Use object crate's wasm feature

Author: alexcrichton

Cargo.lock

@@ -2608,6 +2608,7 @@ dependencies = [
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
  "ruzstd",
+ "wasmparser",
 ]
 
 [[package]]
@@ -6035,6 +6036,16 @@ version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ca6ad05a4870b2bf5fe995117d3728437bd27d7cd5f06f13c17443ef369775a1"
 
+[[package]]
+name = "wasmparser"
+version = "0.118.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "95ee9723b928e735d53000dec9eae7b07a60e490c85ab54abb66659fc61bfcd9"
+dependencies = [
+ "indexmap",
+ "semver",
+]
+
 [[package]]
 name = "web-sys"
 version = "0.3.61"

compiler/rustc_codegen_ssa/Cargo.toml

@@ -48,7 +48,7 @@ libc = "0.2.50"
 [dependencies.object]
 version = "0.32.1"
 default-features = false
-features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write"]
+features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write", "wasm"]
 
 [target.'cfg(windows)'.dependencies.windows]
 version = "0.48.0"

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -16,7 +16,6 @@ use rustc_metadata::creader::MetadataLoader;
 use rustc_metadata::fs::METADATA_FILENAME;
 use rustc_metadata::EncodedMetadata;
 use rustc_serialize::leb128;
-use rustc_serialize::{opaque::MemDecoder, Decoder};
 use rustc_session::Session;
 use rustc_span::sym;
 use rustc_target::abi::Endian;
@@ -64,8 +63,8 @@ impl MetadataLoader for DefaultMetadataLoader {
                         .map_err(|e| format!("failed to parse rlib '{}': {}", path.display(), e))?;
                     if target.is_like_aix {
                         return get_metadata_xcoff(path, data);
-                    } else if target.is_like_wasm {
-                        return get_metadata_wasm(data, ".rmeta");
+                    // } else if target.is_like_wasm {
+                    //     return get_metadata_wasm(data, ".rmeta");
                     } else {
                         return search_for_section(path, data, ".rmeta");
                     }
@@ -675,31 +674,3 @@ pub fn create_metadata_file_for_wasm(data: &[u8], section_name: &[u8]) -> Vec<u8
     append_custom_section(section_name, data);
     bytes
 }
-
-// NB: see documentation on `create_metadata_file_for_wasm` above for
-// particulars on the wasm format.
-fn get_metadata_wasm<'a>(data: &'a [u8], expected_section_name: &str) -> Result<&'a [u8], String> {
-    let data = data
-        .strip_prefix(b"\0asm\x01\0\0\0")
-        .ok_or_else(|| format!("metadata has an invalid wasm header"))?;
-
-    let mut decoder = MemDecoder::new(data, 0);
-    let mut next_custom_section = |expected_section_name: &str| {
-        if decoder.read_u8() != 0 {
-            return Err(format!("metadata did not start with a custom section"));
-        }
-        let section_len = leb128::read_usize_leb128(&mut decoder);
-
-        let section_start = decoder.position();
-        let mut section = MemDecoder::new(decoder.read_raw_bytes(section_len), 0);
-        let name_len = leb128::read_usize_leb128(&mut section);
-        let section_name = section.read_raw_bytes(name_len);
-        if section_name != expected_section_name.as_bytes() {
-            return Err(format!("unexpected section name in metadata object"));
-        }
-        Ok(&data[section_start + section.position()..][..section.remaining()])
-    };
-
-    next_custom_section("linking")?;
-    next_custom_section(expected_section_name)
-}