rebase fixes

Author: arayikhalatyan

compiler/rustc_target/src/spec/mod.rs

@@ -1996,6 +1996,7 @@ crate::target_spec_enum! {
         Windows = "windows",
         Xous = "xous",
         Zkvm = "zkvm",
+        Openvm = "openvm",
         Unknown = "unknown",
     }
     other_variant = Other;

compiler/rustc_target/src/spec/targets/riscv32im_unknown_openvm_elf.rs

@@ -1,5 +1,6 @@
 use crate::spec::{
-    Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetMetadata, TargetOptions,
+    Arch, Cc, LinkerFlavor, Lld, Os, PanicStrategy, RelocModel, Target, TargetMetadata,
+    TargetOptions,
 };
 
 pub(crate) fn target() -> Target {
@@ -13,10 +14,10 @@ pub(crate) fn target() -> Target {
             std: Some(true),
         },
         pointer_width: 32,
-        arch: "riscv32".into(),
+        arch: Arch::RiscV32,
 
         options: TargetOptions {
-            os: "openvm".into(),
+            os: Os::Openvm,
             vendor: "unknown".into(),
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),

library/std/src/sys/stdio/openvm.rs

@@ -19,7 +19,7 @@ impl io::Read for Stdin {
     fn read_buf(&mut self, mut buf: BorrowedCursor<'_>) -> io::Result<()> {
         unsafe {
             let n = abi::sys_read(fileno::STDIN, buf.as_mut().as_mut_ptr().cast(), buf.capacity());
-            buf.advance_unchecked(n);
+            buf.advance(n);
         }
         Ok(())
     }