[clang] fd86789 - [clang-format] Don't allow variable decls to have trailing return arrows

[Emilia Dreamer via cfe-commits]

Author: Emilia Dreamer
Date: 2023-04-03T15:54:21+03:00
New Revision: fd86789962964a98157e8159c3d95cdc241942e3

URL: https://github.com/llvm/llvm-project/commit/fd86789962964a98157e8159c3d95cdc241942e3
DIFF: https://github.com/llvm/llvm-project/commit/fd86789962964a98157e8159c3d95cdc241942e3.diff

LOG: [clang-format] Don't allow variable decls to have trailing return arrows

The heuristic for determining if an arrow is a trailing return arrow
looks for the auto keyword, along with parentheses. This isn't
sufficient, since it also triggers on variable declarations with an auto
type, and with an arrow operator.

This patch makes sure a function declaration is being parsed, instead of
any other declaration.

Fixes https://github.com/llvm/llvm-project/issues/61469

Reviewed By: HazardyKnusperkeks, owenpan, MyDeveloperDay

Differential Revision: https://reviews.llvm.org/D147377

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 b1060bde9dedd..5171952dba43c 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1922,7 +1922,7 @@ class AnnotatingParser {
                Style.Language == FormatStyle::LK_Java) {
       Current.setType(TT_LambdaArrow);
     } else if (Current.is(tok::arrow) && AutoFound &&
-               (Line.MustBeDeclaration || Line.InPPDirective) &&
+               (Line.MightBeFunctionDecl || Line.InPPDirective) &&
                Current.NestingLevel == 0 &&
                !Current.Previous->isOneOf(tok::kw_operator, tok::identifier)) {
       // not auto operator->() -> xxx;

diff  --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 19b1d96f75ab2..dc2fd4d10c76c 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -1477,6 +1477,72 @@ TEST_F(TokenAnnotatorTest, UnderstandsC11GenericSelection) {
   EXPECT_TOKEN(Tokens[9], tok::colon, TT_GenericSelectionColon);
 }
 
+TEST_F(TokenAnnotatorTest, UnderstandsTrailingReturnArrow) {
+  auto Tokens = annotate("auto f() -> int;");
+  ASSERT_EQ(Tokens.size(), 8u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("auto operator->() -> int;");
+  ASSERT_EQ(Tokens.size(), 9u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::arrow, TT_OverloadedOperator);
+  EXPECT_TOKEN(Tokens[5], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("auto operator++(int) -> int;");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[6], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("auto operator=() -> int;");
+  ASSERT_EQ(Tokens.size(), 9u) << Tokens;
+  EXPECT_TOKEN(Tokens[5], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("auto operator=(int) -> int;");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[6], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("auto foo() -> auto { return Val; }");
+  ASSERT_EQ(Tokens.size(), 12u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::arrow, TT_TrailingReturnArrow);
+
+  Tokens = annotate("struct S { auto bar() const -> int; };");
+  ASSERT_EQ(Tokens.size(), 14u) << Tokens;
+  EXPECT_TOKEN(Tokens[8], tok::arrow, TT_TrailingReturnArrow);
+
+  // Not trailing return arrows
+  Tokens = annotate("auto a = b->c;");
+  ASSERT_EQ(Tokens.size(), 8u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("auto a = (b)->c;");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[6], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("auto a = b()->c;");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[6], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("auto a = b->c();");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("decltype(auto) a = b()->c;");
+  ASSERT_EQ(Tokens.size(), 13u) << Tokens;
+  EXPECT_TOKEN(Tokens[9], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("void f() { auto a = b->c(); }");
+  ASSERT_EQ(Tokens.size(), 16u) << Tokens;
+  EXPECT_TOKEN(Tokens[9], tok::arrow, TT_Unknown);
+
+  Tokens = annotate("void f() { auto a = b()->c; }");
+  ASSERT_EQ(Tokens.size(), 16u) << Tokens;
+  EXPECT_TOKEN(Tokens[11], tok::arrow, TT_Unknown);
+
+  // Mixed
+  Tokens = annotate("auto f() -> int { auto a = b()->c; }");
+  ASSERT_EQ(Tokens.size(), 18u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::arrow, TT_TrailingReturnArrow);
+  EXPECT_TOKEN(Tokens[13], tok::arrow, TT_Unknown);
+}
+
 TEST_F(TokenAnnotatorTest, UnderstandsVerilogOperators) {
   auto Annotate = [this](llvm::StringRef Code) {
     return annotate(Code, getLLVMStyle(FormatStyle::LK_Verilog));