test: avoid hardcoded target spec json

[weihanglo]

Read a real target spec JSON so we no longer need to hardcode
a target spec JSON here.
Cargo itself should not care about the spec schema.

Let's stop bothering compiler contributors.

• Make target pointer width in target json an integer rust#144443
• Rollup of 20 pull requests rust#145764 (comment)
• #t-compiler > Is it possible to add a commit to a submodule? @ 💬

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[bjorn3]

Instead of having a specific target json file would an option be to ask rustc for the target json file of an existing target and just remove the is-builtim flag before passing it back to cargo? That way it will remain correct even if the target json spec format changes in any way other than renaming the is-builtin field.

[weihanglo]

@bjorn3 good idea, though where is the is-builtin flag you were talking about?

$ rustc +nightly --print target-spec-json -Zunstable-options --target wasm32-unknown-unknown
{
  "arch": "wasm32",
  "binary-format": "wasm",
  "crt-objects-fallback": "true",
  "data-layout": "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-i128:128-n32:64-S128-ni:1:10:20",
  "dll-prefix": "",
  "dll-suffix": ".wasm",
  "dynamic-linking": true,
  "eh-frame-header": false,
  "emit-debug-gdb-scripts": false,
  "exe-suffix": ".wasm",
  "generate-arange-section": false,
  "has-thread-local": true,
  "is-like-wasm": true,
  "limit-rdylib-exports": false,
  "linker": "rust-lld",
  "linker-flavor": "wasm-lld",
  "linker-is-gnu": false,
  "lld-flavor": "wasm",
  "llvm-target": "wasm32-unknown-unknown",
  "max-atomic-width": 64,
  "metadata": {
    "description": "WebAssembly",
    "host_tools": false,
    "std": true,
    "tier": 2
  },
  "only-cdylib": true,
  "os": "unknown",
  "panic-strategy": "abort",
  "pre-link-args": {
    "wasm-lld": [
      "-z",
      "stack-size=1048576",
      "--stack-first",
      "--allow-undefined",
      "--no-demangle",
      "--no-entry"
    ],
    "wasm-lld-cc": [
      "-Wl,-z",
      "-Wl,stack-size=1048576",
      "-Wl,--stack-first",
      "-Wl,--allow-undefined",
      "-Wl,--no-demangle",
      "--target=wasm32-unknown-unknown",
      "-Wl,--no-entry"
    ]
  },
  "relocation-model": "static",
  "singlethread": true,
  "target-family": [
    "wasm"
  ],
  "target-pointer-width": "32",
  "tls-model": "local-exec"
}

[weihanglo]

I should go ahead and remove _all" hardcoded target spec jsons.

[bjorn3]

I guess rustc itself nowadays already filters out the is-builtin field before printing.

[WaffleLapkin]

This matches the changes that I did locally (i.e. it fixes all the places that I fixed).

[weihanglo]

Run rustup update --no-self-update stable
info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'
error: failed to download file error=Reqwest(reqwest::Error { kind: Request, url: "https://static.rust-lang.org/dist/channel-rust-stable.toml.sha256", source: hyper_util::client::legacy::Error(Connect, Custom { kind: Other, error: Os { code: 104, kind: ConnectionReset, message: "Connection reset by peer" } }) })
error: could not download file from 'https://static.rust-lang.org/dist/channel-rust-stable.toml.sha256' to '/home/runner/.rustup/tmp/y2jjoktwl9rzp757_file': error downloading file: error sending request for url (https://static.rust-lang.org/dist/channel-rust-stable.toml.sha256): client error (Connect): Connection reset by peer (os error 104)

Retried an succeeded. Merging.