MCP rust-lang#705: Provide the option `-Zsymbol-mangling-version=hash…

…ed` to shorten symbol names by replacing them with a digest.

Enrich test cases

compiler/rustc_session/src/config.rs

@@ -347,6 +347,7 @@ impl SwitchWithOptPath {
 pub enum SymbolManglingVersion {
     Legacy,
     V0,
+    Hashed,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Hash)]
@@ -2689,17 +2690,37 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
 
     // Check for unstable values of `-C symbol-mangling-version`.
     // This is what prevents them from being used on stable compilers.
-    match cg.symbol_mangling_version {
-        // Stable values:
-        None | Some(SymbolManglingVersion::V0) => {}
-        // Unstable values:
-        Some(SymbolManglingVersion::Legacy) => {
+    match (cg.symbol_mangling_version, unstable_opts.symbol_mangling_version) {
+        (Some(smv_c), Some(smv_z)) if smv_c != smv_z => {
+            early_dcx.early_fatal(
+                "incompatible values passed for `-C symbol-mangling-version` \
+                and `-Z symbol-mangling-version`",
+            );
+        }
+
+        (Some(SymbolManglingVersion::Legacy), _) => {
             if !unstable_opts.unstable_options {
                 early_dcx.early_fatal(
                     "`-C symbol-mangling-version=legacy` requires `-Z unstable-options`",
                 );
             }
         }
+        (Some(SymbolManglingVersion::Hashed), _) => {
+            if !unstable_opts.unstable_options {
+                early_dcx.early_fatal(
+                    "`-C symbol-mangling-version=hashed` requires `-Z unstable-options`",
+                );
+            }
+        }
+
+        // Stable values:
+        (Some(SymbolManglingVersion::V0), _) => {}
+        (None, None) => {}
+
+        // Unstable values:
+        (None, smv) => {
+            cg.symbol_mangling_version = smv;
+        }
     }
 
     // Check for unstable values of `-C instrument-coverage`.
@@ -2741,6 +2762,12 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
                 );
             }
             Some(SymbolManglingVersion::V0) => {}
+            Some(SymbolManglingVersion::Hashed) => {
+                early_dcx.early_warn(
+                    "-C instrument-coverage requires symbol mangling version `v0`, \
+                    but `-Z symbol-mangling-version=hashed` was specified",
+                );
+            }
         }
     }
 

compiler/rustc_session/src/options.rs

@@ -406,7 +406,8 @@ mod desc {
     pub const parse_switch_with_opt_path: &str =
         "an optional path to the profiling data output directory";
     pub const parse_merge_functions: &str = "one of: `disabled`, `trampolines`, or `aliases`";
-    pub const parse_symbol_mangling_version: &str = "either `legacy` or `v0` (RFC 2603)";
+    pub const parse_symbol_mangling_version: &str =
+        "one of: `legacy`, `v0` (RFC 2603), or `hashed`";
     pub const parse_src_file_hash: &str = "either `md5` or `sha1`";
     pub const parse_relocation_model: &str =
         "one of supported relocation models (`rustc --print relocation-models`)";
@@ -1179,6 +1180,7 @@ mod parse {
         *slot = match v {
             Some("legacy") => Some(SymbolManglingVersion::Legacy),
             Some("v0") => Some(SymbolManglingVersion::V0),
+            Some("hashed") => Some(SymbolManglingVersion::Hashed),
             _ => return false,
         };
         true
@@ -1490,7 +1492,7 @@ options! {
         "tell the linker which information to strip (`none` (default), `debuginfo` or `symbols`)"),
     symbol_mangling_version: Option<SymbolManglingVersion> = (None,
         parse_symbol_mangling_version, [TRACKED],
-        "which mangling version to use for symbol names ('legacy' (default) or 'v0')"),
+        "which mangling version to use for symbol names ('legacy' (default), 'v0', or 'hashed')"),
     target_cpu: Option<String> = (None, parse_opt_string, [TRACKED],
         "select target processor (`rustc --print target-cpus` for details)"),
     target_feature: String = (String::new(), parse_target_feature, [TRACKED],
@@ -1880,6 +1882,9 @@ written to standard error output)"),
         "prefer dynamic linking to static linking for staticlibs (default: no)"),
     strict_init_checks: bool = (false, parse_bool, [TRACKED],
         "control if mem::uninitialized and mem::zeroed panic on more UB"),
+    symbol_mangling_version: Option<SymbolManglingVersion> = (None,
+        parse_symbol_mangling_version, [TRACKED],
+        "which mangling version to use for symbol names ('legacy' (default), 'v0', or 'hashed')"),
     #[rustc_lint_opt_deny_field_access("use `Session::teach` instead of this field")]
     teach: bool = (false, parse_bool, [TRACKED],
         "show extended diagnostic help (default: no)"),

compiler/rustc_symbol_mangling/src/hashed.rs

@@ -0,0 +1,27 @@
+use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
+use rustc_hir::def_id::CrateNum;
+use rustc_middle::ty::{Instance, TyCtxt};
+
+pub(super) fn mangle<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    instance: Instance<'tcx>,
+    instantiating_crate: Option<CrateNum>,
+    full_mangling_name: impl FnOnce() -> String,
+) -> String {
+    // A generic function of an upstream library can be included in a dylib that depends on it.
+    // In this case, `instantiating-crate name` is used to replace `crate name`.
+    // If hash conflicats with other APIs in dylib, the method can be detected immediately.
+    // Based on `instantiating-crate name`, symbol conflicts with other dylibs are avoided.
+    let crate_num =
+        if let Some(krate) = instantiating_crate { krate } else { instance.def_id().krate };
+    let crate_name = tcx.crate_name(crate_num);
+    let crate_name = crate_name.as_str();
+
+    let hash = tcx.with_stable_hashing_context(|mut hcx| {
+        let mut hasher = StableHasher::new();
+        full_mangling_name().hash_stable(&mut hcx, &mut hasher);
+        hasher.finish::<Hash64>().as_u64()
+    });
+
+    format!("_RNxC{}{crate_name}17H{hash:016x}", crate_name.len())
+}

compiler/rustc_symbol_mangling/src/lib.rs

@@ -111,6 +111,7 @@ use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, Instance, TyCtxt};
 use rustc_session::config::SymbolManglingVersion;
 
+mod hashed;
 mod legacy;
 mod v0;
 
@@ -265,6 +266,9 @@ fn compute_symbol_name<'tcx>(
     let symbol = match mangling_version {
         SymbolManglingVersion::Legacy => legacy::mangle(tcx, instance, instantiating_crate),
         SymbolManglingVersion::V0 => v0::mangle(tcx, instance, instantiating_crate),
+        SymbolManglingVersion::Hashed => hashed::mangle(tcx, instance, instantiating_crate, || {
+            v0::mangle(tcx, instance, instantiating_crate)
+        }),
     };
 
     debug_assert!(

tests/run-make/symbol-mangling-version/Makefile

@@ -0,0 +1,47 @@
+# ignore-cross-compile
+include ../tools.mk
+
+# ignore-windows-msvc
+
+NM=nm -D
+RLIB_NAME=liba_rlib.rlib
+DYLIB_NAME=liba_dylib.so
+SO_NAME=libb_dylib.so
+BIN_NAME=b_bin
+
+ifeq ($(UNAME),Darwin)
+NM=nm -gU
+RLIB_NAME=liba_rlib.rlib
+DYLIB_NAME=liba_dylib.dylib
+SO_NAME=libb_dylib.dylib
+BIN_NAME=b_bin
+endif
+
+ifdef IS_WINDOWS
+NM=nm -g
+RLIB_NAME=liba_rlib.dll.a
+DYLIB_NAME=liba_dylib.dll
+SO_NAME=libb_dylib.dll
+BIN_NAME=b_bin.exe
+endif
+
+all:
+	$(RUSTC) -C prefer-dynamic -Z symbol-mangling-version=hashed -C metadata=foo a_dylib.rs
+	$(RUSTC) -C prefer-dynamic -Z symbol-mangling-version=hashed -C metadata=bar a_rlib.rs
+	$(RUSTC) -C prefer-dynamic -L $(TMPDIR) b_dylib.rs
+	$(RUSTC) -C prefer-dynamic -L $(TMPDIR) b_bin.rs
+
+    # Check hashed symbol name
+
+	[ "$$($(NM) $(TMPDIR)/$(DYLIB_NAME) | grep -c hello)" -eq "0" ]
+	[ "$$($(NM) $(TMPDIR)/$(DYLIB_NAME) | grep a_dylib17H | grep -c ' T ')" -eq "1" ]
+
+	[ "$$($(NM) $(TMPDIR)/$(SO_NAME) | grep b_dylib | grep -c hello)" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(SO_NAME) | grep a_rlib17H | grep -c ' T ')" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(SO_NAME) | grep a_dylib17H | grep -c ' U ')" -eq "1" ]
+
+	[ "$$($(NM) $(TMPDIR)/$(BIN_NAME) | grep a_rlib17H | grep -c ' U ')" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(BIN_NAME) | grep a_dylib17H | grep -c ' U ')" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(BIN_NAME) | grep b_dylib | grep hello | grep -c ' U ')" -eq "1" ]
+
+	$(call RUN,$(BIN_NAME))

tests/run-make/symbol-mangling-version/a_dylib.rs

@@ -0,0 +1,4 @@
+#![crate_type="dylib"]
+pub fn hello() {
+    println!("hello dylib");
+}

tests/run-make/symbol-mangling-version/a_rlib.rs

@@ -0,0 +1,5 @@
+#![crate_type="rlib"]
+
+pub fn hello() {
+    println!("hello rlib");
+}

tests/run-make/symbol-mangling-version/b_bin.rs

@@ -0,0 +1,9 @@
+extern crate a_rlib;
+extern crate a_dylib;
+extern crate b_dylib;
+
+fn main() {
+    a_rlib::hello();
+    a_dylib::hello();
+    b_dylib::hello();
+}

tests/run-make/symbol-mangling-version/b_dylib.rs

@@ -0,0 +1,9 @@
+#![crate_type="dylib"]
+
+extern crate a_rlib;
+extern crate a_dylib;
+
+pub fn hello() {
+    a_rlib::hello();
+    a_dylib::hello();
+}

tests/ui/symbol-mangling-version/bad-value.bad.stderr

@@ -1,2 +1,2 @@
-error: incorrect value `bad-value` for codegen option `symbol-mangling-version` - either `legacy` or `v0` (RFC 2603) was expected
+error: incorrect value `bad-value` for codegen option `symbol-mangling-version` - one of: `legacy`, `v0` (RFC 2603), or `hashed` was expected
 

tests/ui/symbol-mangling-version/bad-value.blank.stderr

@@ -1,2 +1,2 @@
-error: incorrect value `` for codegen option `symbol-mangling-version` - either `legacy` or `v0` (RFC 2603) was expected
+error: incorrect value `` for codegen option `symbol-mangling-version` - one of: `legacy`, `v0` (RFC 2603), or `hashed` was expected
 

tests/ui/symbol-mangling-version/bad-value.no-value.stderr

@@ -1,2 +1,2 @@
-error: codegen option `symbol-mangling-version` requires either `legacy` or `v0` (RFC 2603) (C symbol-mangling-version=<value>)
+error: codegen option `symbol-mangling-version` requires one of: `legacy`, `v0` (RFC 2603), or `hashed` (C symbol-mangling-version=<value>)
 

tests/ui/symbol-mangling-version/unstable.hashed.stderr

@@ -0,0 +1,2 @@
+error: `-C symbol-mangling-version=hashed` requires `-Z unstable-options`
+

tests/ui/symbol-mangling-version/unstable.rs

@@ -1,6 +1,9 @@
-// revisions: legacy legacy-ok
+// revisions: legacy legacy-ok hashed hashed-ok
 // [legacy] compile-flags: -Csymbol-mangling-version=legacy
 // [legacy-ok] check-pass
 // [legacy-ok] compile-flags: -Zunstable-options -Csymbol-mangling-version=legacy
+// [hashed] compile-flags: -Csymbol-mangling-version=hashed
+// [hashed-ok] check-pass
+// [hashed-ok] compile-flags: -Zunstable-options -Csymbol-mangling-version=hashed
 
 fn main() {}