From 770013d315e9a905e92794876b604568d2fb568e Mon Sep 17 00:00:00 2001
From: EliseZeroTwo <mail@elise.moe>
Date: Wed, 13 Dec 2023 18:46:03 -0700
Subject: [PATCH] fix: Overlapping spans in delimited meta-vars

---
 compiler/rustc_expand/src/mbe/macro_rules.rs |  7 +++
 tests/ui/macros/issue-118786.rs              | 16 +++++++
 tests/ui/macros/issue-118786.stderr          | 47 ++++++++++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 tests/ui/macros/issue-118786.rs
 create mode 100644 tests/ui/macros/issue-118786.stderr

diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 19734394382..0b3ef829219 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -236,6 +236,13 @@ fn expand_macro<'cx>(
                             target_sp.open = source_sp.open.with_ctxt(ctxt);
                             target_sp.close = source_sp.close.with_ctxt(ctxt);
                         }
+                        (
+                            TokenTree::Delimited(target_sp, ..),
+                            mbe::TokenTree::MetaVar(source_sp, ..),
+                        ) => {
+                            target_sp.open = source_sp.with_ctxt(ctxt);
+                            target_sp.close = source_sp.with_ctxt(ctxt).shrink_to_hi();
+                        }
                         _ => {
                             let sp = rhs_tt.span().with_ctxt(ctxt);
                             tt.set_span(sp);
diff --git a/tests/ui/macros/issue-118786.rs b/tests/ui/macros/issue-118786.rs
new file mode 100644
index 00000000000..84af3a65113
--- /dev/null
+++ b/tests/ui/macros/issue-118786.rs
@@ -0,0 +1,16 @@
+// compile-flags: --crate-type lib -O -C debug-assertions=yes
+
+// Regression test for issue 118786
+
+macro_rules! make_macro {
+    ($macro_name:tt) => {
+        macro_rules! $macro_name {
+        //~^ ERROR macros that expand to items must be delimited with braces or followed by a semicolon
+        //~| ERROR macro expansion ignores token `{` and any following
+        //~| ERROR cannot find macro `macro_rules` in this scope
+            () => {}
+        }
+    }
+}
+
+make_macro!((meow));
diff --git a/tests/ui/macros/issue-118786.stderr b/tests/ui/macros/issue-118786.stderr
new file mode 100644
index 00000000000..ca3a40f31c1
--- /dev/null
+++ b/tests/ui/macros/issue-118786.stderr
@@ -0,0 +1,47 @@
+error: macros that expand to items must be delimited with braces or followed by a semicolon
+  --> $DIR/issue-118786.rs:7:22
+   |
+LL |         macro_rules! $macro_name {
+   |                      ^^^^^^^^^^^
+   |
+help: change the delimiters to curly braces
+   |
+LL |         macro_rules! {} {
+   |                      ~          +
+help: add a semicolon
+   |
+LL |         macro_rules! $macro_name; {
+   |                                 +
+
+error: macro expansion ignores token `{` and any following
+  --> $DIR/issue-118786.rs:7:34
+   |
+LL |         macro_rules! $macro_name {
+   |                                  ^
+...
+LL | make_macro!((meow));
+   | ------------------- caused by the macro expansion here
+   |
+   = note: the usage of `make_macro!` is likely invalid in item context
+
+error: cannot find macro `macro_rules` in this scope
+  --> $DIR/issue-118786.rs:7:9
+   |
+LL |         macro_rules! $macro_name {
+   |         ^^^^^^^^^^^
+...
+LL | make_macro!((meow));
+   | ------------------- in this macro invocation
+   |
+note: maybe you have forgotten to define a name for this `macro_rules!`
+  --> $DIR/issue-118786.rs:7:9
+   |
+LL |         macro_rules! $macro_name {
+   |         ^^^^^^^^^^^
+...
+LL | make_macro!((meow));
+   | ------------------- in this macro invocation
+   = note: this error originates in the macro `make_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+