Update to Rust 2018 edition (#632)

* initial cargo fix run

* Upgrade cranelift-entity crate

* Upgrade bforest crate

* Upgrade the codegen crate

* Upgrade the faerie crate

* Upgrade the filetests crate

* Upgrade the codegen-meta crate

* Upgrade the frontend crate

* Upgrade the cranelift-module crate

* Upgrade the cranelift-native crate

* Upgrade the cranelift-preopt crate

* Upgrade the cranelift-reader crate

* Upgrade the cranelift-serde crate

* Upgrade the cranelift-simplejit crate

* Upgrade the cranelift or cranelift-umbrella crate

* Upgrade the cranelift-wasm crate

* Upgrade cranelift-tools crate

* Use new import style on remaining files

* run format-all.sh

* run test-all.sh, update Readme and travis ci configuration
fixed an AssertionError also

* Remove deprecated functions

lib/frontend/src/frontend.rs

@@ -1,4 +1,6 @@
 //! A frontend for building Cranelift IR from other languages.
+use crate::ssa::{Block, SSABuilder, SideEffects};
+use crate::variable::Variable;
 use cranelift_codegen::cursor::{Cursor, FuncCursor};
 use cranelift_codegen::entity::{EntitySet, SecondaryMap};
 use cranelift_codegen::ir;
@@ -11,9 +13,7 @@ use cranelift_codegen::ir::{
 };
 use cranelift_codegen::isa::{TargetFrontendConfig, TargetIsa};
 use cranelift_codegen::packed_option::PackedOption;
-use ssa::{Block, SSABuilder, SideEffects};
 use std::vec::Vec;
-use variable::Variable;
 
 /// Structure used for translating a series of functions into Cranelift IR.
 ///
@@ -822,15 +822,15 @@ impl<'a> FunctionBuilder<'a> {
 #[cfg(test)]
 mod tests {
     use super::greatest_divisible_power_of_two;
+    use crate::frontend::{FunctionBuilder, FunctionBuilderContext};
+    use crate::Variable;
     use cranelift_codegen::entity::EntityRef;
     use cranelift_codegen::ir::types::*;
     use cranelift_codegen::ir::{AbiParam, ExternalName, Function, InstBuilder, Signature};
     use cranelift_codegen::isa::CallConv;
     use cranelift_codegen::settings;
     use cranelift_codegen::verifier::verify_function;
-    use frontend::{FunctionBuilder, FunctionBuilderContext};
     use std::string::ToString;
-    use Variable;
 
     fn sample_function(lazy_seal: bool) {
         let mut sig = Signature::new(CallConv::SystemV);

lib/frontend/src/lib.rs

@@ -180,15 +180,10 @@
 #[cfg(not(feature = "std"))]
 #[macro_use]
 extern crate alloc;
-extern crate cranelift_codegen;
-#[cfg(test)]
-extern crate target_lexicon;
-#[macro_use]
-extern crate log;
 
-pub use frontend::{FunctionBuilder, FunctionBuilderContext};
-pub use switch::Switch;
-pub use variable::Variable;
+pub use crate::frontend::{FunctionBuilder, FunctionBuilderContext};
+pub use crate::switch::Switch;
+pub use crate::variable::Variable;
 
 mod frontend;
 mod ssa;

lib/frontend/src/ssa.rs

@@ -5,6 +5,7 @@
 //! In: Jhala R., De Bosschere K. (eds) Compiler Construction. CC 2013.
 //! Lecture Notes in Computer Science, vol 7791. Springer, Berlin, Heidelberg
 
+use crate::Variable;
 use cranelift_codegen::cursor::{Cursor, FuncCursor};
 use cranelift_codegen::entity::{EntityRef, PrimaryMap, SecondaryMap};
 use cranelift_codegen::ir::immediates::{Ieee32, Ieee64};
@@ -16,7 +17,6 @@ use cranelift_codegen::packed_option::ReservedValue;
 use std::mem;
 use std::u32;
 use std::vec::Vec;
-use Variable;
 
 /// Structure containing the data relevant the construction of SSA for a given function.
 ///
@@ -749,6 +749,8 @@ impl SSABuilder {
 
 #[cfg(test)]
 mod tests {
+    use crate::ssa::SSABuilder;
+    use crate::Variable;
     use cranelift_codegen::cursor::{Cursor, FuncCursor};
     use cranelift_codegen::entity::EntityRef;
     use cranelift_codegen::ir::instructions::BranchInfo;
@@ -756,8 +758,6 @@ mod tests {
     use cranelift_codegen::ir::{Function, Inst, InstBuilder, JumpTableData, Opcode};
     use cranelift_codegen::settings;
     use cranelift_codegen::verify_function;
-    use ssa::SSABuilder;
-    use Variable;
 
     #[test]
     fn simple_block() {

lib/frontend/src/switch.rs

@@ -1,6 +1,7 @@
+use crate::frontend::FunctionBuilder;
 use cranelift_codegen::ir::condcodes::IntCC;
 use cranelift_codegen::ir::*;
-use frontend::FunctionBuilder;
+use log::debug;
 use std::collections::HashMap;
 use std::vec::Vec;
 
@@ -200,8 +201,8 @@ impl ContiguousCaseRange {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::frontend::FunctionBuilderContext;
     use cranelift_codegen::ir::Function;
-    use frontend::FunctionBuilderContext;
     use std::string::ToString;
 
     macro_rules! setup {