Rollup merge of #89025 - ricobbe:raw-dylib-link-ordinal, r=michaelwoerister

Implement `#[link_ordinal(n)]`

Allows the use of `#[link_ordinal(n)]` with `#[link(kind = "raw-dylib")]`, allowing Rust to link against DLLs that export symbols by ordinal rather than by name.  As long as the ordinal matches, the name of the function in Rust is not required to match the name of the corresponding function in the exporting DLL.

Part of #58713.

20 files changed, 201 insertions, 23 deletions

diff --git a/compiler/rustc_codegen_llvm/src/back/archive.rs b/compiler/rustc_codegen_llvm/src/back/archive.rs
index ebc3b704158..2fb5a0f9faf 100644
--- a/compiler/rustc_codegen_llvm/src/back/archive.rs
+++ b/compiler/rustc_codegen_llvm/src/back/archive.rs
@@ -163,13 +163,13 @@ impl<'a> ArchiveBuilder<'a> for LlvmArchiveBuilder<'a> {
         // All import names are Rust identifiers and therefore cannot contain \0 characters.
         // FIXME: when support for #[link_name] implemented, ensure that import.name values don't
         // have any \0 characters
-        let import_name_vector: Vec<CString> = dll_imports
+        let import_name_and_ordinal_vector: Vec<(CString, Option<u16>)> = dll_imports
             .iter()
             .map(|import: &DllImport| {
                 if self.config.sess.target.arch == "x86" {
-                    LlvmArchiveBuilder::i686_decorated_name(import)
+                    (LlvmArchiveBuilder::i686_decorated_name(import), import.ordinal)
                 } else {
-                    CString::new(import.name.to_string()).unwrap()
+                    (CString::new(import.name.to_string()).unwrap(), import.ordinal)
                 }
             })
             .collect();
@@ -184,9 +184,9 @@ impl<'a> ArchiveBuilder<'a> for LlvmArchiveBuilder<'a> {
             dll_imports.iter().map(|import| import.name.to_string()).collect::<Vec<_>>().join(", "),
         );
 
-        let ffi_exports: Vec<LLVMRustCOFFShortExport> = import_name_vector
+        let ffi_exports: Vec<LLVMRustCOFFShortExport> = import_name_and_ordinal_vector
             .iter()
-            .map(|name_z| LLVMRustCOFFShortExport::from_name(name_z.as_ptr()))
+            .map(|(name_z, ordinal)| LLVMRustCOFFShortExport::new(name_z.as_ptr(), *ordinal))
             .collect();
         let result = unsafe {
             crate::llvm::LLVMRustWriteImportLibrary(
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 5d437b2a068..63eca00de2a 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -34,11 +34,18 @@ pub enum LLVMRustResult {
 #[repr(C)]
 pub struct LLVMRustCOFFShortExport {
     pub name: *const c_char,
+    pub ordinal_present: bool,
+    // value of `ordinal` only important when `ordinal_present` is true
+    pub ordinal: u16,
 }
 
 impl LLVMRustCOFFShortExport {
-    pub fn from_name(name: *const c_char) -> LLVMRustCOFFShortExport {
-        LLVMRustCOFFShortExport { name }
+    pub fn new(name: *const c_char, ordinal: Option<u16>) -> LLVMRustCOFFShortExport {
+        LLVMRustCOFFShortExport {
+            name,
+            ordinal_present: ordinal.is_some(),
+            ordinal: ordinal.unwrap_or(0),
+        }
     }
 }
 
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 97114729c0a..b7b0524e2a3 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -1753,10 +1753,11 @@ LLVMRustBuildMaxNum(LLVMBuilderRef B, LLVMValueRef LHS, LLVMValueRef RHS) {
 }
 
 // This struct contains all necessary info about a symbol exported from a DLL.
-// At the moment, it's just the symbol's name, but we use a separate struct to
-// make it easier to add other information like ordinal later.
 struct LLVMRustCOFFShortExport {
   const char* name;
+  bool ordinal_present;
+  // The value of `ordinal` is only meaningful if `ordinal_present` is true.
+  uint16_t ordinal;
 };
 
 // Machine must be a COFF machine type, as defined in PE specs.
@@ -1772,13 +1773,15 @@ extern "C" LLVMRustResult LLVMRustWriteImportLibrary(
   ConvertedExports.reserve(NumExports);
 
   for (size_t i = 0; i < NumExports; ++i) {
+    bool ordinal_present = Exports[i].ordinal_present;
+    uint16_t ordinal = ordinal_present ? Exports[i].ordinal : 0;
     ConvertedExports.push_back(llvm::object::COFFShortExport{
       Exports[i].name,  // Name
       std::string{},    // ExtName
       std::string{},    // SymbolName
       std::string{},    // AliasTarget
-      0,                // Ordinal
-      false,            // Noname
+      ordinal,          // Ordinal
+      ordinal_present,  // Noname
       false,            // Data
       false,            // Private
       false             // Constant
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 75b9e2ef62a..a7446765900 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -433,6 +433,12 @@ impl Collector<'tcx> {
                 }
             }
         };
-        DllImport { name: item.ident.name, ordinal: None, calling_convention, span: item.span }
+
+        DllImport {
+            name: item.ident.name,
+            ordinal: self.tcx.codegen_fn_attrs(item.id.def_id).link_ordinal,
+            calling_convention,
+            span: item.span,
+        }
     }
 }
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index b2705c76939..b054d21adaa 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -22,7 +22,7 @@ pub struct CodegenFnAttrs {
     /// imported function has in the dynamic library. Note that this must not
     /// be set when `link_name` is set. This is for foreign items with the
     /// "raw-dylib" kind.
-    pub link_ordinal: Option<usize>,
+    pub link_ordinal: Option<u16>,
     /// The `#[target_feature(enable = "...")]` attribute and the enabled
     /// features (only enabled features are supported right now).
     pub target_features: Vec<Symbol>,
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index f21c5c760ea..df7f2aea9c3 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -2861,6 +2861,14 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
         } else if attr.has_name(sym::link_name) {
             codegen_fn_attrs.link_name = attr.value_str();
         } else if attr.has_name(sym::link_ordinal) {
+            if link_ordinal_span.is_some() {
+                tcx.sess
+                    .struct_span_err(
+                        attr.span,
+                        "multiple `link_ordinal` attributes on a single definition",
+                    )
+                    .emit();
+            }
             link_ordinal_span = Some(attr.span);
             if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
                 codegen_fn_attrs.link_ordinal = ordinal;
@@ -3156,22 +3164,41 @@ fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
     false
 }
 
-fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
+fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
     use rustc_ast::{Lit, LitIntType, LitKind};
     let meta_item_list = attr.meta_item_list();
     let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
     let sole_meta_list = match meta_item_list {
         Some([item]) => item.literal(),
+        Some(_) => {
+            tcx.sess
+                .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
+                .note("the attribute requires exactly one argument")
+                .emit();
+            return None;
+        }
         _ => None,
     };
     if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
-        if *ordinal <= usize::MAX as u128 {
-            Some(*ordinal as usize)
+        // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
+        // the ordinal must fit into 16 bits.  Similarly, the Ordinal field in COFFShortExport (defined
+        // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
+        // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
+        //
+        // FIXME: should we allow an ordinal of 0?  The MSVC toolchain has inconsistent support for this:
+        // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
+        // a zero ordinal.  However, llvm-dlltool is perfectly happy to generate an import library
+        // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
+        // library produced by LLVM with an ordinal of 0, and it generates an .EXE.  (I don't know yet
+        // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
+        // about LINK.EXE failing.)
+        if *ordinal <= u16::MAX as u128 {
+            Some(*ordinal as u16)
         } else {
             let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
             tcx.sess
                 .struct_span_err(attr.span, &msg)
-                .note("the value may not exceed `usize::MAX`")
+                .note("the value may not exceed `u16::MAX`")
                 .emit();
             None
         }
diff --git a/src/test/run-make/raw-dylib-link-ordinal/Makefile b/src/test/run-make/raw-dylib-link-ordinal/Makefile
new file mode 100644
index 00000000000..04b257d0632
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/Makefile
@@ -0,0 +1,18 @@
+# Test the behavior of #[link(.., kind = "raw-dylib")] and #[link_ordinal] on windows-msvc
+
+# only-windows-msvc
+
+-include ../../run-make-fulldeps/tools.mk
+
+all:
+	$(call COMPILE_OBJ,"$(TMPDIR)"/exporter.obj,exporter.c)
+	$(CC) "$(TMPDIR)"/exporter.obj exporter.def -link -dll -out:"$(TMPDIR)"/exporter.dll
+	$(RUSTC) --crate-type lib --crate-name raw_dylib_test lib.rs
+	$(RUSTC) --crate-type bin driver.rs -L "$(TMPDIR)"
+	"$(TMPDIR)"/driver > "$(TMPDIR)"/output.txt
+
+ifdef RUSTC_BLESS_TEST
+	cp "$(TMPDIR)"/output.txt output.txt
+else
+	$(DIFF) output.txt "$(TMPDIR)"/output.txt
+endif
diff --git a/src/test/run-make/raw-dylib-link-ordinal/driver.rs b/src/test/run-make/raw-dylib-link-ordinal/driver.rs
new file mode 100644
index 00000000000..4059ede11fc
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/driver.rs
@@ -0,0 +1,5 @@
+extern crate raw_dylib_test;
+
+fn main() {
+    raw_dylib_test::library_function();
+}
diff --git a/src/test/run-make/raw-dylib-link-ordinal/exporter.c b/src/test/run-make/raw-dylib-link-ordinal/exporter.c
new file mode 100644
index 00000000000..a9dd6da6616
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/exporter.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void exported_function() {
+    printf("exported_function\n");
+}
diff --git a/src/test/run-make/raw-dylib-link-ordinal/exporter.def b/src/test/run-make/raw-dylib-link-ordinal/exporter.def
new file mode 100644
index 00000000000..1a4b4c941b6
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/exporter.def
@@ -0,0 +1,3 @@
+LIBRARY exporter
+EXPORTS
+    exported_function @13 NONAME
diff --git a/src/test/run-make/raw-dylib-link-ordinal/lib.rs b/src/test/run-make/raw-dylib-link-ordinal/lib.rs
new file mode 100644
index 00000000000..20609caa5be
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/lib.rs
@@ -0,0 +1,13 @@
+#![feature(raw_dylib)]
+
+#[link(name = "exporter", kind = "raw-dylib")]
+extern {
+    #[link_ordinal(13)]
+    fn imported_function();
+}
+
+pub fn library_function() {
+    unsafe {
+        imported_function();
+    }
+}
diff --git a/src/test/run-make/raw-dylib-link-ordinal/output.txt b/src/test/run-make/raw-dylib-link-ordinal/output.txt
new file mode 100644
index 00000000000..2d0ed60f216
--- /dev/null
+++ b/src/test/run-make/raw-dylib-link-ordinal/output.txt
@@ -0,0 +1 @@
+exported_function
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.rs b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.rs
new file mode 100644
index 00000000000..c391ccd1c82
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.rs
@@ -0,0 +1,11 @@
+#![feature(raw_dylib)]
+//~^ WARN the feature `raw_dylib` is incomplete
+
+#[link(name = "foo")]
+extern "C" {
+    #[link_ordinal()]
+    //~^ ERROR incorrect number of arguments to `#[link_ordinal]`
+    fn foo();
+}
+
+fn main() {}
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.stderr b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.stderr
new file mode 100644
index 00000000000..8e9edfb9d20
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-missing-argument.stderr
@@ -0,0 +1,19 @@
+warning: the feature `raw_dylib` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/link-ordinal-missing-argument.rs:1:12
+   |
+LL | #![feature(raw_dylib)]
+   |            ^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+
+error: incorrect number of arguments to `#[link_ordinal]`
+  --> $DIR/link-ordinal-missing-argument.rs:6:5
+   |
+LL |     #[link_ordinal()]
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: the attribute requires exactly one argument
+
+error: aborting due to previous error; 1 warning emitted
+
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.rs b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.rs
new file mode 100644
index 00000000000..98741212677
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.rs
@@ -0,0 +1,13 @@
+// only-windows-msvc
+#![feature(raw_dylib)]
+//~^ WARN the feature `raw_dylib` is incomplete
+
+#[link(name = "foo", kind = "raw-dylib")]
+extern "C" {
+    #[link_ordinal(1)]
+    #[link_ordinal(2)]
+    //~^ ERROR multiple `link_ordinal` attributes on a single definition
+    fn foo();
+}
+
+fn main() {}
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.stderr b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.stderr
new file mode 100644
index 00000000000..a79fb2de944
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.stderr
@@ -0,0 +1,17 @@
+warning: the feature `raw_dylib` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/link-ordinal-multiple.rs:2:12
+   |
+LL | #![feature(raw_dylib)]
+   |            ^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+
+error: multiple `link_ordinal` attributes on a single definition
+  --> $DIR/link-ordinal-multiple.rs:8:5
+   |
+LL |     #[link_ordinal(2)]
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error; 1 warning emitted
+
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.rs b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.rs
index 10db4972970..b6089d27e7a 100644
--- a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.rs
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.rs
@@ -3,8 +3,8 @@
 
 #[link(name = "foo")]
 extern "C" {
-    #[link_ordinal(18446744073709551616)]
-    //~^ ERROR ordinal value in `link_ordinal` is too large: `18446744073709551616`
+    #[link_ordinal(72436)]
+    //~^ ERROR ordinal value in `link_ordinal` is too large: `72436`
     fn foo();
 }
 
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.stderr b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.stderr
index 35f9b53fdf7..bbe985fa10a 100644
--- a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.stderr
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-large.stderr
@@ -7,13 +7,13 @@ LL | #![feature(raw_dylib)]
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
 
-error: ordinal value in `link_ordinal` is too large: `18446744073709551616`
+error: ordinal value in `link_ordinal` is too large: `72436`
   --> $DIR/link-ordinal-too-large.rs:6:5
    |
-LL |     #[link_ordinal(18446744073709551616)]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     #[link_ordinal(72436)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: the value may not exceed `usize::MAX`
+   = note: the value may not exceed `u16::MAX`
 
 error: aborting due to previous error; 1 warning emitted
 
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.rs b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.rs
new file mode 100644
index 00000000000..93286c616c5
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.rs
@@ -0,0 +1,11 @@
+#![feature(raw_dylib)]
+//~^ WARN the feature `raw_dylib` is incomplete
+
+#[link(name = "foo")]
+extern "C" {
+    #[link_ordinal(3, 4)]
+    //~^ ERROR incorrect number of arguments to `#[link_ordinal]`
+    fn foo();
+}
+
+fn main() {}
diff --git a/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.stderr b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.stderr
new file mode 100644
index 00000000000..484c85a0f42
--- /dev/null
+++ b/src/test/ui/rfc-2627-raw-dylib/link-ordinal-too-many-arguments.stderr
@@ -0,0 +1,19 @@
+warning: the feature `raw_dylib` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/link-ordinal-too-many-arguments.rs:1:12
+   |
+LL | #![feature(raw_dylib)]
+   |            ^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+
+error: incorrect number of arguments to `#[link_ordinal]`
+  --> $DIR/link-ordinal-too-many-arguments.rs:6:5
+   |
+LL |     #[link_ordinal(3, 4)]
+   |     ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the attribute requires exactly one argument
+
+error: aborting due to previous error; 1 warning emitted
+