[PATCH] D140312: [clang-format] Disallow decltype in the middle of constraints

[Emilia Dreamer via Phabricator via cfe-commits]

rymiel created this revision.
rymiel added reviewers: HazardyKnusperkeks, owenpan, MyDeveloperDay.
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If a function with a `requires` clause as a constraint has a decltype
return type, such as `decltype(auto)`, the decltype was seen to be part
of the constraint clause, rather than as part of the function
declaration, causing it to be placed on the wrong line.

This patch disallows decltype to be a part of these clauses

Fixes https://github.com/llvm/llvm-project/issues/59578


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140312

Files:
  clang/lib/Format/UnwrappedLineParser.cpp
  clang/unittests/Format/FormatTest.cpp
  clang/unittests/Format/TokenAnnotatorTest.cpp


Index: clang/unittests/Format/TokenAnnotatorTest.cpp
===================================================================
--- clang/unittests/Format/TokenAnnotatorTest.cpp
+++ clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -580,6 +580,14 @@
   EXPECT_TRUE(Tokens[9]->ClosesRequiresClause);
   EXPECT_TOKEN(Tokens[11], tok::identifier, TT_FunctionDeclarationName);
 
+  Tokens = annotate("template <typename T>\n"
+                    "requires Bar<T>\n"
+                    "decltype(auto) foo(T) { return false; }");
+  ASSERT_EQ(Tokens.size(), 24u) << Tokens;
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+  EXPECT_TRUE(Tokens[9]->ClosesRequiresClause);
+  EXPECT_TOKEN(Tokens[14], tok::identifier, TT_FunctionDeclarationName);
+
   Tokens = annotate("template <typename T>\n"
                     "struct S {\n"
                     "  void foo() const requires Bar<T>;\n"
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -24199,6 +24199,10 @@
                "  }\n"
                "};");
 
+  verifyFormat("template <class T>\n"
+               "  requires(std::same_as<int, T>)\n"
+               "decltype(auto) fun() {}");
+
   auto Style = getLLVMStyle();
 
   verifyFormat(
Index: clang/lib/Format/UnwrappedLineParser.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineParser.cpp
+++ clang/lib/Format/UnwrappedLineParser.cpp
@@ -3560,7 +3560,6 @@
     case tok::minus:
     case tok::star:
     case tok::slash:
-    case tok::kw_decltype:
       LambdaNextTimeAllowed = true;
       // Just eat them.
       nextToken();


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