Add test of --print KIND=PATH

Author: dtolnay

tests/run-make/print-cfg/Makefile

@@ -2,7 +2,7 @@
 
 include ../tools.mk
 
-all: default
+all: default output_to_file
 	$(RUSTC) --target x86_64-pc-windows-gnu --print cfg | $(CGREP) windows
 	$(RUSTC) --target x86_64-pc-windows-gnu --print cfg | $(CGREP) x86_64
 	$(RUSTC) --target i686-pc-windows-msvc --print cfg | $(CGREP) msvc
@@ -11,6 +11,23 @@ all: default
 	$(RUSTC) --target arm-unknown-linux-gnueabihf --print cfg | $(CGREP) target_abi=
 	$(RUSTC) --target arm-unknown-linux-gnueabihf --print cfg | $(CGREP) eabihf
 
+output_to_file:
+	# Backend-independent, printed by rustc_driver_impl/src/lib.rs
+	$(RUSTC) --target x86_64-pc-windows-gnu --print cfg=$(TMPDIR)/cfg.txt
+	$(CGREP) windows < $(TMPDIR)/cfg.txt
+
+	# Printed from CodegenBackend trait impl in rustc_codegen_llvm/src/lib.rs
+	$(RUSTC) --print relocation-models=$(TMPDIR)/relocation-models.txt
+	$(CGREP) dynamic-no-pic < $(TMPDIR)/relocation-models.txt
+
+	# Printed by compiler/rustc_codegen_llvm/src/llvm_util.rs
+	$(RUSTC) --target wasm32-unknown-unknown --print target-features=$(TMPDIR)/target-features.txt
+	$(CGREP) reference-types < $(TMPDIR)/target-features.txt
+
+	# Printed by C++ code in rustc_llvm/llvm-wrapper/PassWrapper.cpp
+	$(RUSTC) --target x86_64-pc-windows-gnu --print target-cpus=$(TMPDIR)/target-cpus.txt
+	$(CGREP) native < $(TMPDIR)/target-cpus.txt
+
 ifdef IS_WINDOWS
 default:
 	$(RUSTC) --print cfg | $(CGREP) windows