From 09e1fae118bce2530ef34e50f666b46cc2070e41 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Wed, 28 Dec 2022 17:10:21 +0000
Subject: [PATCH] Support linking to rust dylibs from a staticlib

---
 .../rustc_metadata/src/dependency_format.rs   | 23 +++++++---------
 .../run-make/staticlib-dylib-linkage/Makefile | 27 +++++++++++++++++++
 tests/run-make/staticlib-dylib-linkage/bar.rs |  5 ++++
 tests/run-make/staticlib-dylib-linkage/foo.c  | 10 +++++++
 tests/run-make/staticlib-dylib-linkage/foo.rs | 13 +++++++++
 5 files changed, 65 insertions(+), 13 deletions(-)
 create mode 100644 tests/run-make/staticlib-dylib-linkage/Makefile
 create mode 100644 tests/run-make/staticlib-dylib-linkage/bar.rs
 create mode 100644 tests/run-make/staticlib-dylib-linkage/foo.c
 create mode 100644 tests/run-make/staticlib-dylib-linkage/foo.rs

diff --git a/compiler/rustc_metadata/src/dependency_format.rs b/compiler/rustc_metadata/src/dependency_format.rs
index 39ef4276faf..590a7374d11 100644
--- a/compiler/rustc_metadata/src/dependency_format.rs
+++ b/compiler/rustc_metadata/src/dependency_format.rs
@@ -89,11 +89,12 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
         // to try to eagerly statically link all dependencies. This is normally
         // done for end-product dylibs, not intermediate products.
         //
-        // Treat cdylibs similarly. If `-C prefer-dynamic` is set, the caller may
-        // be code-size conscious, but without it, it makes sense to statically
-        // link a cdylib.
-        CrateType::Dylib | CrateType::Cdylib if !sess.opts.cg.prefer_dynamic => Linkage::Static,
-        CrateType::Dylib | CrateType::Cdylib => Linkage::Dynamic,
+        // Treat cdylibs and staticlibs similarly. If `-C prefer-dynamic` is set,
+        // the caller may be code-size conscious, but without it, it makes sense
+        // to statically link a cdylib or staticlib.
+        CrateType::Dylib | CrateType::Cdylib | CrateType::Staticlib => {
+            if sess.opts.cg.prefer_dynamic { Linkage::Dynamic } else { Linkage::Static }
+        }
 
         // If the global prefer_dynamic switch is turned off, or the final
         // executable will be statically linked, prefer static crate linkage.
@@ -108,9 +109,6 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
         // No linkage happens with rlibs, we just needed the metadata (which we
         // got long ago), so don't bother with anything.
         CrateType::Rlib => Linkage::NotLinked,
-
-        // staticlibs must have all static dependencies.
-        CrateType::Staticlib => Linkage::Static,
     };
 
     match preferred_linkage {
@@ -123,12 +121,11 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
                 return v;
             }
 
-            // Staticlibs and static executables must have all static dependencies.
+            // Static executables must have all static dependencies.
             // If any are not found, generate some nice pretty errors.
-            if ty == CrateType::Staticlib
-                || (ty == CrateType::Executable
-                    && sess.crt_static(Some(ty))
-                    && !sess.target.crt_static_allows_dylibs)
+            if ty == CrateType::Executable
+                && sess.crt_static(Some(ty))
+                && !sess.target.crt_static_allows_dylibs
             {
                 for &cnum in tcx.crates(()).iter() {
                     if tcx.dep_kind(cnum).macros_only() {
diff --git a/tests/run-make/staticlib-dylib-linkage/Makefile b/tests/run-make/staticlib-dylib-linkage/Makefile
new file mode 100644
index 00000000000..bf811395981
--- /dev/null
+++ b/tests/run-make/staticlib-dylib-linkage/Makefile
@@ -0,0 +1,27 @@
+include ../tools.mk
+
+TARGET_SYSROOT := $(shell $(RUSTC) --print sysroot)/lib/rustlib/$(TARGET)/lib
+
+ifdef IS_MSVC
+LIBSTD := $(wildcard $(TARGET_SYSROOT)/libstd-*.dll.lib)
+else
+LIBSTD := $(wildcard $(TARGET_SYSROOT)/$(call DYLIB_GLOB,std))
+STD := $(basename $(patsubst lib%,%, $(notdir $(LIBSTD))))
+endif
+
+all: $(call RUN_BINFILE,foo)
+	$(call RUN,foo)
+
+ifdef IS_MSVC
+CLIBS := $(TMPDIR)/foo.lib $(TMPDIR)/bar.dll.lib $(LIBSTD)
+$(call RUN_BINFILE,foo): $(call STATICLIB,foo)
+	$(CC) $(CFLAGS) foo.c $(CLIBS) $(call OUT_EXE,foo)
+else
+CLIBS := $(TMPDIR)/libfoo.a -lbar -l$(STD) -L $(TMPDIR) -L $(TARGET_SYSROOT)
+$(call RUN_BINFILE,foo): $(call STATICLIB,foo)
+	$(CC) $(CFLAGS) foo.c $(CLIBS) -o $(call RUN_BINFILE,foo)
+endif
+
+$(call STATICLIB,foo):
+	$(RUSTC) -C prefer-dynamic bar.rs
+	$(RUSTC) foo.rs
diff --git a/tests/run-make/staticlib-dylib-linkage/bar.rs b/tests/run-make/staticlib-dylib-linkage/bar.rs
new file mode 100644
index 00000000000..b3a7539abae
--- /dev/null
+++ b/tests/run-make/staticlib-dylib-linkage/bar.rs
@@ -0,0 +1,5 @@
+#![crate_type = "dylib"]
+
+pub fn bar() {
+    println!("hello!");
+}
diff --git a/tests/run-make/staticlib-dylib-linkage/foo.c b/tests/run-make/staticlib-dylib-linkage/foo.c
new file mode 100644
index 00000000000..154f9682ef8
--- /dev/null
+++ b/tests/run-make/staticlib-dylib-linkage/foo.c
@@ -0,0 +1,10 @@
+#include <assert.h>
+
+extern void foo();
+extern unsigned bar(unsigned a, unsigned b);
+
+int main() {
+  foo();
+  assert(bar(1, 2) == 3);
+  return 0;
+}
diff --git a/tests/run-make/staticlib-dylib-linkage/foo.rs b/tests/run-make/staticlib-dylib-linkage/foo.rs
new file mode 100644
index 00000000000..af439391c75
--- /dev/null
+++ b/tests/run-make/staticlib-dylib-linkage/foo.rs
@@ -0,0 +1,13 @@
+#![crate_type = "staticlib"]
+
+extern crate bar;
+
+#[no_mangle]
+pub extern "C" fn foo() {
+    bar::bar();
+}
+
+#[no_mangle]
+pub extern "C" fn bar(a: u32, b: u32) -> u32 {
+    a + b
+}