Turn error into a warning

Author: estebank

src/libsyntax/ext/tt/macro_rules.rs

@@ -788,7 +788,7 @@ fn check_matcher_core(sess: &ParseSess,
                                 } else {
                                     format!("`{}`", quoted_tt_to_string(tok))
                                 };
-                                let mut err = sess.span_diagnostic.struct_span_err(
+                                let mut err = sess.span_diagnostic.struct_span_warn(
                                     *sp,
                                     &format!(
                                         "`${name}:{frag}` is followed (through repetition) by \

src/test/ui/issues/issue-42755.rs

@@ -11,7 +11,7 @@
 
 macro_rules! foo {
     ($($p:vis)*) => {}
-    //~^ ERROR `$p:vis` is followed (through repetition) by itself, which is not allowed for `vis`
+    //~^ WARN `$p:vis` is followed (through repetition) by itself, which is not allowed for `vis`
     //~| ERROR repetition matches empty token tree
 }
 

src/test/ui/issues/issue-42755.stderr

@@ -1,4 +1,4 @@
-error: `$p:vis` is followed (through repetition) by itself, which is not allowed for `vis` fragments
+warning: `$p:vis` is followed (through repetition) by itself, which is not allowed for `vis` fragments
   --> $DIR/issue-42755.rs:13:8
    |
 LL |     ($($p:vis)*) => {}
@@ -16,5 +16,5 @@ error: repetition matches empty token tree
 LL |     ($($p:vis)*) => {}
    |       ^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 

src/test/ui/macros/incorrrect-repetition-2.rs

@@ -1,4 +1,4 @@
 macro_rules! foo {
     ($($a:expr)*) => {};
-    //~^ ERROR `$a:expr` is followed (through repetition) by itself, which is not allowed for
+    //~^ WARN `$a:expr` is followed (through repetition) by itself, which is not allowed for
 }

src/test/ui/macros/incorrrect-repetition-2.stderr

@@ -1,4 +1,4 @@
-error: `$a:expr` is followed (through repetition) by itself, which is not allowed for `expr` fragments
+warning: `$a:expr` is followed (through repetition) by itself, which is not allowed for `expr` fragments
   --> $DIR/incorrrect-repetition-2.rs:2:8
    |
 LL |     ($($a:expr)*) => {};
@@ -14,6 +14,6 @@ error[E0601]: `main` function not found in crate `incorrrect_repetition_2`
    |
    = note: consider adding a `main` function to `$DIR/incorrrect-repetition-2.rs`
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0601`.

src/test/ui/macros/incorrrect-repetition.rs

@@ -1,8 +1,10 @@
 macro_rules! sneaky {
     ($($i:ident $e:expr)*) => {}
-    //~^ ERROR `$e:expr` is followed (through repetition) by `$i:ident`, which is not allowed for
+    //~^ WARN `$e:expr` is followed (through repetition) by `$i:ident`, which is not allowed for
 }
 
 fn main() {
     sneaky!(a b c d);
+    let x: () = 1;
+    //~^ ERROR
 }

src/test/ui/macros/incorrrect-repetition.stderr

@@ -1,4 +1,4 @@
-error: `$e:expr` is followed (through repetition) by `$i:ident`, which is not allowed for `expr` fragments
+warning: `$e:expr` is followed (through repetition) by `$i:ident`, which is not allowed for `expr` fragments
   --> $DIR/incorrrect-repetition.rs:2:17
    |
 LL |     ($($i:ident $e:expr)*) => {}
@@ -12,5 +12,15 @@ help: add a valid separator for the repetition to be unambiguous, for example
 LL |     ($($i:ident $e:expr);*) => {}
    |                         ^
 
+error[E0308]: mismatched types
+  --> $DIR/incorrrect-repetition.rs:8:17
+   |
+LL |     let x: () = 1;
+   |                 ^ expected (), found integral variable
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/macros/macro-input-future-proofing.rs

@@ -29,7 +29,7 @@ macro_rules! errors_everywhere {
     ( $a:expr $($b:tt)* ) => { };
     //~^ ERROR `$a:expr` is followed by `$b:tt`, which is not allowed for `expr` fragments
     ( $($a:expr)* $($b:tt)* ) => { };
-    //~^ ERROR `$a:expr` is followed (through repetition) by itself, which is not allowed for
+    //~^ WARN `$a:expr` is followed (through repetition) by itself, which is not allowed for
     //~| ERROR `$a:expr` is followed by `$b:tt`, which is not allowed for `expr` fragments
     ( $($a:expr),* $($b:tt)* ) => { };
     //~^ ERROR `$a:expr` may be followed by `$b:tt`, which is not allowed for `expr` fragments

src/test/ui/macros/macro-input-future-proofing.stderr

@@ -70,7 +70,7 @@ LL |     ( $a:expr $($b:tt)* ) => { };
    |
    = note: allowed there are: `;`, `=>` or `,`
 
-error: `$a:expr` is followed (through repetition) by itself, which is not allowed for `expr` fragments
+warning: `$a:expr` is followed (through repetition) by itself, which is not allowed for `expr` fragments
   --> $DIR/macro-input-future-proofing.rs:31:9
    |
 LL |     ( $($a:expr)* $($b:tt)* ) => { };
@@ -98,5 +98,5 @@ LL |     ( $($a:expr),* $($b:tt)* ) => { };
    |
    = note: allowed there are: `;`, `=>` or `,`
 
-error: aborting due to 12 previous errors
+error: aborting due to 11 previous errors