Require static native libraries when linking static executables

gcc/ld will create a dynamically-linked executable without warning, even
when passed `-static`, when asked to link to a `.so`. Avoid this
confusing and unintended behavior by always using the static version of
libraries when trying to link static executables.

Fixes rust-lang#54243

Author: smaeul

src/librustc_codegen_llvm/back/link.rs

@@ -1414,8 +1414,8 @@ fn add_upstream_rust_crates(cmd: &mut dyn Linker,
     }
 }
 
-// Link in all of our upstream crates' native dependencies. Remember that
-// all of these upstream native dependencies are all non-static
+// Link in all of our upstream crates' native dependencies. Remember that when
+// linking libraries, these upstream native dependencies are all non-static
 // dependencies. We've got two cases then:
 //
 // 1. The upstream crate is an rlib. In this case we *must* link in the
@@ -1459,7 +1459,14 @@ fn add_upstream_native_libraries(cmd: &mut dyn Linker,
                 continue
             }
             match lib.kind {
-                NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
+                NativeLibraryKind::NativeUnknown => {
+                    // When creating executables, match library linkage to that of the executable.
+                    if crate_type == config::CrateType::Executable && sess.crt_static() {
+                        cmd.link_staticlib(&name.as_str())
+                    } else {
+                        cmd.link_dylib(&name.as_str())
+                    }
+                },
                 NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
                 NativeLibraryKind::NativeStaticNobundle => {
                     // Link "static-nobundle" native libs only if the crate they originate from