Add -Z dont-buffer-diagnostics, a way to force NLL to immediately emit its diagnostics.
This is mainly intended for `rustc` developers who want to see a
diagnostic in its original context in the control flow. Two uses
cases for that are:
* `-Z treat-err-as-bug` which then allows extraction of a stack-trace to the origin of the error
(a case that is so important that we make that flag imply this one, effectively).
* `RUST_LOG=... rustc`, in which case it is often useful to see the logging statements that
occurred immediately prior to the point where the diagnostic was signalled.
Drive-by: Added some documentation pointing future devs at
HandlerFlags, and documented the fields of `HandlerFlags` itself.
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 2a9732b..2569812 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1331,6 +1331,8 @@
"disable user provided type assertion in NLL"),
nll_dont_emit_read_for_match: bool = (false, parse_bool, [UNTRACKED],
"in match codegen, do not include ReadForMatch statements (used by mir-borrowck)"),
+ dont_buffer_diagnostics: bool = (false, parse_bool, [UNTRACKED],
+ "emit diagnostics rather than buffering (breaks NLL error downgrading, sorting)."),
polonius: bool = (false, parse_bool, [UNTRACKED],
"enable polonius-based borrow-checker"),
codegen_time_graph: bool = (false, parse_bool, [UNTRACKED],
diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 619262a..52e1ab4 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -1012,6 +1012,7 @@
let can_emit_warnings = !(warnings_allow || cap_lints_allow);
let treat_err_as_bug = sopts.debugging_opts.treat_err_as_bug;
+ let dont_buffer_diagnostics = sopts.debugging_opts.dont_buffer_diagnostics;
let report_delayed_bugs = sopts.debugging_opts.report_delayed_bugs;
let external_macro_backtrace = sopts.debugging_opts.external_macro_backtrace;
@@ -1059,6 +1060,7 @@
can_emit_warnings,
treat_err_as_bug,
report_delayed_bugs,
+ dont_buffer_diagnostics,
external_macro_backtrace,
..Default::default()
},
diff --git a/src/librustc_errors/diagnostic_builder.rs b/src/librustc_errors/diagnostic_builder.rs
index 1b34898..5e962a4 100644
--- a/src/librustc_errors/diagnostic_builder.rs
+++ b/src/librustc_errors/diagnostic_builder.rs
@@ -21,6 +21,10 @@
use syntax_pos::{MultiSpan, Span};
/// Used for emitting structured error messages and other diagnostic information.
+///
+/// If there is some state in a downstream crate you would like to
+/// access in the methods of `DiagnosticBuilder` here, consider
+/// extending `HandlerFlags`, accessed via `self.handler.flags`.
#[must_use]
#[derive(Clone)]
pub struct DiagnosticBuilder<'a> {
@@ -89,8 +93,14 @@
self.cancel();
}
- /// Buffers the diagnostic for later emission.
- pub fn buffer(self, buffered_diagnostics: &mut Vec<Diagnostic>) {
+ /// Buffers the diagnostic for later emission, unless handler
+ /// has disabled such buffering.
+ pub fn buffer(mut self, buffered_diagnostics: &mut Vec<Diagnostic>) {
+ if self.handler.flags.dont_buffer_diagnostics || self.handler.flags.treat_err_as_bug {
+ self.emit();
+ return;
+ }
+
// We need to use `ptr::read` because `DiagnosticBuilder`
// implements `Drop`.
let diagnostic;
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index 3582c23..d0ea6fb 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -303,9 +303,20 @@
#[derive(Default)]
pub struct HandlerFlags {
+ /// If false, warning-level lints are suppressed.
+ /// (rustc: see `--allow warnings` and `--cap-lints`)
pub can_emit_warnings: bool,
+ /// If true, error-level diagnostics are upgraded to bug-level.
+ /// (rustc: see `-Z treat-err-as-bug`)
pub treat_err_as_bug: bool,
+ /// If true, immediately emit diagnostics that would otherwise be buffered.
+ /// (rustc: see `-Z dont-buffer-diagnostics` and `-Z treat-err-as-bug`)
+ pub dont_buffer_diagnostics: bool,
+ /// If true, immediately print bugs registered with `delay_span_bug`.
+ /// (rustc: see `-Z report-delayed-bugs`)
pub report_delayed_bugs: bool,
+ /// show macro backtraces even for non-local macros.
+ /// (rustc: see `-Z external-macro-backtrace`)
pub external_macro_backtrace: bool,
}
