or_patterns: implement :pat edition-specific behavior

[mark-i-m]

cc #54883 @joshtriplett

This PR implements the edition-specific behavior of :pat wrt or-patterns, as determined by the crater runs and T-lang consensus in #54883 (comment).

I believe this can unblock stabilization of or_patterns.

r? @petrochenkov

[mark-i-m]

I keep getting:

Copying stage0 rustc from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
thread 'main' panicked at 'src.symlink_metadata() failed with No such file or directory (os error 2)', src/bootstrap/lib.rs:1216:24
note: run with RUST_BACKTRACE=1 environment variable to display a backtrace
failed to run: /home/mark/rust/build/bootstrap/debug/bootstrap test --bless
Build completed unsuccessfully in 0:17:56

I've tried everything...

[petrochenkov]

Some UI tests need an update.

[mark-i-m]

For some reason, I keep getting the same bootstrapping error above. I'm unable to run any tests locally :(

[petrochenkov]

@mark-i-m
https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/bootstrap.20fails.20to.20assemble.20stage.201.20compiler

[mark-i-m]

I think CI should be passing now. CI is passing now :)

[petrochenkov]

r=me with commits squashed.

[mark-i-m]

@petrochenkov squashed.

[mark-i-m]

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author

[petrochenkov]

@bors r+

[bors]

📌 Commit fd4ae3a has been approved by petrochenkov

[rust-log-analyzer]

The job dist-armv7-linux failed! Check out the build log: (web) (plain)

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

[TIMING] StdLink { compiler: Compiler { stage: 0, host: TargetSelection { triple: "x86_64-unknown-linux-gnu", file: None } }, target_compiler: Compiler { stage: 0, host: TargetSelection { triple: "x86_64-unknown-linux-gnu", file: None } }, target: TargetSelection { triple: "x86_64-unknown-linux-gnu", file: None } } -- 0.001
[TIMING] Std { target: TargetSelection { triple: "x86_64-unknown-linux-gnu", file: None }, compiler: Compiler { stage: 0, host: TargetSelection { triple: "x86_64-unknown-linux-gnu", file: None } } } -- 76.664
Building LLVM for x86_64-unknown-linux-gnu
running: "cmake" "/checkout/src/llvm-project/llvm" "-G" "Ninja" "-DLLVM_ENABLE_ASSERTIONS=OFF" "-DLLVM_TARGETS_TO_BUILD=AArch64;ARM;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;Sparc;SystemZ;WebAssembly;X86" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR" "-DLLVM_INCLUDE_EXAMPLES=OFF" "-DLLVM_INCLUDE_TESTS=OFF" "-DLLVM_INCLUDE_DOCS=OFF" "-DLLVM_INCLUDE_BENCHMARKS=OFF" "-DLLVM_ENABLE_TERMINFO=OFF" "-DLLVM_ENABLE_LIBEDIT=OFF" "-DLLVM_ENABLE_BINDINGS=OFF" "-DLLVM_ENABLE_Z3_SOLVER=OFF" "-DLLVM_PARALLEL_COMPILE_JOBS=16" "-DLLVM_TARGET_ARCH=x86_64" "-DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-unknown-linux-gnu" "-DLLVM_ENABLE_ZLIB=ON" "-DCMAKE_EXE_LINKER_FLAGS=-Wl,-Bsymbolic -static-libstdc++" "-DLLVM_ENABLE_LIBXML2=OFF" "-DLLVM_VERSION_SUFFIX=-rust-1.50.0-nightly" "-DCMAKE_INSTALL_MESSAGE=LAZY" "-DCMAKE_C_COMPILER_LAUNCHER=sccache" "-DCMAKE_CXX_COMPILER_LAUNCHER=sccache" "-DCMAKE_C_COMPILER=cc" "-DCMAKE_CXX_COMPILER=c++" "-DCMAKE_ASM_COMPILER=cc" "-DCMAKE_C_FLAGS=-ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_CXX_FLAGS=-ffunction-sections -fdata-sections -fPIC -m64 -static-libstdc++" "-DCMAKE_INSTALL_PREFIX=/checkout/obj/build/x86_64-unknown-linux-gnu/llvm" "-DCMAKE_ASM_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_BUILD_TYPE=Release"
CMake Error: The source directory "/checkout/src/llvm-project/llvm" does not exist.
Specify --help for usage, or press the help button on the CMake GUI.
command did not execute successfully, got: exit code: 1

 finished in 0.011 seconds
 finished in 0.011 seconds
build script failed, must exit now', /cargo/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.44/src/lib.rs:885:5
failed to run: /checkout/obj/build/bootstrap/debug/bootstrap dist --host armv7-unknown-linux-gnueabihf --target armv7-unknown-linux-gnueabihf
Build completed unsuccessfully in 0:01:17

[bors]

💔 Test failed - checks-actions

[mark-i-m]

I don't understand the CI failure. It looks like llvm is missing? Seems unrelated?

[petrochenkov]

The failure looks unrelated to this PR.
@bors retry

[bors]

⌛ Testing commit 1a7d00a with merge 29e3212...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 29e3212 to master...

[Mark-Simulacrum]

This seems to have been a slight regression in instruction counts (0.5%) on the deep vector benchmark. I think it would probably be good to modify the code to lazily query the edition if we encounter a pat pattern (or, even better, one that would differ in behavior) - edition queries are relatively expensive.

[mark-i-m]

@Mark-Simulacrum Hmm... that's good to know. Yeah, I can do that. I think we will want to do something different altogether, though -- adding a new NonterminalKind for 2015/18/21 editions and their different :pats (if I understood the lang team consensus correctly). I think that should naturally handle the regression.

I can hack something together to address the regression now if you want, but I would prefer to just do the above (it might take a bit longer though; not sure I can do it before the beta branches)...

[Mark-Simulacrum]

I am not worried about this hitting beta - regression is minor. I agree that the long term planning in this area probably means we don't need a temporary fix for now.

[mark-i-m]

FYI, if someone is following up perf regressions, #80459 should resolve this regression and recently merged.