Rollup merge of #104335 - Nilstrieb:macrowo, r=compiler-errors

Only do parser recovery on retried macro matching

Eager parser recovery can break macros, so we don't do it at first. But when we already know that the macro failed, we can retry it with recovery enabled to still emit useful diagnostics.

Helps with #103534

3 files changed, 31 insertions, 0 deletions

diff --git a/src/test/ui/macros/recovery-allowed.rs b/src/test/ui/macros/recovery-allowed.rs
new file mode 100644
index 00000000000..ebf65f1cc01
--- /dev/null
+++ b/src/test/ui/macros/recovery-allowed.rs
@@ -0,0 +1,8 @@
+macro_rules! please_recover {
+    ($a:expr) => {};
+}
+
+please_recover! { not 1 }
+//~^ ERROR unexpected `1` after identifier
+
+fn main() {}
diff --git a/src/test/ui/macros/recovery-allowed.stderr b/src/test/ui/macros/recovery-allowed.stderr
new file mode 100644
index 00000000000..ec036e8b1e2
--- /dev/null
+++ b/src/test/ui/macros/recovery-allowed.stderr
@@ -0,0 +1,10 @@
+error: unexpected `1` after identifier
+  --> $DIR/recovery-allowed.rs:5:23
+   |
+LL | please_recover! { not 1 }
+   |                   ----^
+   |                   |
+   |                   help: use `!` to perform bitwise not
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/macros/recovery-forbidden.rs b/src/test/ui/macros/recovery-forbidden.rs
new file mode 100644
index 00000000000..5dd2619330c
--- /dev/null
+++ b/src/test/ui/macros/recovery-forbidden.rs
@@ -0,0 +1,13 @@
+// check-pass
+
+macro_rules! dont_recover_here {
+    ($e:expr) => {
+        compile_error!("Must not recover to single !1 expr");
+    };
+
+    (not $a:literal) => {};
+}
+
+dont_recover_here! { not 1 }
+
+fn main() {}