[clang] [C++26] [Contracts] Initial parser support (PR #221139)

[Chuanqi Xu via cfe-commits]

================
@@ -4244,6 +4222,142 @@ void Parser::ParseTrailingRequiresClause(Declarator &D) {
   }
 }
 
+std::optional<Parser::ContractSpecifierKind>
+Parser::getContractSpecifierKind() {
+  if (!getLangOpts().CPlusPlus || Tok.isNot(tok::identifier))
+    return std::nullopt;
+
+  if (!Ident_pre) {
+    Ident_pre = &PP.getIdentifierTable().get("pre");
+    Ident_post = &PP.getIdentifierTable().get("post");
+  }
+
+  const IdentifierInfo *II = Tok.getIdentifierInfo();
+  if (II == Ident_pre)
+    return ContractSpecifierKind::Pre;
+  if (II == Ident_post)
+    return ContractSpecifierKind::Post;
+  return std::nullopt;
+}
+
+void Parser::ParseContractSpecifiers(Declarator &D) {
+  assert(getContractSpecifierKind() && "expected a contract specifier");
+
+  if (!getLangOpts().CPlusPlus26)
+    Diag(Tok, diag::err_contracts_require_cxx26);
----------------
ChuanqiXu9 wrote:

Yeah, agreed.

https://github.com/llvm/llvm-project/pull/221139