Complete the implementation of P2361 Unevaluated string literals

The attributes changes were left out of Clang 17.
Attributes that used to take a string literal now accept an unevaluated
string literal instead, which means they reject numeric escape sequences
and strings literal with an encoding prefix - but the later was already
ill-formed in most cases.

We need to know that we are going to parse an unevaluated string literal
before we do - so we can reject numeric escape sequence,
so we derive from Attrs.td which attributes parameters are expected
to be string literals.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D156237

1 files changed, 88 insertions, 3 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 2840b48..b5a3ee1 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -288,6 +288,16 @@ static bool attributeHasIdentifierArg(const IdentifierInfo &II) {
 #undef CLANG_ATTR_IDENTIFIER_ARG_LIST
 }
 
+/// Determine whether the given attribute has an identifier argument.
+static ParsedAttributeArgumentsProperties
+attributeStringLiteralListArg(const IdentifierInfo &II) {
+#define CLANG_ATTR_STRING_LITERAL_ARG_LIST
+  return llvm::StringSwitch<uint32_t>(normalizeAttrName(II.getName()))
+#include "clang/Parse/AttrParserStringSwitches.inc"
+      .Default(0);
+#undef CLANG_ATTR_STRING_LITERAL_ARG_LIST
+}
+
 /// Determine whether the given attribute has a variadic identifier argument.
 static bool attributeHasVariadicIdentifierArg(const IdentifierInfo &II) {
 #define CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
@@ -371,6 +381,81 @@ void Parser::ParseAttributeWithTypeArg(IdentifierInfo &AttrName,
                  ScopeName, ScopeLoc, nullptr, 0, Form);
 }
 
+ExprResult
+Parser::ParseUnevaluatedStringInAttribute(const IdentifierInfo &AttrName) {
+  if (Tok.is(tok::l_paren)) {
+    BalancedDelimiterTracker Paren(*this, tok::l_paren);
+    Paren.consumeOpen();
+    ExprResult Res = ParseUnevaluatedStringInAttribute(AttrName);
+    Paren.consumeClose();
+    return Res;
+  }
+  if (!isTokenStringLiteral()) {
+    Diag(Tok.getLocation(), diag::err_expected_string_literal)
+        << /*in attribute...*/ 4 << AttrName.getName();
+    return ExprError();
+  }
+  return ParseUnevaluatedStringLiteralExpression();
+}
+
+bool Parser::ParseAttributeArgumentList(
+    const IdentifierInfo &AttrName, SmallVectorImpl<Expr *> &Exprs,
+    ParsedAttributeArgumentsProperties ArgsProperties) {
+  bool SawError = false;
+  unsigned Arg = 0;
+  while (true) {
+    ExprResult Expr;
+    if (ArgsProperties.isStringLiteralArg(Arg)) {
+      Expr = ParseUnevaluatedStringInAttribute(AttrName);
+    } else if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
+      Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
+      Expr = ParseBraceInitializer();
+    } else {
+      Expr = ParseAssignmentExpression();
+    }
+    Expr = Actions.CorrectDelayedTyposInExpr(Expr);
+
+    if (Tok.is(tok::ellipsis))
+      Expr = Actions.ActOnPackExpansion(Expr.get(), ConsumeToken());
+    else if (Tok.is(tok::code_completion)) {
+      // There's nothing to suggest in here as we parsed a full expression.
+      // Instead fail and propagate the error since caller might have something
+      // the suggest, e.g. signature help in function call. Note that this is
+      // performed before pushing the \p Expr, so that signature help can report
+      // current argument correctly.
+      SawError = true;
+      cutOffParsing();
+      break;
+    }
+
+    if (Expr.isInvalid()) {
+      SawError = true;
+      break;
+    }
+
+    Exprs.push_back(Expr.get());
+
+    if (Tok.isNot(tok::comma))
+      break;
+    // Move to the next argument, remember where the comma was.
+    Token Comma = Tok;
+    ConsumeToken();
+    checkPotentialAngleBracketDelimiter(Comma);
+    Arg++;
+  }
+
+  if (SawError) {
+    // Ensure typos get diagnosed when errors were encountered while parsing the
+    // expression list.
+    for (auto &E : Exprs) {
+      ExprResult Expr = Actions.CorrectDelayedTyposInExpr(E);
+      if (Expr.isUsable())
+        E = Expr.get();
+    }
+  }
+  return SawError;
+}
+
 unsigned Parser::ParseAttributeArgsCommon(
     IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
     ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
@@ -463,9 +548,9 @@ unsigned Parser::ParseAttributeArgsCommon(
                        : Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
       ExprVector ParsedExprs;
-      if (ParseExpressionList(ParsedExprs, llvm::function_ref<void()>(),
-                              /*FailImmediatelyOnInvalidExpr=*/true,
-                              /*EarlyTypoCorrection=*/true)) {
+      ParsedAttributeArgumentsProperties ArgProperties =
+          attributeStringLiteralListArg(*AttrName);
+      if (ParseAttributeArgumentList(*AttrName, ParsedExprs, ArgProperties)) {
         SkipUntil(tok::r_paren, StopAtSemi);
         return 0;
       }