rustc: More stable hashes of command line arguments

Currently rustc isn't always the best at producing deterministic builds of a
crate when the source directory of a crate is changed. This is happening due to
what appears two different sources:

* First the `-L` paths passed to rustc are hashed into the crate hash. These
  paths through Cargo are typically absolute paths that can vary if the build
  directory changes.

* Next the paths passed to `--extern` are also hashed which like `-L` can change
  if the build directory changes.

This commit fixes these two sources of nondeterminism by ensuring that avoiding
tracking the hashes of these arguments on the command line. For `-L` paths
they're either related to loading crates (whose hashes are tracked elsewhere) or
native librarise used in the linking phase (which isn't incremental). The
`--extern` paths are similar in that they're related to crate resolution which
is already tracked independently of the command line arguments.

Closes #48019

2 files changed, 68 insertions, 10 deletions

diff --git a/src/test/run-make/reproducible-build/Makefile b/src/test/run-make/reproducible-build/Makefile
index 8e799ca1a43..629e6185051 100644
--- a/src/test/run-make/reproducible-build/Makefile
+++ b/src/test/run-make/reproducible-build/Makefile
@@ -1,20 +1,78 @@
 -include ../tools.mk
-all:
+all:  \
+	smoke \
+	debug \
+	opt \
+	link_paths \
+	remap_paths \
+	different_source_dirs \
+	extern_flags
+
+smoke:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
 	$(RUSTC) reproducible-build-aux.rs
 	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build1"
 	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build2"
+	$(B2)
 	nm "$(TMPDIR)/reproducible-build1" | sort > "$(TMPDIR)/reproducible-build1.nm"
 	nm "$(TMPDIR)/reproducible-build2" | sort > "$(TMPDIR)/reproducible-build2.nm"
 	cmp "$(TMPDIR)/reproducible-build1.nm" "$(TMPDIR)/reproducible-build2.nm" || exit 1
+
+debug:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
 	$(RUSTC) reproducible-build-aux.rs -g
-	$(RUSTC) reproducible-build.rs -g -o"$(TMPDIR)/reproducible-build1-debug"
-	$(RUSTC) reproducible-build.rs -g -o"$(TMPDIR)/reproducible-build2-debug"
-	nm "$(TMPDIR)/reproducible-build1-debug" | sort > "$(TMPDIR)/reproducible-build1-debug.nm"
-	nm "$(TMPDIR)/reproducible-build2-debug" | sort > "$(TMPDIR)/reproducible-build2-debug.nm"
+	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build1" -g
+	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build2" -g
+	nm "$(TMPDIR)/reproducible-build1" | sort > "$(TMPDIR)/reproducible-build1-debug.nm"
+	nm "$(TMPDIR)/reproducible-build2" | sort > "$(TMPDIR)/reproducible-build2-debug.nm"
 	cmp "$(TMPDIR)/reproducible-build1-debug.nm" "$(TMPDIR)/reproducible-build2-debug.nm" || exit 1
+
+opt:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
 	$(RUSTC) reproducible-build-aux.rs -O
-	$(RUSTC) reproducible-build.rs -O -o"$(TMPDIR)/reproducible-build1-opt"
-	$(RUSTC) reproducible-build.rs -O -o"$(TMPDIR)/reproducible-build2-opt"
-	nm "$(TMPDIR)/reproducible-build1-opt" | sort > "$(TMPDIR)/reproducible-build1-opt.nm"
-	nm "$(TMPDIR)/reproducible-build2-opt" | sort > "$(TMPDIR)/reproducible-build2-opt.nm"
+	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build1" -O
+	$(RUSTC) reproducible-build.rs -o"$(TMPDIR)/reproducible-build2" -O
+	nm "$(TMPDIR)/reproducible-build1" | sort > "$(TMPDIR)/reproducible-build1-opt.nm"
+	nm "$(TMPDIR)/reproducible-build2" | sort > "$(TMPDIR)/reproducible-build2-opt.nm"
 	cmp "$(TMPDIR)/reproducible-build1-opt.nm" "$(TMPDIR)/reproducible-build2-opt.nm" || exit 1
+
+link_paths:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
+	$(RUSTC) reproducible-build-aux.rs
+	$(RUSTC) reproducible-build.rs --crate-type rlib -L /b
+	cp $(TMPDIR)/libreproducible_build.rlib $(TMPDIR)/libfoo.rlib
+	$(RUSTC) reproducible-build.rs --crate-type rlib -L /a
+	cmp "$(TMPDIR)/libreproducible_build.rlib" "$(TMPDIR)/libfoo.rlib" || exit 1
+
+remap_paths:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
+	$(RUSTC) reproducible-build-aux.rs
+	$(RUSTC) reproducible-build.rs --crate-type rlib --remap-path-prefix=/a=/c
+	cp $(TMPDIR)/libreproducible_build.rlib $(TMPDIR)/libfoo.rlib
+	$(RUSTC) reproducible-build.rs --crate-type rlib --remap-path-prefix=/b=/c
+	cmp "$(TMPDIR)/libreproducible_build.rlib" "$(TMPDIR)/libfoo.rlib" || exit 1
+
+different_source_dirs:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
+	$(RUSTC) reproducible-build-aux.rs
+	mkdir $(TMPDIR)/test
+	cp reproducible-build.rs $(TMPDIR)/test
+	$(RUSTC) reproducible-build.rs --crate-type rlib --remap-path-prefix=$$PWD=/b
+	cp $(TMPDIR)/libreproducible_build.rlib $(TMPDIR)/libfoo.rlib
+	(cd $(TMPDIR)/test && $(RUSTC) reproducible-build.rs \
+		--remap-path-prefix=$(TMPDIR)/test=/b \
+		--crate-type rlib)
+	cmp "$(TMPDIR)/libreproducible_build.rlib" "$(TMPDIR)/libfoo.rlib" || exit 1
+
+extern_flags:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
+	$(RUSTC) reproducible-build-aux.rs
+	$(RUSTC) reproducible-build.rs \
+		--extern reproducible_build_aux=$(TMPDIR)/libreproducible_build_aux.rlib \
+		--crate-type rlib
+	cp $(TMPDIR)/libreproducible_build_aux.rlib $(TMPDIR)/libbar.rlib
+	cp $(TMPDIR)/libreproducible_build.rlib $(TMPDIR)/libfoo.rlib
+	$(RUSTC) reproducible-build.rs \
+		--extern reproducible_build_aux=$(TMPDIR)/libbar.rlib \
+		--crate-type rlib
+	cmp "$(TMPDIR)/libreproducible_build.rlib" "$(TMPDIR)/libfoo.rlib" || exit 1
diff --git a/src/test/run-make/reproducible-build/reproducible-build.rs b/src/test/run-make/reproducible-build/reproducible-build.rs
index b47d780e529..a040c0f858d 100644
--- a/src/test/run-make/reproducible-build/reproducible-build.rs
+++ b/src/test/run-make/reproducible-build/reproducible-build.rs
@@ -28,7 +28,7 @@
 // - Trait object shims
 // - Fn Pointer shims
 
-#![allow(dead_code)]
+#![allow(dead_code, warnings)]
 
 extern crate reproducible_build_aux;