Move -Z lto to -C lto.

Closes #12443

src/librustc/driver/config.rs

@@ -180,7 +180,6 @@ debugging_opts!(
         GC,
         PRINT_LINK_ARGS,
         PRINT_LLVM_PASSES,
-        LTO,
         AST_JSON,
         AST_JSON_NOEXPAND,
         LS,
@@ -219,7 +218,6 @@ pub fn debugging_opts_map() -> Vec<(&'static str, &'static str, u64)> {
      ("print-llvm-passes",
       "Prints the llvm optimization passes being run",
       PRINT_LLVM_PASSES),
-     ("lto", "Perform LLVM link-time optimizations", LTO),
      ("ast-json", "Print the AST as JSON and halt", AST_JSON),
      ("ast-json-noexpand", "Print the pre-expansion AST as JSON and halt", AST_JSON_NOEXPAND),
      ("ls", "List the symbols defined by a library crate", LS),
@@ -353,6 +351,8 @@ cgoptions!(
         "system linker to link outputs with"),
     link_args: Vec<String> = (Vec::new(), parse_list,
         "extra arguments to pass to the linker (space separated)"),
+    lto: bool = (false, parse_bool,
+        "perform LLVM link-time optimizations"),
     target_cpu: String = ("generic".to_string(), parse_string,
         "select target processor (llc -mcpu=help for details)"),
     target_feature: String = ("".to_string(), parse_string,

src/librustc/driver/session.rs

@@ -168,7 +168,7 @@ impl Session {
         self.debugging_opt(config::PRINT_LLVM_PASSES)
     }
     pub fn lto(&self) -> bool {
-        self.debugging_opt(config::LTO)
+        self.opts.cg.lto
     }
     pub fn no_landing_pads(&self) -> bool {
         self.debugging_opt(config::NO_LANDING_PADS)

src/test/compile-fail/issue-11154.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z lto -C prefer-dynamic
+// compile-flags: -C lto -C prefer-dynamic
 
 // error-pattern: cannot prefer dynamic linking
 

src/test/debuginfo/cross-crate-type-uniquing.rs

@@ -14,7 +14,7 @@
 extern crate cross_crate_debuginfo_type_uniquing;
 
 // no-prefer-dynamic
-// compile-flags:-g -Zlto
+// compile-flags:-g -C lto
 
 pub struct C;
 pub fn p() -> C {

src/test/run-make/issue-14500/Makefile

@@ -8,7 +8,7 @@
 
 all:
 	$(RUSTC) foo.rs --crate-type=rlib
-	$(RUSTC) bar.rs --crate-type=staticlib -Zlto -L. -o $(TMPDIR)/libbar.a
+	$(RUSTC) bar.rs --crate-type=staticlib -C lto -L. -o $(TMPDIR)/libbar.a
 	$(CC) foo.c -lbar -o $(call RUN_BINFILE,foo) $(EXTRACFLAGS)
 	$(call RUN,foo)
 

src/test/run-make/lto-smoke-c/Makefile

@@ -4,6 +4,6 @@
 CC := $(CC:-g=)
 
 all:
-	$(RUSTC) foo.rs -Z lto
+	$(RUSTC) foo.rs -C lto
 	$(CC) bar.c -lfoo -o $(call RUN_BINFILE,bar) $(EXTRACFLAGS) -lstdc++
 	$(call RUN,bar)

src/test/run-make/lto-smoke/Makefile

@@ -2,5 +2,5 @@
 
 all:
 	$(RUSTC) lib.rs
-	$(RUSTC) main.rs -Z lto
+	$(RUSTC) main.rs -C lto
 	$(call RUN,main)

src/test/run-make/lto-syntax-extension/Makefile

@@ -14,5 +14,5 @@ all: $(DOTEST)
 dotest:
 	env
 	$(RUSTC) lib.rs
-	$(RUSTC) main.rs -Z lto
+	$(RUSTC) main.rs -C lto
 	$(call RUN,main)

src/test/run-pass/sepcomp-lib-lto.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Check that we can use `-Z lto` when linking against libraries that were
+// Check that we can use `-C lto` when linking against libraries that were
 // separately compiled.
 
 // aux-build:sepcomp_lib.rs
-// compile-flags: -Z lto
+// compile-flags: -C lto
 // no-prefer-dynamic
 
 extern crate sepcomp_lib;