Add new x86_64-win7-windows-msvc target

Author: roblabla

compiler/rustc_target/src/spec/mod.rs

@@ -1604,6 +1604,7 @@ supported_targets! {
     ("aarch64-uwp-windows-msvc", aarch64_uwp_windows_msvc),
     ("x86_64-pc-windows-msvc", x86_64_pc_windows_msvc),
     ("x86_64-uwp-windows-msvc", x86_64_uwp_windows_msvc),
+    ("x86_64-win7-windows-msvc", x86_64_win7_windows_msvc),
     ("i686-pc-windows-msvc", i686_pc_windows_msvc),
     ("i686-uwp-windows-msvc", i686_uwp_windows_msvc),
     ("i586-pc-windows-msvc", i586_pc_windows_msvc),

compiler/rustc_target/src/spec/targets/x86_64_win7_windows_msvc.rs

@@ -0,0 +1,18 @@
+use crate::spec::{base, Target};
+
+pub fn target() -> Target {
+    let mut base = base::windows_msvc::opts();
+    base.cpu = "x86-64".into();
+    base.plt_by_default = false;
+    base.max_atomic_width = Some(64);
+    base.vendor = "win7".into();
+
+    Target {
+        llvm_target: "x86_64-win7-windows-msvc".into(),
+        pointer_width: 64,
+        data_layout: "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+            .into(),
+        arch: "x86_64".into(),
+        options: base,
+    }
+}

src/doc/rustc/src/SUMMARY.md

@@ -55,6 +55,7 @@
     - [\*-unknown-uefi](platform-support/unknown-uefi.md)
     - [wasm32-wasi-preview1-threads](platform-support/wasm32-wasi-preview1-threads.md)
     - [wasm64-unknown-unknown](platform-support/wasm64-unknown-unknown.md)
+    - [\*-win7-windows-msvc](platform-support/win7-windows-msvc.md)
     - [x86_64-fortanix-unknown-sgx](platform-support/x86_64-fortanix-unknown-sgx.md)
     - [x86_64-unknown-none](platform-support/x86_64-unknown-none.md)
     - [x86_64h-apple-darwin](platform-support/x86_64h-apple-darwin.md)

src/doc/rustc/src/platform-support.md

@@ -351,6 +351,7 @@ target | std | host | notes
 [`x86_64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 64-bit OpenBSD
 `x86_64-uwp-windows-gnu` | ✓ |  |
 `x86_64-uwp-windows-msvc` | ✓ |  |
+[`x86_64-win7-windows-msvc`](platform-support/win7-windows-msvc.md) | ✓ |   | 64-bit Windows 7 support
 `x86_64-wrs-vxworks` | ? |  |
 [`x86_64h-apple-darwin`](platform-support/x86_64h-apple-darwin.md) | ✓ | ✓ | macOS with late-gen Intel (at least Haswell)
 

src/doc/rustc/src/platform-support/win7-windows-msvc.md

@@ -0,0 +1,44 @@
+# *-win7-windows-msvc
+
+**Tier: 3**
+
+Windows targets continuing support of windows7.
+
+## Target maintainers
+
+- @roblabla
+
+## Requirements
+
+This target supports full the entirety of std. This is automatically tested
+every night on private infrastructure. Host tools may also work, though those
+are not currently tested.
+
+Those targets follow Windows calling convention for extern "C".
+
+Like with any other Windows target created binaries are in PE format.
+
+## Building the target
+
+You can build Rust with support for the targets by adding it to the target list in config.toml:
+
+```toml
+[build]
+build-stage = 1
+target = [ "x86_64-win7-windows-msvc" ]
+```
+
+## Building Rust programs
+
+Rust does not yet ship pre-compiled artifacts for this target. To compile for
+this target, you will either need to build Rust with the target enabled (see
+"Building the target" above), or build your own copy of `core` by using
+`build-std` or similar.
+
+## Testing
+
+Created binaries work fine on Windows or Wine using native hardware.
+
+## Cross-compilation toolchains and C code
+
+Compatible C code can be built with either MSVC's `cl.exe` or LLVM's clang-cl.