Rollup merge of #70665 - petrochenkov:linkargs, r=nagisa

Do not lose or reorder user-provided linker arguments

Linker arguments are potentially order-dependent, so the order in which `-C link-arg` and `-C link-args` options are passed to `rustc` should be preserved when they are passed further to the linker.

Also, multiple `-C link-args` options are now appended to each other rather than overwrite each other.

In other words, `-C link-arg=a -C link-args="b c" -C link-args="d e" -C link-arg=f` is now passed as `"a" "b" "c" "d" "e" "f"` and not as `"d" "e" "a" "f"`.

Addresses https://github.com/rust-lang/rust/pull/70505#issuecomment-606780163.

2 files changed, 16 insertions, 0 deletions

diff --git a/src/test/run-make-fulldeps/link-args-order/Makefile b/src/test/run-make-fulldeps/link-args-order/Makefile
new file mode 100644
index 00000000000..98c1e0eac3b
--- /dev/null
+++ b/src/test/run-make-fulldeps/link-args-order/Makefile
@@ -0,0 +1,10 @@
+# ignore-msvc
+
+-include ../tools.mk
+
+RUSTC_FLAGS = -C linker-flavor=ld -C link-arg=a -C link-args="b c" -C link-args="d e" -C link-arg=f
+RUSTC_FLAGS_PRE = -C linker-flavor=ld -Z pre-link-arg=a -Z pre-link-args="b c" -Z pre-link-args="d e" -Z pre-link-arg=f
+
+all:
+	$(RUSTC) $(RUSTC_FLAGS) empty.rs 2>&1 | $(CGREP) '"a" "b" "c" "d" "e" "f" "g"'
+	$(RUSTC) $(RUSTC_FLAGS_PRE) empty.rs 2>&1 | $(CGREP) '"a" "b" "c" "d" "e" "f"'
diff --git a/src/test/run-make-fulldeps/link-args-order/empty.rs b/src/test/run-make-fulldeps/link-args-order/empty.rs
new file mode 100644
index 00000000000..2439171004b
--- /dev/null
+++ b/src/test/run-make-fulldeps/link-args-order/empty.rs
@@ -0,0 +1,6 @@
+#![feature(link_args)]
+
+#[link_args = "g"]
+extern "C" {}
+
+fn main() {}