From cef7764a7624fabeb151b861f005a9d89da91a09 Mon Sep 17 00:00:00 2001
From: Yuki Okushi <huyuumi.dev@gmail.com>
Date: Wed, 29 Jan 2020 18:02:58 +0900
Subject: [PATCH] Avoid ICE in macro's diagnostics

---
 src/librustc_parse/parser/item.rs             |  40 ++++++++++--------
 src/test/ui/parser/issue-62524.stderr         |   5 +--
 src/test/ui/parser/issue-68629.rs             | Bin 0 -> 336 bytes
 src/test/ui/parser/issue-68629.stderr         | Bin 0 -> 1441 bytes
 .../ui/parser/mbe_missing_right_paren.stderr  |   4 +-
 5 files changed, 27 insertions(+), 22 deletions(-)
 create mode 100644 src/test/ui/parser/issue-68629.rs
 create mode 100644 src/test/ui/parser/issue-68629.stderr

diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index 31db7fc5f75..11adc9fafd6 100644
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -1638,26 +1638,32 @@ impl<'a> Parser<'a> {
             .span_to_snippet(self.prev_span)
             .map(|s| s.ends_with(")") || s.ends_with("]"))
             .unwrap_or(false);
-        let right_brace_span = if has_close_delim {
-            // it's safe to peel off one character only when it has the close delim
-            self.prev_span.with_lo(self.prev_span.hi() - BytePos(1))
-        } else {
-            self.prev_span.shrink_to_hi()
-        };
 
-        self.struct_span_err(
+        let mut err = self.struct_span_err(
             self.prev_span,
             "macros that expand to items must be delimited with braces or followed by a semicolon",
-        )
-        .multipart_suggestion(
-            "change the delimiters to curly braces",
-            vec![
-                (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), "{".to_string()),
-                (right_brace_span, '}'.to_string()),
-            ],
-            Applicability::MaybeIncorrect,
-        )
-        .span_suggestion(
+        );
+
+        // To avoid ICE, we shouldn't emit actual suggestions when it hasn't closing delims
+        if has_close_delim {
+            err.multipart_suggestion(
+                "change the delimiters to curly braces",
+                vec![
+                    (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), '{'.to_string()),
+                    (self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
+                ],
+                Applicability::MaybeIncorrect,
+            );
+        } else {
+            err.span_suggestion(
+                self.prev_span,
+                "change the delimiters to curly braces",
+                " { /* items */ }".to_string(),
+                Applicability::MaybeIncorrect,
+            );
+        }
+
+        err.span_suggestion(
             self.prev_span.shrink_to_hi(),
             "add a semicolon",
             ';'.to_string(),
diff --git a/src/test/ui/parser/issue-62524.stderr b/src/test/ui/parser/issue-62524.stderr
index 3482435cd1d..8191c9682ce 100644
--- a/src/test/ui/parser/issue-62524.stderr
+++ b/src/test/ui/parser/issue-62524.stderr
@@ -16,9 +16,8 @@ LL | | Ϥ,
    |
 help: change the delimiters to curly braces
    |
-LL | y!{
-LL | Ϥ}
-   |
+LL | y! { /* items */ }
+   |    ^^^^^^^^^^^^^^^
 help: add a semicolon
    |
 LL | Ϥ,;
diff --git a/src/test/ui/parser/issue-68629.rs b/src/test/ui/parser/issue-68629.rs
new file mode 100644
index 0000000000000000000000000000000000000000..672a31f12c838bf7b2e54e6012354acea5852515
GIT binary patch
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snRyCe&lD%;7o>7=$;g)!Gblz^XL2zxC@7@mDHPq^ou6n|ba!_y0LS)tYybcN

literal 0
HcmV?d00001

diff --git a/src/test/ui/parser/issue-68629.stderr b/src/test/ui/parser/issue-68629.stderr
new file mode 100644
index 0000000000000000000000000000000000000000..a7885ecec5647e4c3eece95ce5b4ea25c70273ca
GIT binary patch
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zr-hX{QgkYyXJv)>`1trZNL<$_;E0<VkRmvagP50*np0q<kerd2m!7Inl7Vn^Q8CCv
z$)!a(l~9*MG=O6tQj#cCE9h%M{j8<00Lsab<f9OW3b-J)B&MXGc^6hPVYt{DY#BTy
zff<P8l$@BCmtUfgmYJ8L0FDTSgp%R}h0Ht!a6&6i&M!#C8<@sm<00V%@e86<L|BuU
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literal 0
HcmV?d00001

diff --git a/src/test/ui/parser/mbe_missing_right_paren.stderr b/src/test/ui/parser/mbe_missing_right_paren.stderr
index c5b3cc275ce..4ce39de8866 100644
--- a/src/test/ui/parser/mbe_missing_right_paren.stderr
+++ b/src/test/ui/parser/mbe_missing_right_paren.stderr
@@ -14,8 +14,8 @@ LL | macro_rules! abc(ؼ
    |
 help: change the delimiters to curly braces
    |
-LL | macro_rules! abc{ؼ}
-   |                 ^ ^
+LL | macro_rules! abc { /* items */ }
+   |                  ^^^^^^^^^^^^^^^
 help: add a semicolon
    |
 LL | macro_rules! abc(ؼ;