Remap Windows targets triples to their LLVM counterparts

dev-tools/gen-target-info/src/main.rs

@@ -21,6 +21,22 @@ fn generate_riscv_arch_mapping(f: &mut File, target_specs: &RustcTargetSpecs) {
     write_target_tuple_mapping(f, "RISCV_ARCH_MAPPING", &riscv_target_mapping);
 }
 
+fn generate_windows_triple_mapping(f: &mut File, target_specs: &RustcTargetSpecs) {
+    let mut windows_target_mapping = target_specs
+        .0
+        .iter()
+        .filter_map(|(target, target_spec)| {
+            let rust_target_parts = target.splitn(4, '-').collect::<Vec<_>>();
+            let os = *rust_target_parts.get(2)?;
+            (os.contains("windows") && target != &*target_spec.llvm_target)
+                .then_some((&**target, &*target_spec.llvm_target))
+        })
+        .collect::<Vec<_>>();
+    windows_target_mapping.sort_unstable_by_key(|(triple, _)| &**triple);
+    windows_target_mapping.dedup();
+    write_target_tuple_mapping(f, "WINDOWS_TRIPLE_MAPPING", &windows_target_mapping);
+}
+
 fn main() {
     let target_specs = get_target_specs_from_json();
 
@@ -34,6 +50,7 @@ fn main() {
 
     // Start generating
     generate_riscv_arch_mapping(&mut f, &target_specs);
+    generate_windows_triple_mapping(&mut f, &target_specs);
 
     // Flush the data onto disk
     f.flush().unwrap();

src/lib.rs

@@ -2189,6 +2189,17 @@ impl Build {
                         }
 
                         cmd.push_cc_arg(format!("--target={}", target).into());
+                    } else if let Ok(index) = target_info::WINDOWS_TRIPLE_MAPPING
+                        .binary_search_by_key(&target, |(target, _)| target)
+                    {
+                        cmd.args.push(
+                            format!(
+                                "--target={}-{}",
+                                target_info::WINDOWS_TRIPLE_MAPPING[index].1,
+                                rest
+                            )
+                            .into(),
+                        )
                     } else {
                         cmd.push_cc_arg(format!("--target={}", target).into());
                     }

src/target_info.rs

@@ -12,3 +12,15 @@ pub const RISCV_ARCH_MAPPING: &[(&str, &str)] = &[
     ("riscv64gc", "riscv64"),
     ("riscv64imac", "riscv64"),
 ];
+pub const WINDOWS_TRIPLE_MAPPING: &[(&str, &str)] = &[
+    ("aarch64-pc-windows-gnullvm", "aarch64-pc-windows-gnu"),
+    ("aarch64-uwp-windows-msvc", "aarch64-pc-windows-msvc"),
+    ("i686-pc-windows-gnullvm", "i686-pc-windows-gnu"),
+    ("i686-uwp-windows-gnu", "i686-pc-windows-gnu"),
+    ("i686-uwp-windows-msvc", "i686-pc-windows-msvc"),
+    ("i686-win7-windows-msvc", "i686-pc-windows-msvc"),
+    ("thumbv7a-uwp-windows-msvc", "thumbv7a-pc-windows-msvc"),
+    ("x86_64-pc-windows-gnullvm", "x86_64-pc-windows-gnu"),
+    ("x86_64-uwp-windows-gnu", "x86_64-pc-windows-gnu"),
+    ("x86_64-uwp-windows-msvc", "x86_64-pc-windows-msvc"),
+];