[clang-format] Recognize "if consteval".

[curdeius]

Summary

Fixes https://github.com/llvm/llvm-project/issues/54140.

[MyDeveloperDay]

LFTM

Do we also need to consider this in the context of "AllowShortIfStatments"? (that would be in a different review in my view)

[JohelEGP]

In D120806#3354119, @MyDeveloperDay wrote:

LFTM

Do we also need to consider this in the context of "AllowShortIfStatments"? (that would be in a different review in my view)

Definitely. Since it didn't work at all, I reported it without a .clang-format. I was hoping it'd play well with AllowShortIfStatments out of the box.
I'm currently building HEAD with this patch to reformat my code.

[curdeius]

I'll handle AllowShortIfStatements and update this review. Should be pretty straightforward.

[JohelEGP]

My few cases format consistently with the condition case:

diff
diff --git a/tests/integration/test.waarudo.io.dynamic.cpp b/tests/integration/test.waarudo.io.dynamic.cpp
index be5a626..e1265b9 100644
--- a/tests/integration/test.waarudo.io.dynamic.cpp
+++ b/tests/integration/test.waarudo.io.dynamic.cpp
@@ -21,7 +21,7 @@ public:
   }
 
   constexpr ~input_source() {
-    if (std::is_constant_evaluated()) {
+    if consteval {
       expects(input_byte == previous_input_byte);
     } else {
       std::ofstream{"test.waarudo.io.dynamic.previous.input.byte.txt"} << "waarudo::byte{'"
@@ -37,7 +37,7 @@ public:
   [[nodiscard]] constexpr waarudo::output_bytes output() override { return {&output_byte, 1z}; }
 
   constexpr ~output_destination() {
-    if (std::is_constant_evaluated()) {
+    if consteval {
       expects(output_byte == previous_output_byte);
     } else {
       std::cout << std::bit_cast<char>(output_byte);
diff --git a/tests/waarudo.test.utilities.cpp b/tests/waarudo.test.utilities.cpp
index ed82b2b..f4ec8e3 100644
--- a/tests/waarudo.test.utilities.cpp
+++ b/tests/waarudo.test.utilities.cpp
@@ -13,7 +13,7 @@ export template<auto F> concept constant_invocable = requires { typename std::in
 export using waarudo::expects;
 
 export constexpr void runtime(void (*const f)()) {
-  if (not std::is_constant_evaluated()) f();
+  if not consteval { f(); }
 }
 
 template<std::integral I, std::invocable<I> F> void visit_values(F f) {

Thank you.

[curdeius]

Great, I'll add a few test cases when landing.

clang/lib/Format/UnwrappedLineParser.cpp

if (FormatTok->is(TT_AttributeMacro))
       nextToken();
     // Handle [[likely]] / [[unlikely]] attributes.
     if (FormatTok->is(tok::l_square) && tryToParseSimpleAttribute())
       parseSquare();
   };
 
   assert(FormatTok->is(tok::kw_if) && "'if' expected");
   nextToken();
+  if (FormatTok->is(tok::exclaim))
+    nextToken();
+  if (FormatTok->is(tok::kw_consteval)) {
+    nextToken();
+  } else {
     if (FormatTok->isOneOf(tok::kw_constexpr, tok::identifier))
       nextToken();
     if (FormatTok->is(tok::l_paren))
       parseParens();
+  }
   HandleAttributes();
 
   bool NeedsUnwrappedLine = false;
   keepAncestorBraces();
 
   FormatToken *IfLeftBrace = nullptr;
   IfStmtKind IfBlockKind = IfStmtKind::NotIf;
 

clang/unittests/Format/FormatTest.cpp

verifyFormat("if constexpr (a)\n"
                "  }\n"
                "g();");
   verifyFormat("if CONSTEXPR (a)\n"
                "  if CONSTEXPR (b) {\n"
                "    f();\n"
                "  }\n"
                "g();");
 
+  verifyFormat("if consteval {\n}");
+  verifyFormat("if !consteval {\n}");
+  verifyFormat("if not consteval {\n}");
+  verifyFormat("if consteval {\n} else {\n}");
+  verifyFormat("if !consteval {\n} else {\n}");
+  verifyFormat("if consteval {\n"
+               "  f();\n"
+               "}");
+  verifyFormat("if !consteval {\n"
+               "  f();\n"
+               "}");
+  verifyFormat("if consteval {\n"
+               "  f();\n"
+               "} else {\n"
+               "  g();\n"
+               "}");
+  verifyFormat("if CONSTEVAL {\n"
+               "  f();\n"
+               "}");
+  verifyFormat("if !CONSTEVAL {\n"
+               "  f();\n"
+               "}");
+
   verifyFormat("if (a)\n"
                "  g();");
   verifyFormat("if (a) {\n"
                "  g()\n"
                "};");
   verifyFormat("if (a)\n"
                "  g();\n"
                "else\n"
TEST_F(FormatTest, FormatShortBracedStatements) {
 
   AllowSimpleBracedStatements.BreakBeforeBraces = FormatStyle::BS_Custom;
   AllowSimpleBracedStatements.BraceWrapping.AfterFunction = true;
   AllowSimpleBracedStatements.BraceWrapping.SplitEmptyRecord = false;
 
   verifyFormat("if (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if constexpr (true) {}", AllowSimpleBracedStatements);
   verifyFormat("if CONSTEXPR (true) {}", AllowSimpleBracedStatements);
+  verifyFormat("if consteval {}", AllowSimpleBracedStatements);
+  verifyFormat("if !consteval {}", AllowSimpleBracedStatements);
+  verifyFormat("if CONSTEVAL {}", AllowSimpleBracedStatements);
   verifyFormat("MYIF (true) {}", AllowSimpleBracedStatements);
   verifyFormat("MYIF constexpr (true) {}", AllowSimpleBracedStatements);
   verifyFormat("MYIF CONSTEXPR (true) {}", AllowSimpleBracedStatements);
   verifyFormat("while (true) {}", AllowSimpleBracedStatements);
   verifyFormat("for (;;) {}", AllowSimpleBracedStatements);
   verifyFormat("if (true) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("if constexpr (true) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("if CONSTEXPR (true) { f(); }", AllowSimpleBracedStatements);
+  verifyFormat("if consteval { f(); }", AllowSimpleBracedStatements);
+  verifyFormat("if CONSTEVAL { f(); }", AllowSimpleBracedStatements);
   verifyFormat("MYIF (true) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("MYIF constexpr (true) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("MYIF CONSTEXPR (true) { f(); }", AllowSimpleBracedStatements);
+  verifyFormat("MYIF consteval { f(); }", AllowSimpleBracedStatements);
+  verifyFormat("MYIF CONSTEVAL { f(); }", AllowSimpleBracedStatements);
   verifyFormat("while (true) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("for (;;) { f(); }", AllowSimpleBracedStatements);
   verifyFormat("if (true) { fffffffffffffffffffffff(); }",
                AllowSimpleBracedStatements);
   verifyFormat("if (true) {\n"
                "  ffffffffffffffffffffffff();\n"
                "}",
                AllowSimpleBracedStatements);