Added default target cpu to --print target-cpus output and updated docs

[mj10021]

Added default target cpu info as requested in issue #110647 and noted the new output in the documentation

[rustbot]

r? @b-naber

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[compiler-errors]

Can you show how this actually renders, so the reviewer doesn't need to test it themself?

[mj10021]

Can you show how this actually renders, so the reviewer doesn't need to test it themself?

Sure thing. Running rustc --print target-cpus shows:

Default cpu for this target: x86-64 Available CPUs for this target: native - Select the CPU of the current host (currently skylake). alderlake amdfam10 athlon ... 

and running rustc --print target-cpus --target i686-unknown-linux-gnu shows:

Default cpu for this target: pentium4 Available CPUs for this target: alderlake amdfam10 athlon ... 

[mj10021]

Can you show how this actually renders, so the reviewer doesn't need to test it themself?

Sure thing. Running rustc --print target-cpus shows:

Default cpu for this target: x86-64 Available CPUs for this target: native - Select the CPU of the current host (currently skylake). alderlake amdfam10 athlon ... 

and running rustc --print target-cpus --target i686-unknown-linux-gnu shows:

Default cpu for this target: pentium4 Available CPUs for this target: alderlake amdfam10 athlon ... 

Changing cpu to CPU to match the previous text

[compiler-errors]

I think the comment #110647 (comment) was asking for this to be rendered inline, as a note after the default CPU flavor. I agree with that comment. How hard is it to change the behavior to act like that instead?

[mj10021]

I think the comment #110647 (comment) was asking for this to be rendered inline, as a note after the default CPU flavor. I agree with that comment. How hard is it to change the behavior to act like that instead?

Got it, working on this now, I think I just need to pass the default target cpu into unsafe { llvm::LLVMRustPrintTargetCPUs(tm) }

[mj10021]

This is the new output:

rustc --print target-cpus

 Available CPUs for this target: native - Select the CPU of the current host (currently skylake). alderlake amdfam10 athlon athlon-4 athlon-fx athlon-mp athlon-tbird athlon-xp athlon64 athlon64-sse3 atom barcelona bdver1 bdver2 bdver3 bdver4 bonnell broadwell btver1 btver2 c3 c3-2 cannonlake cascadelake cooperlake core-avx-i core-avx2 core2 corei7 corei7-avx emeraldrapids generic geode goldmont goldmont-plus grandridge graniterapids haswell i386 i486 i586 i686 icelake-client icelake-server ivybridge k6 k6-2 k6-3 k8 k8-sse3 knl knm lakemont meteorlake nehalem nocona opteron opteron-sse3 penryn pentium pentium-m pentium-mmx pentium2 pentium3 pentium3m pentium4 pentium4m pentiumpro prescott raptorlake rocketlake sandybridge sapphirerapids sierraforest silvermont skx skylake skylake-avx512 slm tigerlake tremont westmere winchip-c6 winchip2 x86-64 - this is the default target cpu x86-64-v2 x86-64-v3 x86-64-v4 yonah znver1 znver2 znver3 znver4 

Let me know if I did something wrong with the C++, I don't have much experience there. Thanks!

[mj10021]

Maybe the text should read - this is the default target cpu for the current build target ?

[mj10021]

Maybe the text should read - this is the default target cpu for the current build target ?

also I need to capitalize CPU again lol

[mj10021]

Updated the output to
x86-64 - This is the default target CPU for the current build target (currently x86_64-unknown-linux-gnu).
and changed .expect() to .unwrap_or_else()

[b-naber]

nit: Maybe a SAFETY comment here explaining why this is ok (had to look at the docs for CString to check that it is)?

[b-naber]

Thanks. @bors r+ rollup

[bors]

📌 Commit f239cd6 has been approved by b-naber

It is now in the queue for this repository.