Rollup merge of rust-lang#32494 - pnkfelix:gate-parser-recovery-via-debugflag, r=nrc

Gate parser recovery via debugflag

Gate parser recovery via debugflag

Put in `-Z continue_parse_after_error`

This works by adding a method, `fn abort_if_no_parse_recovery`, to the
diagnostic handler in `syntax::errors`, and calling it after each
error is emitted in the parser.

(We might consider adding a debugflag to do such aborts in other
places where we are currently attempting recovery, such as resolve,
but I think the parser is the really important case to handle in the
face of rust-lang#31994 and the parser bugs of varying degrees that were
injected by parse error recovery.)

r? @nikomatsakis

Author: Manishearth

src/librustc/session/config.rs

@@ -136,6 +136,7 @@ pub struct Options {
     pub no_trans: bool,
     pub error_format: ErrorOutputType,
     pub treat_err_as_bug: bool,
+    pub continue_parse_after_error: bool,
     pub mir_opt_level: usize,
 
     /// if true, build up the dep-graph
@@ -257,6 +258,7 @@ pub fn basic_options() -> Options {
         parse_only: false,
         no_trans: false,
         treat_err_as_bug: false,
+        continue_parse_after_error: false,
         mir_opt_level: 1,
         build_dep_graph: false,
         dump_dep_graph: false,
@@ -631,6 +633,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "run all passes except translation; no output"),
     treat_err_as_bug: bool = (false, parse_bool,
           "treat all errors that occur as bugs"),
+    continue_parse_after_error: bool = (false, parse_bool,
+          "attempt to recover from parse errors (experimental)"),
     incr_comp: bool = (false, parse_bool,
           "enable incremental compilation (experimental)"),
     dump_dep_graph: bool = (false, parse_bool,
@@ -1045,6 +1049,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let parse_only = debugging_opts.parse_only;
     let no_trans = debugging_opts.no_trans;
     let treat_err_as_bug = debugging_opts.treat_err_as_bug;
+    let continue_parse_after_error = debugging_opts.continue_parse_after_error;
     let mir_opt_level = debugging_opts.mir_opt_level.unwrap_or(1);
     let incremental_compilation = debugging_opts.incr_comp;
     let dump_dep_graph = debugging_opts.dump_dep_graph;
@@ -1224,6 +1229,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         parse_only: parse_only,
         no_trans: no_trans,
         treat_err_as_bug: treat_err_as_bug,
+        continue_parse_after_error: continue_parse_after_error,
         mir_opt_level: mir_opt_level,
         build_dep_graph: incremental_compilation || dump_dep_graph,
         dump_dep_graph: dump_dep_graph,

src/librustc_driver/driver.rs

@@ -429,6 +429,8 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session,
     // memory, but they do not restore the initial state.
     syntax::ext::mtwt::reset_tables();
     token::reset_ident_interner();
+    let continue_after_error = sess.opts.continue_parse_after_error;
+    sess.diagnostic().set_continue_after_error(continue_after_error);
 
     let krate = time(sess.time_passes(), "parsing", || {
         match *input {
@@ -444,6 +446,8 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session,
         }
     })?;
 
+    sess.diagnostic().set_continue_after_error(true);
+
     if sess.opts.debugging_opts.ast_json_noexpand {
         println!("{}", json::as_json(&krate));
     }

src/libsyntax/errors/mod.rs

@@ -370,6 +370,7 @@ pub struct Handler {
     emit: RefCell<Box<Emitter>>,
     pub can_emit_warnings: bool,
     treat_err_as_bug: bool,
+    continue_after_error: Cell<bool>,
     delayed_span_bug: RefCell<Option<(MultiSpan, String)>>,
 }
 
@@ -392,10 +393,15 @@ impl Handler {
             emit: RefCell::new(e),
             can_emit_warnings: can_emit_warnings,
             treat_err_as_bug: treat_err_as_bug,
+            continue_after_error: Cell::new(true),
             delayed_span_bug: RefCell::new(None),
         }
     }
 
+    pub fn set_continue_after_error(&self, continue_after_error: bool) {
+        self.continue_after_error.set(continue_after_error);
+    }
+
     pub fn struct_dummy<'a>(&'a self) -> DiagnosticBuilder<'a> {
         DiagnosticBuilder::new(&self.emit, Level::Cancelled, "")
     }
@@ -612,6 +618,7 @@ impl Handler {
                 lvl: Level) {
         if lvl == Warning && !self.can_emit_warnings { return }
         self.emit.borrow_mut().emit(msp, msg, None, lvl);
+        if !self.continue_after_error.get() { self.abort_if_errors(); }
     }
     pub fn emit_with_code(&self,
                           msp: Option<&MultiSpan>,
@@ -620,10 +627,12 @@ impl Handler {
                           lvl: Level) {
         if lvl == Warning && !self.can_emit_warnings { return }
         self.emit.borrow_mut().emit(msp, msg, Some(code), lvl);
+        if !self.continue_after_error.get() { self.abort_if_errors(); }
     }
     pub fn custom_emit(&self, rsp: RenderSpan, msg: &str, lvl: Level) {
         if lvl == Warning && !self.can_emit_warnings { return }
         self.emit.borrow_mut().custom_emit(&rsp, msg, lvl);
+        if !self.continue_after_error.get() { self.abort_if_errors(); }
     }
 }
 

src/test/compile-fail/issue-12560-2.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 // For style and consistency reasons, non-parametrized enum variants must
 // be used simply as `ident` instead of `ident ()`.
 // This test-case covers enum matching.

src/test/compile-fail/issue-28433.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 enum bird {
     pub duck,
     //~^ ERROR: expected identifier, found keyword `pub`

src/test/compile-fail/issue-30715.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 macro_rules! parallel {
     (
         // If future has `pred`/`moelarry` fragments (where "pred" is

src/test/compile-fail/macro-incomplete-parse.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 macro_rules! ignored_item {
     () => {
         fn foo() {}

src/test/compile-fail/parse-error-correct.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 // Test that the parser is error correcting missing idents. Despite a parsing
 // error (or two), we still run type checking (and don't get extra errors there).
 

src/test/compile-fail/parser-recovery-1.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 // Test that we can recover from missing braces in the parser.
 
 trait Foo {

src/test/compile-fail/parser-recovery-2.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 // Test that we can recover from mismatched braces in the parser.
 
 trait Foo {

src/test/compile-fail/self_type_keyword.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z continue-parse-after-error
+
 struct Self;
 //~^ ERROR expected identifier, found keyword `Self`
 

src/test/parse-fail/ascii-only-character-escape.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 fn main() {
     let x = "\x80"; //~ ERROR may only be used

src/test/parse-fail/bad-char-literals.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 // ignore-tidy-cr
 // ignore-tidy-tab

src/test/parse-fail/bad-lit-suffixes.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 
 extern

src/test/parse-fail/byte-literals.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 
 // ignore-tidy-tab

src/test/parse-fail/byte-string-literals.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 
 // ignore-tidy-tab

src/test/parse-fail/issue-10412.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 
 trait Serializable<'self, T> { //~ ERROR no longer a special lifetime

src/test/parse-fail/issue-23620-invalid-escapes.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z parse-only -Z continue-parse-after-error
+
 fn main() {
     let _ = b"\u{a66e}";
     //~^ ERROR unicode escape sequences cannot be used as a byte or in a byte string

src/test/parse-fail/lex-bad-binary-literal.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-flags: -Z parse-only -Z continue-parse-after-error
+
 fn main() {
     0b121; //~ ERROR invalid digit for a base 2 literal
     0b10_10301; //~ ERROR invalid digit for a base 2 literal

src/test/parse-fail/lex-bad-char-literals-1.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 static c3: char =
     '\x1' //~ ERROR: numeric character escape is too short
 ;

src/test/parse-fail/lex-bad-numeric-literals.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 fn main() {
     0o1.0; //~ ERROR: octal float literal is not supported

src/test/parse-fail/lex-bare-cr-string-literal-doc-comment.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 // ignore-tidy-cr
 

src/test/parse-fail/new-unicode-escapes-4.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 pub fn main() {
     let s = "\u{lol}";

src/test/parse-fail/no-unsafe-self.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z parse-only
+// compile-flags: -Z parse-only -Z continue-parse-after-error
 
 trait A {
     fn foo(*mut self); //~ ERROR cannot pass self by raw pointer