Rollup merge of rust-lang#144409 - GuillaumeGomez:macro-expansion-early-abort, r=oli-obk

Stop compilation early if macro expansion failed

Fixes rust-lang#116180.

So there isn't really a type that is central for macro expansion and some errors are actually emitted (because the resolution happens after the expansion I suppose) after the expansion pass (like "not found macro"). Sometimes, errors are only emitted on the second "try" (to improve error output). So I couldn't reach a similar solution than what was done in rust-lang#133937 and suggested by `@estebank` in rust-lang#116180 (comment). But maybe I missed something?

So in the end, I realized that there is method called every time (except one, described below) a macro error is actually emitted: `ExtCtxt::trace_macros_diag`. Considering I updated what it did, I renamed it into `macro_error_and_trace_macros_diag` to better reflect it.

There is only one call of `trace_macros_diag` which isn't reporting an error but just used for `macro_trace` feature, so I kept it as is.

r? `@oli-obk`

Author: matthiaskrgr

compiler/rustc_expand/src/base.rs

@@ -1224,6 +1224,7 @@ pub struct ExtCtxt<'a> {
     pub(super) expanded_inert_attrs: MarkedAttrs,
     /// `-Zmacro-stats` data.
     pub macro_stats: FxHashMap<(Symbol, MacroKind), MacroStat>,
+    pub nb_macro_errors: usize,
 }
 
 impl<'a> ExtCtxt<'a> {
@@ -1254,6 +1255,7 @@ impl<'a> ExtCtxt<'a> {
             expanded_inert_attrs: MarkedAttrs::new(),
             buffered_early_lint: vec![],
             macro_stats: Default::default(),
+            nb_macro_errors: 0,
         }
     }
 
@@ -1315,6 +1317,12 @@ impl<'a> ExtCtxt<'a> {
         self.current_expansion.id.expansion_cause()
     }
 
+    /// This method increases the internal macro errors count and then call `trace_macros_diag`.
+    pub fn macro_error_and_trace_macros_diag(&mut self) {
+        self.nb_macro_errors += 1;
+        self.trace_macros_diag();
+    }
+
     pub fn trace_macros_diag(&mut self) {
         for (span, notes) in self.expansions.iter() {
             let mut db = self.dcx().create_note(errors::TraceMacro { span: *span });

compiler/rustc_expand/src/expand.rs

@@ -693,7 +693,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             crate_name: self.cx.ecfg.crate_name,
         });
 
-        self.cx.trace_macros_diag();
+        self.cx.macro_error_and_trace_macros_diag();
         guar
     }
 
@@ -707,7 +707,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
     ) -> ErrorGuaranteed {
         let guar =
             self.cx.dcx().emit_err(WrongFragmentKind { span, kind: kind.name(), name: &mac.path });
-        self.cx.trace_macros_diag();
+        self.cx.macro_error_and_trace_macros_diag();
         guar
     }
 
@@ -1048,7 +1048,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 }
                 annotate_err_with_kind(&mut err, kind, span);
                 let guar = err.emit();
-                self.cx.trace_macros_diag();
+                self.cx.macro_error_and_trace_macros_diag();
                 kind.dummy(span, guar)
             }
         }

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -299,6 +299,7 @@ enum EofMatcherPositions {
 }
 
 /// Represents the possible results of an attempted parse.
+#[derive(Debug)]
 pub(crate) enum ParseResult<T, F> {
     /// Parsed successfully.
     Success(T),

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -280,7 +280,7 @@ fn expand_macro<'cx>(
             // Retry and emit a better error.
             let (span, guar) =
                 diagnostics::failed_to_match_macro(cx.psess(), sp, def_span, name, arg, rules);
-            cx.trace_macros_diag();
+            cx.macro_error_and_trace_macros_diag();
             DummyResult::any(span, guar)
         }
     }

compiler/rustc_interface/src/passes.rs

@@ -208,6 +208,10 @@ fn configure_and_expand(
         // Expand macros now!
         let krate = sess.time("expand_crate", || ecx.monotonic_expander().expand_crate(krate));
 
+        if ecx.nb_macro_errors > 0 {
+            sess.dcx().abort_if_errors();
+        }
+
         // The rest is error reporting and stats
 
         sess.psess.buffered_lints.with_lock(|buffered_lints: &mut Vec<BufferedEarlyLint>| {

tests/ui/const-generics/min_const_generics/macro-fail-const.rs

@@ -0,0 +1,23 @@
+trait Marker<const N: usize> {}
+struct Example<const N: usize>;
+impl<const N: usize> Marker<N> for Example<N> {}
+
+fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
+  //~^ ERROR: type provided when a constant was expected
+  //~| ERROR: type provided when a constant was expected
+  Example::<gimme_a_const!(marker)>
+  //~^ ERROR: type provided when a constant was expected
+}
+
+fn main() {
+  let _ok = Example::<{
+    #[macro_export]
+    macro_rules! gimme_a_const {
+      ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
+      //~^ ERROR expected type
+      //~| ERROR expected type
+    }
+    gimme_a_const!(run)
+  }>;
+  let _ok = Example::<{gimme_a_const!(marker)}>;
+}

tests/ui/const-generics/min_const_generics/macro-fail-const.stderr

@@ -0,0 +1,51 @@
+error: expected type, found `{`
+  --> $DIR/macro-fail-const.rs:16:27
+   |
+LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
+   |                                 ----------------------
+   |                                 |
+   |                                 this macro call doesn't expand to a type
+   |                                 in this macro invocation
+...
+LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
+   |                           ^ expected type
+   |
+   = note: this error originates in the macro `gimme_a_const` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: expected type, found `{`
+  --> $DIR/macro-fail-const.rs:16:27
+   |
+LL |   Example::<gimme_a_const!(marker)>
+   |             ----------------------
+   |             |
+   |             this macro call doesn't expand to a type
+   |             in this macro invocation
+...
+LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
+   |                           ^ expected type
+   |
+   = note: this error originates in the macro `gimme_a_const` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0747]: type provided when a constant was expected
+  --> $DIR/macro-fail-const.rs:5:33
+   |
+LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0747]: type provided when a constant was expected
+  --> $DIR/macro-fail-const.rs:5:33
+   |
+LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0747]: type provided when a constant was expected
+  --> $DIR/macro-fail-const.rs:8:13
+   |
+LL |   Example::<gimme_a_const!(marker)>
+   |             ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0747`.

tests/ui/const-generics/min_const_generics/macro-fail.rs

@@ -12,10 +12,7 @@ trait Marker<const N: usize> {}
 impl<const N: usize> Marker<N> for Example<N> {}
 
 fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
-  //~^ ERROR: type provided when a constant was expected
-  //~| ERROR: type provided when a constant was expected
   Example::<gimme_a_const!(marker)>
-  //~^ ERROR: type provided when a constant was expected
 }
 
 fn from_marker(_: impl Marker<{
@@ -35,9 +32,7 @@ fn main() {
   }>;
 
   let _fail = Example::<external_macro!()>;
-  //~^ ERROR: type provided when a constant
 
   let _fail = Example::<gimme_a_const!()>;
-  //~^ ERROR unexpected end of macro invocation
-  //~| ERROR: type provided when a constant was expected
+  //~^ ERROR: unexpected end of macro invocation
 }

tests/ui/const-generics/min_const_generics/macro-fail.stderr

@@ -1,5 +1,5 @@
 error: expected type, found `{`
-  --> $DIR/macro-fail.rs:30:27
+  --> $DIR/macro-fail.rs:27:27
    |
 LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
    |                                 ----------------------
@@ -13,7 +13,7 @@ LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
    = note: this error originates in the macro `gimme_a_const` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected type, found `{`
-  --> $DIR/macro-fail.rs:30:27
+  --> $DIR/macro-fail.rs:27:27
    |
 LL |   Example::<gimme_a_const!(marker)>
    |             ----------------------
@@ -41,7 +41,7 @@ LL |   let _fail = Example::<external_macro!()>;
    = note: this error originates in the macro `external_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: unexpected end of macro invocation
-  --> $DIR/macro-fail.rs:40:25
+  --> $DIR/macro-fail.rs:36:25
    |
 LL |     macro_rules! gimme_a_const {
    |     -------------------------- when calling this macro
@@ -50,43 +50,10 @@ LL |   let _fail = Example::<gimme_a_const!()>;
    |                         ^^^^^^^^^^^^^^^^ missing tokens in macro arguments
    |
 note: while trying to match meta-variable `$rusty:ident`
-  --> $DIR/macro-fail.rs:30:8
+  --> $DIR/macro-fail.rs:27:8
    |
 LL |       ($rusty: ident) => {{ let $rusty = 3; *&$rusty }}
    |        ^^^^^^^^^^^^^
 
-error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:14:33
-   |
-LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:14:33
-   |
-LL | fn make_marker() -> impl Marker<gimme_a_const!(marker)> {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:17:13
-   |
-LL |   Example::<gimme_a_const!(marker)>
-   |             ^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:37:25
-   |
-LL |   let _fail = Example::<external_macro!()>;
-   |                         ^^^^^^^^^^^^^^^^^
-
-error[E0747]: type provided when a constant was expected
-  --> $DIR/macro-fail.rs:40:25
-   |
-LL |   let _fail = Example::<gimme_a_const!()>;
-   |                         ^^^^^^^^^^^^^^^^
-
-error: aborting due to 9 previous errors
+error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0747`.

tests/ui/editions/edition-keywords-2018-2015-parsing.rs

@@ -26,7 +26,7 @@ pub fn check_async() {
     module::async(); //~ ERROR expected identifier, found keyword `async`
     module::r#async(); // OK
 
-    let _recovery_witness: () = 0; //~ ERROR mismatched types
+    let _recovery_witness: () = 0; // not emitted because of the macro parsing error
 }
 
 //~? ERROR macro expansion ends with an incomplete expression