[clang] 0bf63f0 - [clang-format] Disallow trailing return arrows to be operators

[Emilia Dreamer via cfe-commits]

Author: Emilia Dreamer
Date: 2022-09-19T04:04:31+03:00
New Revision: 0bf63f0d1b6b860a7134d668d3a28104c5c9afc1

URL: https://github.com/llvm/llvm-project/commit/0bf63f0d1b6b860a7134d668d3a28104c5c9afc1
DIFF: https://github.com/llvm/llvm-project/commit/0bf63f0d1b6b860a7134d668d3a28104c5c9afc1.diff

LOG: [clang-format] Disallow trailing return arrows to be operators

In the following construction:
`template <typename T> requires Foo<T> || Bar<T> auto func() -> int;`

The `->` of the trailing return type was actually considered as an
operator as part of the binary operation in the requires clause, with
the precedence level of `PrecedenceArrowAndPeriod`, leading to fake
parens being inserted in strange locations, that would never be closed.

Fixes one part of https://github.com/llvm/llvm-project/issues/56213
(the rest will probably be in a separate patch)

Reviewed By: HazardyKnusperkeks, owenpan

Differential Revision: https://reviews.llvm.org/D134049

Added: 
    

Modified: 
    clang/lib/Format/TokenAnnotator.cpp
    clang/unittests/Format/TokenAnnotatorTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index d18adc308efb0..a81bbb99f5d9e 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -2611,8 +2611,10 @@ class ExpressionParser {
       }
       if (Current->is(TT_BinaryOperator) || Current->is(tok::comma))
         return Current->getPrecedence();
-      if (Current->isOneOf(tok::period, tok::arrow))
+      if (Current->isOneOf(tok::period, tok::arrow) &&
+          Current->isNot(TT_TrailingReturnArrow)) {
         return PrecedenceArrowAndPeriod;
+      }
       if ((Style.Language == FormatStyle::LK_Java || Style.isJavaScript()) &&
           Current->isOneOf(Keywords.kw_extends, Keywords.kw_implements,
                            Keywords.kw_throws)) {

diff  --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 1fe8bece722c4..f3007f85e91b0 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -440,6 +440,15 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresClausesAndConcepts) {
   ASSERT_EQ(Tokens.size(), 18u) << Tokens;
   EXPECT_TOKEN(Tokens[11], tok::kw_requires, TT_RequiresClause);
 
+  Tokens = annotate("template <typename T>\n"
+                    "requires Bar<T> || Baz<T>\n"
+                    "auto foo(T) -> int;");
+  ASSERT_EQ(Tokens.size(), 24u) << Tokens;
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+  EXPECT_EQ(Tokens[11]->FakeLParens.size(), 0u);
+  EXPECT_TRUE(Tokens[14]->ClosesRequiresClause);
+  EXPECT_TOKEN(Tokens[20], tok::arrow, TT_TrailingReturnArrow);
+
   Tokens = annotate("template <typename T>\n"
                     "struct S {\n"
                     "  void foo() const requires Bar<T>;\n"