[clang] [clang-format] Handle templated elaborated type specifier in function… (PR #77013)

[via cfe-commits]

https://github.com/XDeme updated https://github.com/llvm/llvm-project/pull/77013

>From 45d01cbc7ec958518b1739daa9e9b0dc35c2d194 Mon Sep 17 00:00:00 2001
From: XDeme <fernando.tagawa.gamail.com at gmail.com>
Date: Thu, 4 Jan 2024 19:04:21 -0300
Subject: [PATCH 1/3] [clang-format] Handle templated elaborated type specifier
 in function return type. The behaviour now is consistent with the non
 templated version

---
 clang/lib/Format/UnwrappedLineParser.cpp | 8 ++++++++
 clang/unittests/Format/FormatTest.cpp    | 4 +---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 684609747a5513..aaff6319dd45ef 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -3914,7 +3914,15 @@ void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
   // (this would still leave us with an ambiguity between template function
   // and class declarations).
   if (FormatTok->isOneOf(tok::colon, tok::less)) {
+    int AngleNestingLevel = 0;
     do {
+      if (FormatTok->is(tok::less))
+        ++AngleNestingLevel;
+      else if (FormatTok->is(tok::greater))
+        --AngleNestingLevel;
+
+      if (AngleNestingLevel == 0 && FormatTok->is(tok::r_paren))
+        break;
       if (FormatTok->is(tok::l_brace)) {
         calculateBraceTypes(/*ExpectClassBody=*/true);
         if (!tryToParseBracedList())
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 762fc8254bdfc9..f304407d0ce2f4 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -14583,9 +14583,7 @@ TEST_F(FormatTest, UnderstandContextOfRecordTypeKeywords) {
   verifyFormat("template <> struct X < 15, i<3 && 42 < 50 && 33 < 28> {};");
   verifyFormat("int i = SomeFunction(a<b, a> b);");
 
-  // FIXME:
-  // This now gets parsed incorrectly as class definition.
-  // verifyFormat("class A<int> f() {\n}\nint n;");
+  verifyFormat("class A<int> f() {}\nint n;");
 
   // Elaborate types where incorrectly parsing the structural element would
   // break the indent.

>From 7a7d298c1e25940cc0607ba55eac5677b3b02f46 Mon Sep 17 00:00:00 2001
From: XDeme <fernando.tagawa.gamail.com at gmail.com>
Date: Thu, 4 Jan 2024 21:53:11 -0300
Subject: [PATCH 2/3] Fix edge case in template specialization

---
 clang/lib/Format/UnwrappedLineParser.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index aaff6319dd45ef..dc6ece09059b5d 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -3903,6 +3903,15 @@ void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
       parseParens();
   }
 
+  auto IsTemplate = [&] {
+    FormatToken *Tok = InitialToken.Previous;
+    while (Tok) {
+      if (Tok->is(tok::kw_template))
+        return true;
+      Tok = Tok->Previous;
+    }
+    return false;
+  };
   // Note that parsing away template declarations here leads to incorrectly
   // accepting function declarations as record declarations.
   // In general, we cannot solve this problem. Consider:
@@ -3921,8 +3930,10 @@ void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
       else if (FormatTok->is(tok::greater))
         --AngleNestingLevel;
 
-      if (AngleNestingLevel == 0 && FormatTok->is(tok::r_paren))
+      if (AngleNestingLevel == 0 && !IsTemplate() &&
+          FormatTok->is(tok::r_paren)) {
         break;
+      }
       if (FormatTok->is(tok::l_brace)) {
         calculateBraceTypes(/*ExpectClassBody=*/true);
         if (!tryToParseBracedList())

>From 019992a0e227755015bc46e637d406fee911b9b5 Mon Sep 17 00:00:00 2001
From: XDeme <fernando.tagawa.gamail.com at gmail.com>
Date: Thu, 4 Jan 2024 22:13:15 -0300
Subject: [PATCH 3/3] Add test

---
 clang/unittests/Format/FormatTest.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index f304407d0ce2f4..6ac290b64ca450 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -14584,6 +14584,7 @@ TEST_F(FormatTest, UnderstandContextOfRecordTypeKeywords) {
   verifyFormat("int i = SomeFunction(a<b, a> b);");
 
   verifyFormat("class A<int> f() {}\nint n;");
+  verifyFormat("template <> class Foo<int> F() {\n} n;");
 
   // Elaborate types where incorrectly parsing the structural element would
   // break the indent.