Auto merge of #65435 - michaelwoerister:fix-issue-64153, r=alexcrichton

Fix #64153

This PR changes how the compiler detects if an object file from an upstream crate is a Rust object file or not. Instead of checking if the name starts with the crate name and ends with `.o` (which is not always the case, as described in #64153), it now just checks if the filename ends with `.rcgu.o`.

This fixes #64153. However, ideally we'd clean up the code around filename generation some more. Then this check could be made more robust.

r? @alexcrichton

src/librustc_codegen_llvm/back/archive.rs

@@ -9,7 +9,9 @@ use std::str;
 
 use crate::llvm::archive_ro::{ArchiveRO, Child};
 use crate::llvm::{self, ArchiveKind};
-use rustc_codegen_ssa::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION};
+use rustc_codegen_ssa::{
+    METADATA_FILENAME, RLIB_BYTECODE_EXTENSION, looks_like_rust_object_file
+};
 use rustc_codegen_ssa::back::archive::{ArchiveBuilder, find_library};
 use rustc::session::Session;
 use syntax::symbol::Symbol;
@@ -141,7 +143,7 @@ impl<'a> ArchiveBuilder<'a> for LlvmArchiveBuilder<'a> {
             }
 
             // Don't include Rust objects if LTO is enabled
-            if lto && fname.starts_with(&obj_start) && fname.ends_with(".o") {
+            if lto && looks_like_rust_object_file(fname) {
                 return true
             }
 

src/librustc_codegen_ssa/back/link.rs

@@ -3,7 +3,7 @@
 
 use rustc::session::{Session, filesearch};
 use rustc::session::config::{
-    self, RUST_CGU_EXT, DebugInfo, OutputFilenames, OutputType, PrintRequest, Sanitizer
+    self, DebugInfo, OutputFilenames, OutputType, PrintRequest, Sanitizer
 };
 use rustc::session::search_paths::PathKind;
 use rustc::middle::dependency_format::Linkage;
@@ -15,7 +15,8 @@ use rustc_fs_util::fix_windows_verbatim_for_gcc;
 use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor};
 use syntax::symbol::Symbol;
 
-use crate::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION, CrateInfo, CodegenResults};
+use crate::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION, CrateInfo,
+    looks_like_rust_object_file, CodegenResults};
 use super::archive::ArchiveBuilder;
 use super::command::Command;
 use super::linker::Linker;
@@ -1549,23 +1550,9 @@ fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
                 let canonical = f.replace("-", "_");
                 let canonical_name = name.replace("-", "_");
 
-                // Look for `.rcgu.o` at the end of the filename to conclude
-                // that this is a Rust-related object file.
-                fn looks_like_rust(s: &str) -> bool {
-                    let path = Path::new(s);
-                    let ext = path.extension().and_then(|s| s.to_str());
-                    if ext != Some(OutputType::Object.extension()) {
-                        return false
-                    }
-                    let ext2 = path.file_stem()
-                        .and_then(|s| Path::new(s).extension())
-                        .and_then(|s| s.to_str());
-                    ext2 == Some(RUST_CGU_EXT)
-                }
-
                 let is_rust_object =
                     canonical.starts_with(&canonical_name) &&
-                    looks_like_rust(&f);
+                    looks_like_rust_object_file(&f);
 
                 // If we've been requested to skip all native object files
                 // (those not generated by the rust compiler) then we can skip

src/librustc_codegen_ssa/lib.rs

@@ -22,9 +22,9 @@
 #[macro_use] extern crate rustc;
 #[macro_use] extern crate syntax;
 
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use rustc::dep_graph::WorkProduct;
-use rustc::session::config::{OutputFilenames, OutputType};
+use rustc::session::config::{OutputFilenames, OutputType, RUST_CGU_EXT};
 use rustc::middle::lang_items::LangItem;
 use rustc::hir::def_id::CrateNum;
 use rustc::ty::query::Providers;
@@ -62,6 +62,7 @@ pub struct ModuleCodegen<M> {
 pub const METADATA_FILENAME: &str = "rust.metadata.bin";
 pub const RLIB_BYTECODE_EXTENSION: &str = "bc.z";
 
+
 impl<M> ModuleCodegen<M> {
     pub fn into_compiled_module(self,
                             emit_obj: bool,
@@ -166,3 +167,22 @@ pub fn provide_extern(providers: &mut Providers<'_>) {
     crate::back::symbol_export::provide_extern(providers);
     crate::base::provide_both(providers);
 }
+
+/// Checks if the given filename ends with the `.rcgu.o` extension that `rustc`
+/// uses for the object files it generates.
+pub fn looks_like_rust_object_file(filename: &str) -> bool {
+    let path = Path::new(filename);
+    let ext = path.extension().and_then(|s| s.to_str());
+    if ext != Some(OutputType::Object.extension()) {
+        // The file name does not end with ".o", so it can't be an object file.
+        return false
+    }
+
+    // Strip the ".o" at the end
+    let ext2 = path.file_stem()
+        .and_then(|s| Path::new(s).extension())
+        .and_then(|s| s.to_str());
+
+    // Check if the "inner" extension
+    ext2 == Some(RUST_CGU_EXT)
+}

src/test/run-make-fulldeps/issue-64153/Makefile

@@ -0,0 +1,26 @@
+-include ../tools.mk
+
+# `llvm-objdump`'s output looks different on windows than on other platforms.
+# It should be enough to check on Unix platforms, so:
+# ignore-windows
+
+# Staticlibs don't include Rust object files from upstream crates if the same
+# code was already pulled into the lib via LTO. However, the bug described in
+# https://github.com/rust-lang/rust/issues/64153 lead to this exclusion not
+# working properly if the upstream crate was compiled with an explicit filename
+# (via `-o`).
+#
+# This test makes sure that functions defined in the upstream crates do not
+# appear twice in the final staticlib when listing all the symbols from it.
+
+all:
+	$(RUSTC) --crate-type rlib upstream.rs -o $(TMPDIR)/libupstream.rlib -Ccodegen-units=1
+	$(RUSTC) --crate-type staticlib downstream.rs -Clto -Ccodegen-units=1 -o $(TMPDIR)/libdownstream.a
+	# Dump all the symbols from the staticlib into `syms`
+	"$(LLVM_BIN_DIR)"/llvm-objdump -t $(TMPDIR)/libdownstream.a > $(TMPDIR)/syms
+	# Count the global instances of `issue64153_test_function`. There'll be 2
+	# if the `upstream` object file got erronously included twice.
+	# The line we are testing for with the regex looks something like:
+	# 0000000000000000 g     F .text.issue64153_test_function	00000023 issue64153_test_function
+	grep -c -e "[[:space:]]g[[:space:]]*F[[:space:]].*issue64153_test_function" $(TMPDIR)/syms > $(TMPDIR)/count
+	[ "$$(cat $(TMPDIR)/count)" -eq "1" ]

src/test/run-make-fulldeps/issue-64153/downstream.rs

@@ -0,0 +1,6 @@
+extern crate upstream;
+
+#[no_mangle]
+pub extern "C" fn foo() {
+    print!("1 + 1 = {}", upstream::issue64153_test_function(1));
+}

src/test/run-make-fulldeps/issue-64153/upstream.rs

@@ -0,0 +1,6 @@
+// Make this function extern "C", public, and no-mangle, so that it gets
+// exported from the downstream staticlib.
+#[no_mangle]
+pub extern "C" fn issue64153_test_function(x: u32) -> u32 {
+    x + 1
+}