From 97ce1f54497b3b39ba9e1b710f69a0cbb71af7bd Mon Sep 17 00:00:00 2001
From: Jon Meow <46229924+jonmeow@users.noreply.github.com>
Date: Thu, 9 Dec 2021 08:10:36 -0800
Subject: [PATCH] Fix handling of closing scopes in FindNextof (#977)

---
 toolchain/lexer/token_kind.h                    |   4 ++--
 .../386740becc4c02670666928a4699c330b2fe1152    | Bin 0 -> 343 bytes
 .../937ffb0f00790f35ae9b578df0bcfa40b06fd2e8    | Bin 0 -> 556 bytes
 .../eddd593ed1b3ecde2f2b4ddf2ba4a4fbb83a6028    | Bin 0 -> 27 bytes
 toolchain/parser/parse_tree_test.cpp            |  16 ++++++++++++++++
 toolchain/parser/parser_impl.cpp                |   2 ++
 6 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 toolchain/parser/fuzzer_corpus/386740becc4c02670666928a4699c330b2fe1152
 create mode 100644 toolchain/parser/fuzzer_corpus/937ffb0f00790f35ae9b578df0bcfa40b06fd2e8
 create mode 100644 toolchain/parser/fuzzer_corpus/eddd593ed1b3ecde2f2b4ddf2ba4a4fbb83a6028

diff --git a/toolchain/lexer/token_kind.h b/toolchain/lexer/token_kind.h
index 3828add4420f..a0c0bf6f1a67 100644
--- a/toolchain/lexer/token_kind.h
+++ b/toolchain/lexer/token_kind.h
@@ -64,12 +64,12 @@ class TokenKind {
   // The token kind must be an opening symbol.
   [[nodiscard]] auto GetClosingSymbol() const -> TokenKind;
 
-  // Test whether this kind of token is an closing symbol for a group.
+  // Test whether this kind of token is a closing symbol for a group.
   [[nodiscard]] auto IsClosingSymbol() const -> bool;
 
   // Returns the associated opening symbol for a closing symbol.
   //
-  // The token kind must be an closing symbol.
+  // The token kind must be a closing symbol.
   [[nodiscard]] auto GetOpeningSymbol() const -> TokenKind;
 
   // Test whether this kind of token is a keyword.
diff --git a/toolchain/parser/fuzzer_corpus/386740becc4c02670666928a4699c330b2fe1152 b/toolchain/parser/fuzzer_corpus/386740becc4c02670666928a4699c330b2fe1152
new file mode 100644
index 0000000000000000000000000000000000000000..e4b750f75fd147f5cea219727ff807c58c9a8e66
GIT binary patch
literal 343
zcmWe*kTSl({=3=c^YmG_{u#cWuC$Jei<=7wEKJO~$`XsXxb*e8xNNz&w6(Q$b(6U?
zxEvfofJ+wxfOK(jRoCjF%H#pL$siMu0jd%RPtg`gYXUKt0aZ~2rj4LHBsqv8qRa$o
xMm7_~udxMs2ne)54%5YIKFB!;z@=3T@-y5*kY+GP*Tlra%*?<R?n5mtE&v#zJLdoZ

literal 0
HcmV?d00001

diff --git a/toolchain/parser/fuzzer_corpus/937ffb0f00790f35ae9b578df0bcfa40b06fd2e8 b/toolchain/parser/fuzzer_corpus/937ffb0f00790f35ae9b578df0bcfa40b06fd2e8
new file mode 100644
index 0000000000000000000000000000000000000000..4e3c7f42a0a0b5c2d7eec21e3c24db7a8f54e7e9
GIT binary patch
literal 556
zcmZQzC`&A|u}!qqhEPR7W|6IJqAm(h)vbo|G3D{efi$V=RzdaZK<FBT>9$}?Q!7eR
zi}Ij~Y6v(4W*DYJKn5TzgBVwfVHwOCbVq;#02B}?!2u5kBw@HBs8J9KVe@eFCM;=a
F0{{|Kh;#q|

literal 0
HcmV?d00001

diff --git a/toolchain/parser/fuzzer_corpus/eddd593ed1b3ecde2f2b4ddf2ba4a4fbb83a6028 b/toolchain/parser/fuzzer_corpus/eddd593ed1b3ecde2f2b4ddf2ba4a4fbb83a6028
new file mode 100644
index 0000000000000000000000000000000000000000..7a07a324e14b3fd30ba07493648c9a6a9e457ccd
GIT binary patch
literal 27
gcmZQzC`&A|wXt>6(2cg&(M`0o1%g;zT^$`w09y_QSpWb4

literal 0
HcmV?d00001

diff --git a/toolchain/parser/parse_tree_test.cpp b/toolchain/parser/parse_tree_test.cpp
index f66a41569206..5ebd99c839ae 100644
--- a/toolchain/parser/parse_tree_test.cpp
+++ b/toolchain/parser/parse_tree_test.cpp
@@ -1159,5 +1159,21 @@ TEST_F(ParseTreeTest, PrintingAsYAML) {
                              {"text", ""}}}));
 }
 
+TEST_F(ParseTreeTest, ParenMatchRegression) {
+  // A regression test that the search for the closing `)` doesn't end early on
+  // the closing `}` when it skips over the nested scope.
+  TokenizedBuffer tokens = GetTokenizedBuffer("var = (foo {})");
+  ParseTree tree = ParseTree::Parse(tokens, consumer);
+  EXPECT_TRUE(tree.HasErrors());
+  EXPECT_THAT(
+      tree, MatchParseTreeNodes(
+                {MatchVariableDeclaration(
+                     HasError, MatchVariableInitializer(
+                                   "=", MatchParenExpression(
+                                            HasError, MatchNameReference("foo"),
+                                            MatchParenExpressionEnd()))),
+                 MatchFileEnd()}));
+}
+
 }  // namespace
 }  // namespace Carbon
diff --git a/toolchain/parser/parser_impl.cpp b/toolchain/parser/parser_impl.cpp
index 8aaad3280ea8..b634affb29b8 100644
--- a/toolchain/parser/parser_impl.cpp
+++ b/toolchain/parser/parser_impl.cpp
@@ -347,6 +347,8 @@ auto ParseTree::Parser::FindNextOf(
     } else if (kind.IsOpeningSymbol()) {
       new_position =
           TokenizedBuffer::TokenIterator(tokens_.GetMatchedClosingToken(token));
+      // Advance past the closing token.
+      ++new_position;
     } else {
       ++new_position;
     }