[Clang] prevent crash on unterminated __has_embed

[a-tarasyuk]

Fixes #162953

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This PR addresses the issue of Clang crashing on unterminated __has_embed by guarding all DiscardUntilEndOfDirective paths with the contextual end token and diagnosing the missing ) before reporting unknown parameters.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Oleksandr T. (a-tarasyuk)

Changes

Fixes #162953

---

This PR addresses the issue of Clang crashing on unterminated __has_embed by guarding all DiscardUntilEndOfDirective paths with the contextual end token and diagnosing the missing ) before reporting unknown parameters.

---

Full diff: https://github.com/llvm/llvm-project/pull/163107.diff

4 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/Lex/PPDirectives.cpp (+4-4)
• (modified) clang/lib/Lex/PPMacroExpansion.cpp (+4-6)
• (modified) clang/test/Preprocessor/embed___has_embed_parsing_errors.c (+7)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 65b086caf3652..7e65ba74dc6fd 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -405,6 +405,7 @@ Bug Fixes in This Version
   a function without arguments caused us to try to access a non-existent argument.
   (#GH159080)
 - Fixed a failed assertion with empty filename arguments in ``__has_embed``. (#GH159898)
+- Fixed a crash triggered by unterminated ``__has_embed``. (#GH162953)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 360593d0f33df..67906ca0f461a 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -3648,14 +3648,14 @@ Preprocessor::LexEmbedParameters(Token &CurTok, bool ForHasEmbed) {
           std::pair<tok::TokenKind, SourceLocation> Matches) {
         Diag(CurTok, diag::err_expected) << Expected;
         Diag(Matches.second, diag::note_matching) << Matches.first;
-        if (CurTok.isNot(tok::eod))
+        if (CurTok.isNot(EndTokenKind))
           DiscardUntilEndOfDirective(CurTok);
       };
 
   auto ExpectOrDiagAndSkipToEOD = [&](tok::TokenKind Kind) {
     if (CurTok.isNot(Kind)) {
       Diag(CurTok, diag::err_expected) << Kind;
-      if (CurTok.isNot(tok::eod))
+      if (CurTok.isNot(EndTokenKind))
         DiscardUntilEndOfDirective(CurTok);
       return false;
     }
@@ -3746,7 +3746,7 @@ Preprocessor::LexEmbedParameters(Token &CurTok, bool ForHasEmbed) {
       if (Result.isNegative()) {
         Diag(CurTok, diag::err_requires_positive_value)
             << toString(Result, 10) << /*positive*/ 0;
-        if (CurTok.isNot(tok::eod))
+        if (CurTok.isNot(EndTokenKind))
           DiscardUntilEndOfDirective(CurTok);
         return std::nullopt;
       }
@@ -3889,7 +3889,7 @@ Preprocessor::LexEmbedParameters(Token &CurTok, bool ForHasEmbed) {
       }
       if (!ForHasEmbed) {
         Diag(ParamStartLoc, diag::err_pp_unknown_parameter) << 1 << Parameter;
-        if (CurTok.isNot(tok::eod))
+        if (CurTok.isNot(EndTokenKind))
           DiscardUntilEndOfDirective(CurTok);
         return std::nullopt;
       }
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index dec1956ea0f9a..dd80ae586a1f6 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1262,16 +1262,11 @@ EmbedResult Preprocessor::EvaluateHasEmbed(Token &Tok, IdentifierInfo *II) {
 
   std::optional<LexEmbedParametersResult> Params =
       this->LexEmbedParameters(Tok, /*ForHasEmbed=*/true);
-  assert((Params || Tok.is(tok::eod)) &&
-         "expected success or to be at the end of the directive");
 
   if (!Params)
     return EmbedResult::Invalid;
 
-  if (Params->UnrecognizedParams > 0)
-    return EmbedResult::NotFound;
-
-  if (!Tok.is(tok::r_paren)) {
+  if (Tok.isNot(tok::r_paren)) {
     Diag(this->getLocForEndOfToken(FilenameLoc), diag::err_pp_expected_after)
         << II << tok::r_paren;
     Diag(LParenLoc, diag::note_matching) << tok::l_paren;
@@ -1280,6 +1275,9 @@ EmbedResult Preprocessor::EvaluateHasEmbed(Token &Tok, IdentifierInfo *II) {
     return EmbedResult::Invalid;
   }
 
+  if (Params->UnrecognizedParams > 0)
+    return EmbedResult::NotFound;
+
   SmallString<128> FilenameBuffer;
   StringRef Filename = this->getSpelling(FilenameTok, FilenameBuffer);
   if (Filename.empty())
diff --git a/clang/test/Preprocessor/embed___has_embed_parsing_errors.c b/clang/test/Preprocessor/embed___has_embed_parsing_errors.c
index 9c512a4882e2d..a389fa257b164 100644
--- a/clang/test/Preprocessor/embed___has_embed_parsing_errors.c
+++ b/clang/test/Preprocessor/embed___has_embed_parsing_errors.c
@@ -250,3 +250,10 @@
 
 #if __has_embed("") // expected-error {{empty filename}}
 #endif
+
+// expected-error@+4 {{missing ')' after '__has_embed'}} \
+   expected-error@+4 {{expected value in expression}} \
+   expected-error@+4 {{unterminated conditional directive}} \
+   expected-note@+4 {{to match this '('}}
+#if __has_embed (__FILE__ limit(1) foo
+int a = __has_embed (__FILE__);

[Fznamznon]

A test NIT, otherwise LGTM

[AaronBallman]

LGTM!