Auto merge of #34374 - jseyfried:fix_hygiene_bug, r=nrc

Fix macro hygiene regression The regression was caused by #32923, which is currently in beta. The following is an example of regressed code: ```rust fn main() { let x = 0; macro_rules! foo { () => { println!("{}", x); // prints `0` on stable and after this PR, prints `1` on beta and nightly } } let x = 1; foo!(); } ``` For code to regress, the following is necessary (but not sufficient): - There must be a local variable before a macro in a block, and the macro must use the variable. - There must be a second local variable with the same name after the macro. - The macro must be invoked in a statement position after the second local variable. For example, if the `let x = 0;` from the breaking example were commented out, it would (correctly) not compile on beta/nightly. If the semicolon were removed from `foo!();`, it would (correctly) print `0` on beta and nightly. r? @nrc

Author: bors

src/libsyntax/ext/expand.rs

@@ -681,7 +681,7 @@ pub struct IdentRenamer<'a> {
 
 impl<'a> Folder for IdentRenamer<'a> {
  fn fold_ident(&mut self, id: Ident) -> Ident {
- Ident::new(id.name, mtwt::apply_renames(self.renames, id.ctxt))
+ mtwt::apply_renames(self.renames, id)
  }
  fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
  fold::noop_fold_mac(mac, self)
@@ -705,8 +705,7 @@ impl<'a> Folder for PatIdentRenamer<'a> {
 
  pat.map(|ast::Pat {id, node, span}| match node {
  PatKind::Ident(binding_mode, Spanned{span: sp, node: ident}, sub) => {
- let new_ident = Ident::new(ident.name,
- mtwt::apply_renames(self.renames, ident.ctxt));
+ let new_ident = mtwt::apply_renames(self.renames, ident);
  let new_node =
  PatKind::Ident(binding_mode,
  Spanned{span: sp, node: new_ident},
@@ -1266,7 +1265,7 @@ mod tests {
  use ext::mtwt;
  use fold::Folder;
  use parse;
- use parse::token::{self, keywords};
+ use parse::token;
  use util::parser_testing::{string_to_parser};
  use util::parser_testing::{string_to_pat, string_to_crate, strs_to_idents};
  use visit;
@@ -1396,267 +1395,10 @@ mod tests {
  );
  }
 
- // renaming tests expand a crate and then check that the bindings match
- // the right varrefs. The specification of the test case includes the
- // text of the crate, and also an array of arrays. Each element in the
- // outer array corresponds to a binding in the traversal of the AST
- // induced by visit. Each of these arrays contains a list of indexes,
- // interpreted as the varrefs in the varref traversal that this binding
- // should match. So, for instance, in a program with two bindings and
- // three varrefs, the array [[1, 2], [0]] would indicate that the first
- // binding should match the second two varrefs, and the second binding
- // should match the first varref.
- //
- // Put differently; this is a sparse representation of a boolean matrix
- // indicating which bindings capture which identifiers.
- //
- // Note also that this matrix is dependent on the implicit ordering of
- // the bindings and the varrefs discovered by the name-finder and the path-finder.
- //
- // The comparisons are done post-mtwt-resolve, so we're comparing renamed
- // names; differences in marks don't matter any more.
- //
- // oog... I also want tests that check "bound-identifier-=?". That is,
- // not just "do these have the same name", but "do they have the same
- // name *and* the same marks"? Understanding this is really pretty painful.
- // in principle, you might want to control this boolean on a per-varref basis,
- // but that would make things even harder to understand, and might not be
- // necessary for thorough testing.
- type RenamingTest = (&'static str, Vec<Vec<usize>>, bool);
-
- #[test]
- fn automatic_renaming () {
- let tests: Vec<RenamingTest> =
- vec!(// b & c should get new names throughout, in the expr too:
- ("fn a() -> i32 { let b = 13; let c = b; b+c }",
- vec!(vec!(0,1),vec!(2)), false),
- // both x's should be renamed (how is this causing a bug?)
- ("fn main () {let x: i32 = 13;x;}",
- vec!(vec!(0)), false),
- // the use of b after the + should be renamed, the other one not:
- ("macro_rules! f (($x:ident) => (b + $x)); fn a() -> i32 { let b = 13; f!(b)}",
- vec!(vec!(1)), false),
- // the b before the plus should not be renamed (requires marks)
- ("macro_rules! f (($x:ident) => ({let b=9; ($x + b)})); fn a() -> i32 { f!(b)}",
- vec!(vec!(1)), false),
- // the marks going in and out of letty should cancel, allowing that $x to
- // capture the one following the semicolon.
- // this was an awesome test case, and caught a *lot* of bugs.
- ("macro_rules! letty(($x:ident) => (let $x = 15;));
- macro_rules! user(($x:ident) => ({letty!($x); $x}));
- fn main() -> i32 {user!(z)}",
- vec!(vec!(0)), false)
- );
- for (idx,s) in tests.iter().enumerate() {
- run_renaming_test(s,idx);
- }
- }
-
- // no longer a fixme #8062: this test exposes a *potential* bug; our system does
- // not behave exactly like MTWT, but a conversation with Matthew Flatt
- // suggests that this can only occur in the presence of local-expand, which
- // we have no plans to support. ... unless it's needed for item hygiene....
- #[ignore]
- #[test]
- fn issue_8062(){
- run_renaming_test(
- &("fn main() {let hrcoo = 19; macro_rules! getx(()=>(hrcoo)); getx!();}",
- vec!(vec!(0)), true), 0)
- }
-
- // FIXME #6994:
- // the z flows into and out of two macros (g & f) along one path, and one
- // (just g) along the other, so the result of the whole thing should
- // be "let z_123 = 3; z_123"
- #[ignore]
- #[test]
- fn issue_6994(){
- run_renaming_test(
- &("macro_rules! g (($x:ident) =>
- ({macro_rules! f(($y:ident)=>({let $y=3;$x}));f!($x)}));
- fn a(){g!(z)}",
- vec!(vec!(0)),false),
- 0)
- }
-
- // match variable hygiene. Should expand into
- // fn z() {match 8 {x_1 => {match 9 {x_2 | x_2 if x_2 == x_1 => x_2 + x_1}}}}
- #[test]
- fn issue_9384(){
- run_renaming_test(
- &("macro_rules! bad_macro (($ex:expr) => ({match 9 {x | x if x == $ex => x + $ex}}));
- fn z() {match 8 {x => bad_macro!(x)}}",
- // NB: the third "binding" is the repeat of the second one.
- vec!(vec!(1,3),vec!(0,2),vec!(0,2)),
- true),
- 0)
- }
-
- // interpolated nodes weren't getting labeled.
- // should expand into
- // fn main(){let g1_1 = 13; g1_1}}
- #[test]
- fn pat_expand_issue_15221(){
- run_renaming_test(
- &("macro_rules! inner ( ($e:pat ) => ($e));
- macro_rules! outer ( ($e:pat ) => (inner!($e)));
- fn main() { let outer!(g) = 13; g;}",
- vec!(vec!(0)),
- true),
- 0)
- }
-
  // create a really evil test case where a $x appears inside a binding of $x
  // but *shouldn't* bind because it was inserted by a different macro....
  // can't write this test case until we have macro-generating macros.
 
- // method arg hygiene
- // method expands to fn get_x(&self_0, x_1: i32) {self_0 + self_2 + x_3 + x_1}
- #[test]
- fn method_arg_hygiene(){
- run_renaming_test(
- &("macro_rules! inject_x (()=>(x));
- macro_rules! inject_self (()=>(self));
- struct A;
- impl A{fn get_x(&self, x: i32) {self + inject_self!() + inject_x!() + x;} }",
- vec!(vec!(0),vec!(3)),
- true),
- 0)
- }
-
- // ooh, got another bite?
- // expands to struct A; impl A {fn thingy(&self_1) {self_1;}}
- #[test]
- fn method_arg_hygiene_2(){
- run_renaming_test(
- &("struct A;
- macro_rules! add_method (($T:ty) =>
- (impl $T { fn thingy(&self) {self;} }));
- add_method!(A);",
- vec!(vec!(0)),
- true),
- 0)
- }
-
- // item fn hygiene
- // expands to fn q(x_1: i32){fn g(x_2: i32){x_2 + x_1};}
- #[test]
- fn issue_9383(){
- run_renaming_test(
- &("macro_rules! bad_macro (($ex:expr) => (fn g(x: i32){ x + $ex }));
- fn q(x: i32) { bad_macro!(x); }",
- vec!(vec!(1),vec!(0)),true),
- 0)
- }
-
- // closure arg hygiene (ExprKind::Closure)
- // expands to fn f(){(|x_1 : i32| {(x_2 + x_1)})(3);}
- #[test]
- fn closure_arg_hygiene(){
- run_renaming_test(
- &("macro_rules! inject_x (()=>(x));
- fn f(){(|x : i32| {(inject_x!() + x)})(3);}",
- vec!(vec!(1)),
- true),
- 0)
- }
-
- // macro_rules in method position. Sadly, unimplemented.
- #[test]
- fn macro_in_method_posn(){
- expand_crate_str(
- "macro_rules! my_method (() => (fn thirteen(&self) -> i32 {13}));
- struct A;
- impl A{ my_method!(); }
- fn f(){A.thirteen;}".to_string());
- }
-
- // another nested macro
- // expands to impl Entries {fn size_hint(&self_1) {self_1;}
- #[test]
- fn item_macro_workaround(){
- run_renaming_test(
- &("macro_rules! item { ($i:item) => {$i}}
- struct Entries;
- macro_rules! iterator_impl {
- () => { item!( impl Entries { fn size_hint(&self) { self;}});}}
- iterator_impl! { }",
- vec!(vec!(0)), true),
- 0)
- }
-
- // run one of the renaming tests
- fn run_renaming_test(t: &RenamingTest, test_idx: usize) {
- let invalid_name = keywords::Invalid.name();
- let (teststr, bound_connections, bound_ident_check) = match *t {
- (ref str,ref conns, bic) => (str.to_string(), conns.clone(), bic)
- };
- let cr = expand_crate_str(teststr.to_string());
- let bindings = crate_bindings(&cr);
- let varrefs = crate_varrefs(&cr);
-
- // must be one check clause for each binding:
- assert_eq!(bindings.len(),bound_connections.len());
- for (binding_idx,shouldmatch) in bound_connections.iter().enumerate() {
- let binding_name = mtwt::resolve(bindings[binding_idx]);
- let binding_marks = mtwt::marksof(bindings[binding_idx].ctxt, invalid_name);
- // shouldmatch can't name varrefs that don't exist:
- assert!((shouldmatch.is_empty()) ||
- (varrefs.len() > *shouldmatch.iter().max().unwrap()));
- for (idx,varref) in varrefs.iter().enumerate() {
- let print_hygiene_debug_info = || {
- // good lord, you can't make a path with 0 segments, can you?
- let final_varref_ident = match varref.segments.last() {
- Some(pathsegment) => pathsegment.identifier,
- None => panic!("varref with 0 path segments?")
- };
- let varref_name = mtwt::resolve(final_varref_ident);
- let varref_idents : Vec<ast::Ident>
- = varref.segments.iter().map(|s| s.identifier)
- .collect();
- println!("varref #{}: {:?}, resolves to {}",idx, varref_idents, varref_name);
- println!("varref's first segment's string: \"{}\"", final_varref_ident);
- println!("binding #{}: {}, resolves to {}",
- binding_idx, bindings[binding_idx], binding_name);
- mtwt::with_sctable(|x| mtwt::display_sctable(x));
- };
- if shouldmatch.contains(&idx) {
- // it should be a path of length 1, and it should
- // be free-identifier=? or bound-identifier=? to the given binding
- assert_eq!(varref.segments.len(),1);
- let varref_name = mtwt::resolve(varref.segments[0].identifier);
- let varref_marks = mtwt::marksof(varref.segments[0]
- .identifier
- .ctxt,
- invalid_name);
- if !(varref_name==binding_name) {
- println!("uh oh, should match but doesn't:");
- print_hygiene_debug_info();
- }
- assert_eq!(varref_name,binding_name);
- if bound_ident_check {
- // we're checking bound-identifier=?, and the marks
- // should be the same, too:
- assert_eq!(varref_marks,binding_marks.clone());
- }
- } else {
- let varref_name = mtwt::resolve(varref.segments[0].identifier);
- let fail = (varref.segments.len() == 1)
- && (varref_name == binding_name);
- // temp debugging:
- if fail {
- println!("failure on test {}",test_idx);
- println!("text of test case: \"{}\"", teststr);
- println!("");
- println!("uh oh, matches but shouldn't:");
- print_hygiene_debug_info();
- }
- assert!(!fail);
- }
- }
- }
- }
-
  #[test]
  fn fmt_in_macro_used_inside_module_macro() {
  let crate_str = "macro_rules! fmt_wrap(($b:expr)=>($b.to_string()));