Put in `-Z continue-parse-after-error`

This works by adding a boolean flag, `continue_after_error`, to
`syntax::errors::Handler` that can be imperatively set to `true` or
`false` via a new `fn set_continue_after_error`.

The flag starts off true (since we generally try to recover from
compiler errors, and `Handler` is shared across all phases).

Then, during the `phase_1_parse_input`, we consult the setting of the
`-Z continue-parse-after-error` debug flag to determine whether we
should leave the flag set to `true` or should change it to `false`.

----

(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 #31994 and the parser bugs of varying degrees that were
injected by parse error recovery.)

1 files changed, 9 insertions, 0 deletions

diff --git a/src/libsyntax/errors/mod.rs b/src/libsyntax/errors/mod.rs
index 9e1cb60f54f..c8c12d5a883 100644
--- a/src/libsyntax/errors/mod.rs
+++ b/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(); }
     }
 }