Update linker-plugin-lto.md to contain up to rust 1.46

[elichai]

Hi,
this is the same as #72290, if anyone has suggestions on how to automate this please say :)
otherwise, you can check the versions I've added via:

$ rustup install 1.44.0
$ rustc +1.44.0 -Vv
rustc 1.44.0 (49cae5576 2020-06-01)
binary: rustc
commit-hash: 49cae55760da0a43428eba73abcb659bb70cf2e4
commit-date: 2020-06-01
host: x86_64-unknown-linux-gnu
release: 1.44.0
LLVM version: 9.0

$ rustup install 1.45.0
$ rustc +1.45.0 -Vv
rustc 1.45.0 (5c1f21c3b 2020-07-13)
binary: rustc
commit-hash: 5c1f21c3b82297671ad3ae1e8c942d2ca92e84f2
commit-date: 2020-07-13
host: x86_64-unknown-linux-gnu
release: 1.45.0
LLVM version: 10.0

$ rustup install 1.46.0
$ rustc +stable -Vv
rustc 1.46.0 (04488afe3 2020-08-24)
binary: rustc
commit-hash: 04488afe34512aa4c33566eb16d8c912a3ae04f9
commit-date: 2020-08-24
host: x86_64-unknown-linux-gnu
release: 1.46.0
LLVM version: 10.0

[rust-highfive]

r? @GuillaumeGomez

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[GuillaumeGomez]

r? @wesleywiser

[wesleywiser]

It looks like every Rust version is only ever compatible with one Clang version, so perhaps we should change the table from an m*n matrix to a simple list of compatible versions?

[elichai]

It looks like every Rust version is only ever compatible with one Clang version, so perhaps we should change the table from an m*n matrix to a simple list of compatible versions?

Agreed, I just thought about the fact that soon(current nightly) it will require Clang 11, so I'll replace this with something like this:

Rust version	Clang Version
Rust 1.34	Clang 7
Rust 1.35	Clang 8
Rust 1.36	Clang 9

[wesleywiser]

@bors r+ rollup

[bors]

📌 Commit 2e82589 has been approved by wesleywiser

[jyn514]

if anyone has suggestions on how to automate this please say

@elichai You can automate the checking, not sure about editing the docs.

rustup toolchain install --profile minimal nightly
MINOR_VERSION=$(rustc +nightly --version | cut -d . -f 2)
LOWER_BOUND=44

llvm_version() {
    toolchain="$1"
    printf "Rust $toolchain    |    Clang "
    rustc +"$toolchain" -Vv | grep LLVM | cut -d ':' -f 2 | tr -d ' '
}

for version in `seq $LOWER_BOUND $((MINOR_VERSION - 2))`; do
    toolchain=1.$version.0
    rustup toolchain install --no-self-update --profile  minimal $toolchain >/dev/null 2>&1
    llvm_version $toolchain
done

for toolchain in beta nightly; do
    rustup toolchain install --no-self-update --profile minimal $toolchain >/dev/null 2>&1
    llvm_version $toolchain
done

Example output:

Rust 1.44.0    |    Clang 9.0
Rust 1.45.0    |    Clang 10.0
Rust 1.46.0    |    Clang 10.0
Rust beta    |    Clang 11.0
Rust nightly    |    Clang 11.0

beta/nightly is a little off, but I've spent enough time on this 😅