Fixes a significant perf. regression #115212 on stable by disabling ([comment](https://github.com/rust-lang/rust/pull/115236#issuecomment-1694495552)) > It should be very safe, since it's only one line of product code, and all it does is disable #111999 in more cases, leaving those cases to use the same codepath as in 1.71. - seems that the fix is working well on nightly  - :stable: [1.72.1] "Normalize before checking if local is freeze in `deduced_param_attrs`" [rust#114948](https://github.com/rust-lang/rust/pull/114948) - Perf. regression linked to this PR (#113372) is nightly-only but this PR also fixes other perf. regressions _on stable_ (#115216, #115207) ([comment](https://github.com/rust-lang/rust/pull/114948#issuecomment-1695408078) and following)  - :stable: [1.72.1] "Do not forget to pass DWARF fragment information to LLVM." [rust#115139](https://github.com/rust-lang/rust/pull/115139) - this issue seems impacting. The fix missed the 1.72 train ([comment](https://github.com/rust-lang/rust/issues/115113#issuecomment-1690728612) so f.e. rustc 1.72.0 will be patched [by Fedora in their 1.72](https://github.com/rust-lang/rust/issues/115113#issuecomment-1688956644)) - @**apiraino** nominated: seems a good candidate to queue into an 1.72.1 - _if_ T-release will discuss a 1.72.1  - :stable: [1.72.1] "Stop emitting non-power-of-two vectors in (non-portable-SIMD) codegen" [rust#115236](https://github.com/rust-lang/rust/pull/115236)  ## PRs S-waiting-on-team [T-compiler](https://github.com/rust-lang/rust/pulls?q=is%3Aopen+label%3AS-waiting-on-team+label%3AT-compiler) - Other issues [in progress or waiting on other teams](https://hackmd.io/XYr1BrOWSiqCrl8RCWXRaQ) ## Issues of Note ### Short Summary - [3 T-compiler P-critical issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-critical) - [3 of those are unassigned](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-critical+no%3Aassignee) - [58 T-compiler P-high issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-high) - [32 of those are unassigned](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AT-compiler+label%3AP-high+no%3Aassignee) - [1 P-critical, 0 P-high, 0 P-medium, 1 P-low regression-from-stable-to-beta](https://github.com/rust-lang/rust/labels/regression-from-stable-to-beta) - [0 P-critical, 0 P-high, 2 P-medium, 2 P-low regression-from-stable-to-nightly](https://github.com/rust-lang/rust/labels/regression-from-stable-to-nightly) - [4 P-critical, 38 P-high, 100 P-medium, 18 P-low regression-from-stable-to-stable](https://github.com/rust-lang/rust/labels/regression-from-stable-to-stable) ### P-critical [T-compiler](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-compiler) - "ICE: unexpected initial operand type." [rust#114858](https://github.com/rust-lang/rust/issues/114858) - IIUC (@**apiraino**) the issue should be addressed (at least partially) by [rust#115215](https://github.com/rust-lang/rust/pull/115215) ([comment](https://github.com/rust-lang/rust/issues/114858#issuecomment-1697446671)) - "ScalarReplacementOfAggregates causes rustc to emit invalid LLVM debuginfo (and sometimes rustc segfaults)" [rust#115113](https://github.com/rust-lang/rust/issues/115113) - Fixed by [rust#115139](https://github.com/rust-lang/rust/pull/115139) - "Failed assert `2 != 2` after update to LLVM 17" [rust#115385](https://github.com/rust-lang/rust/issues/115385) - Not assigned, opened yesterday - has eyes on it, ex. [this bisection](https://github.com/rust-lang/rust/issues/115385#issuecomment-1699916149) from @**lqd** [T-types](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-types) - "RPIT hidden types can be ill-formed" [rust#114728](https://github.com/rust-lang/rust/issues/114728) - UB originated in #94081 - handled by @**Michael Goulet (compiler-errors)** in [rust#114740](https://github.com/rust-lang/rust/pull/114740) - also #114933 by @**aliemjay** [T-rustdoc](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AP-critical+label%3AT-rustdoc) - "ICE when building documentation: DefId(20:797 ...) does not have a "object_lifetime_default"" [rust#115179](https://github.com/rust-lang/rust/issues/115179) - reported a crate cannot generate documentation anymore, at least since 1.72.0 - regressed in #107637 - handled by @_**León Orell Liehr (fmease)** in [rust#115276](https://github.com/rust-lang/rust/pull/115276) ### P-high regressions [P-high beta regressions](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3Aregression-from-stable-to-beta+label%3AP-high+-label%3AT-infra+-label%3AT-libs+-label%3AT-libs-api+-label%3AT-release+-label%3AT-rustdoc+-label%3AT-core) - No `P-high` beta regressions this time. [Unassigned P-high nightly regressions](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3Aregression-from-stable-to-nightly+label%3AP-high+no%3Aassignee+-label%3AT-infra+-label%3AT-libs+-label%3AT-libs-api+-label%3AT-release+-label%3AT-rustdoc+-label%3AT-core+) - No unassigned `P-high` nightly regressions this time. ## Performance logs > [triage logs for 2023--08-29](https://github.com/rust-lang/rustc-perf/blob/master/triage/2023-08-29.md) A fairly quiet week, with improvements exceeding a small scattering of regressions. Memory usage and artifact size held fairly steady across the week, with no regressions or improvements. Triage done by **@simulacrum**. Revision range: [d4a881e1433cd10e424843353e1f939f5a798f4e..cedbe5c715c1fa9359683c5f108bed2054ac258b](https://perf.rust-lang.org/?start=d4a881e1433cd10e424843353e1f939f5a798f4e&end=cedbe5c715c1fa9359683c5f108bed2054ac258b&absolute=false&stat=instructions%3Au) **Summary**: | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | 1.6% | [0.3%, 2.2%] | 6 | | Regressions (secondary) | 1.4% | [0.8%, 1.9%] | 19 | | Improvements (primary) | -1.0% | [-8.0%, -0.3%] | 70 | | Improvements (secondary) | -1.6% | [-4.2%, -0.2%] | 56 | | All (primary) | -0.8% | [-8.0%, 2.2%] | 76 | 2 Regressions, 3 Improvements, 2 Mixed; 0 of them in rollups 108 artifact comparisons made in total #### Regressions rustdoc: Add lint `redundant_explicit_links` [#113167](https://github.com/rust-lang/rust/pull/113167) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=f32ced648191cc67efdf6001585687ad22ed00d2&end=9c699a40cc2680b876c32ee69b402ee34bf7989a&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:----:|:------------:|:-----:| | Regressions (primary) | 0.7% | [0.4%, 0.9%] | 7 | | Regressions (secondary) | - | - | 0 | | Improvements (primary) | - | - | 0 | | Improvements (secondary) | - | - | 0 | | All (primary) | 0.7% | [0.4%, 0.9%] | 7 | Small regression in libc compilation, primarily incremental non-doc scenarios. Unclear cause but sufficiently limited in scope that further investigation is not warranted. Fix races conditions with `SyntaxContext` decoding [#115082](https://github.com/rust-lang/rust/pull/115082) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=aa5dbee3ebff8703456e8be3b5fb368fc68fe0d1&end=b60e31b673b0d36c50f8e0a3b6f8f077221d983d&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:----:|:------------:|:-----:| | Regressions (primary) | 0.3% | [0.2%, 0.3%] | 4 | | Regressions (secondary) | 0.3% | [0.3%, 0.4%] | 7 | | Improvements (primary) | - | - | 0 | | Improvements (secondary) | - | - | 0 | | All (primary) | 0.3% | [0.2%, 0.3%] | 4 | Some small regressions, but this is a correctness fix for parallel compilation so warranted. (Parallel compilation is not on here but the fix affects both non-parallel and parallel scenarios). #### Improvements Speed up compilation of `type-system-chess` [#114611](https://github.com/rust-lang/rust/pull/114611) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=fe3eae3f310b2f709aa5b39d76a94fc1ea843854&end=a1e1dba9cc40a90409bccb8b19e359c4bdf573e5&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | - | - | 0 | | Regressions (secondary) | - | - | 0 | | Improvements (primary) | -1.7% | [-1.7%, -1.7%] | 1 | | Improvements (secondary) | -2.2% | [-4.2%, -0.7%] | 28 | | All (primary) | -1.7% | [-1.7%, -1.7%] | 1 | > Perf results look good, various small improvements in secondary benchmarks. > The real driver was the type-system-chess program I mentioned above, where > the walltime and max-rss changes were both about -85% when I measured them > locally. (https://github.com/rust-lang/rust/pull/114611#issuecomment-1670713067) Add MIR validation for unwind out from nounwind functions + fixes to make validation pass [#113124](https://github.com/rust-lang/rust/pull/113124) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=b6ab01a7131481b52131a9bd814dc8084052f643&end=ff55fa30267d7963146c52026b4f4f5396484675&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | - | - | 0 | | Regressions (secondary) | - | - | 0 | | Improvements (primary) | -0.7% | [-1.1%, -0.5%] | 6 | | Improvements (secondary) | -0.3% | [-0.6%, -0.2%] | 3 | | All (primary) | -0.7% | [-1.1%, -0.5%] | 6 | Update x64 Linux host compiler to LLVM 17 [#114297](https://github.com/rust-lang/rust/pull/114297) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9bd60a60cefdddca1f507083dda37e1664b295c5&end=0b31792ef1c15538b07c7b83585dc2fb371c239f&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | - | - | 0 | | Regressions (secondary) | - | - | 0 | | Improvements (primary) | -0.6% | [-1.0%, -0.2%] | 41 | | Improvements (secondary) | -0.9% | [-1.5%, -0.2%] | 22 | | All (primary) | -0.6% | [-1.0%, -0.2%] | 41 | #### Mixed Remove references in VarDebugInfo [#114904](https://github.com/rust-lang/rust/pull/114904) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=07688726805d5db0a4bca445a6651d09708041ea&end=ccc3ac0cae0d901a360c4f93f6d41d87ed459d20&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | 0.8% | [0.3%, 1.3%] | 10 | | Regressions (secondary) | 1.4% | [1.3%, 1.4%] | 4 | | Improvements (primary) | -1.0% | [-7.3%, -0.3%] | 32 | | Improvements (secondary) | -2.1% | [-2.4%, -1.6%] | 4 | | All (primary) | -0.6% | [-7.3%, 1.3%] | 42 | Fixed a bug in codegen. The regressions appear to be within noise range for the relevant benchmarks. Add a new helper to avoid calling io::Error::kind [#115228](https://github.com/rust-lang/rust/pull/115228) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c5035271acc7e140893c1dcdb5a83bf4ddf04593&end=9334ec93541fd6963a3bfa2d2d09e3e33ac93131&stat=instructions:u) | (instructions:u) | mean | range | count | |:------------------------:|:-----:|:--------------:|:-----:| | Regressions (primary) | 0.3% | [0.3%, 0.3%] | 1 | | Regressions (secondary) | - | - | 0 | | Improvements (primary) | -0.6% | [-0.8%, -0.5%] | 3 | | Improvements (secondary) | - | - | 0 | | All (primary) | -0.4% | [-0.8%, 0.3%] | 4 | Regression is within noise range of the relevant benchmark. ## Nominated Issues [T-compiler](https://github.com/rust-lang/rust/issues?q=is%3Aopen+label%3AI-compiler-nominated) - "SIGILL Illegal Instruction on PPC64" [rust#110278](https://github.com/rust-lang/rust/issues/110278) - the `xvor` instruction (an AltiVec optimisation) in cargo and rustup-init binaries prevents anything to compile under PPC64 (POWER5+ class) ([comment](https://github.com/rust-lang/rust/issues/110278#issuecomment-1692479965)) - Issue was reported for Tier 2 family of platform (`powerpc64-unknown-linux-gnu`, discontinued in 2019, only about that particular server model, see [comment](https://github.com/rust-lang/rust/issues/110278#issuecomment-1692479965)) but is also visible in more recent POWER architectures - nomination by @**Josh Stone (cuviper)** Do we actually support this/these arch(s)? - (issue reporter seems for now to be able to handle the situation by crosscompiling without that AltiVec opt.) [RFC](https://github.com/rust-lang/rfcs/issues?q=is%3Aopen+label%3AI-compiler-nominated) - No I-compiler-nominated RFCs this time. ### Oldest PRs waiting for review - "Rebased: Mark drop calls in landing pads cold instead of noinline" [rust#102099](https://github.com/rust-lang/rust/pull/102099) - probably needs a second look from someone ([comment](https://github.com/rust-lang/rust/pull/102099#issuecomment-1671103591)) - "Fix ICE when trying to convert `ConstKind::Error` to usize" [rust#113712](https://github.com/rust-lang/rust/pull/113712)(last review activity: about 46 days ago) - cc: @**uwu** - "rustc_llvm: Link to libkstat on Solaris/SPARC" [rust#114224](https://github.com/rust-lang/rust/pull/114224)(last review activity: about 32 days ago) - cc: @**Josh Stone (cuviper)** (probably needs a bit of SPARC/Solaris context) - "Pretty-print argument-position impl trait to name it." [rust#113955](https://github.com/rust-lang/rust/pull/113955)(last review activity: about 31 days ago) - cc @**Waffle Lapkin** ## Next week's WG checkins - @_*WG-rustc-dev-guide* by @**Santiago Pastorino** and @**Yuki Okushi|217081** Next meetings' agenda draft: `https://hackmd.io/Ly5571uCSUSm6Uib-f5K8Q`

Syntax	Example	Reference
# Header	Header	基本排版
- Unordered List	Unordered List
1. Ordered List	Ordered List
- [ ] Todo List	Todo List
> Blockquote	Blockquote
Bold font	Bold font
Italics font	Italics font
~~Strikethrough~~	~~Strikethrough~~
19^th^	19^th
H~2~O	H₂O
++Inserted text++	Inserted text
==Marked text==	Marked text
[link text](https:// "title")	Link
![image alt](https:// "title")	Image
`Code`	`Code`	在筆記中貼入程式碼
```javascript var i = 0; ```	`var i = 0;`
:smile:		Emoji list
{%youtube youtube_id %}	Externals
$L^aT_eX$	L^aT_eX
:::info This is a alert area. :::	This is a alert area.