[clang] [C23] Fix failed assertions with invalid #embed parameters (PR #135368)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Aaron Ballman (AaronBallman)

<details>
<summary>Changes</summary>

If the invalid parameter was not the last parameter given, we would fail to skip to the end of the directive and trip a failed assertion.

Fixes #<!-- -->126940

---
Full diff: https://github.com/llvm/llvm-project/pull/135368.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2) 
- (modified) clang/lib/Lex/PPDirectives.cpp (+3-1) 
- (modified) clang/test/Preprocessor/embed_parameter_unrecognized.c (+9-1) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 69c7369755c67..11f62bc881b03 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -170,6 +170,8 @@ C23 Feature Support
   scope.
 - Fixed a bug where you could not cast a null pointer constant to type
   ``nullptr_t``. Fixes #GH133644.
+- Fixed a failed assertion with an invalid parameter to the ``#embed``
+  directive. Fixes #GH126940.
 
 C11 Feature Support
 ^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index d97a6e8d64f9c..dfdba6bd09fd8 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -3897,7 +3897,9 @@ Preprocessor::LexEmbedParameters(Token &CurTok, bool ForHasEmbed) {
           return std::nullopt;
       }
       if (!ForHasEmbed) {
-        Diag(CurTok, diag::err_pp_unknown_parameter) << 1 << Parameter;
+        Diag(ParamStartLoc, diag::err_pp_unknown_parameter) << 1 << Parameter;
+        if (CurTok.isNot(tok::eod))
+          DiscardUntilEndOfDirective(CurTok);
         return std::nullopt;
       }
     }
diff --git a/clang/test/Preprocessor/embed_parameter_unrecognized.c b/clang/test/Preprocessor/embed_parameter_unrecognized.c
index b03384341a00a..c6fef941b7b88 100644
--- a/clang/test/Preprocessor/embed_parameter_unrecognized.c
+++ b/clang/test/Preprocessor/embed_parameter_unrecognized.c
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 %s -std=c23 -E -verify
-// okay-no-diagnostics
 
 #embed __FILE__ unrecognized
 // expected-error at -1 {{unknown embed preprocessor parameter 'unrecognized'}}
@@ -7,3 +6,12 @@
 // expected-error at -1 {{unknown embed preprocessor parameter 'unrecognized::param'}}
 #embed __FILE__ unrecognized::param(with, args)
 // expected-error at -1 {{unknown embed preprocessor parameter 'unrecognized::param'}}
+
+// The first of these two cases was causing a failed assertion due to not being
+// at the end of the directive when we finished skipping past `bla`.
+#embed __FILE__ bla(2) limit(2) // expected-error {{unknown embed preprocessor parameter 'bla'}}
+#embed __FILE__ limit(2) bla(2) // expected-error {{unknown embed preprocessor parameter 'bla'}}
+
+// We intentionally only tell you about one invalid parameter at a time so that
+// we can skip over invalid token soup.
+#embed __FILE__ bla(2) limit(2) bork // expected-error {{unknown embed preprocessor parameter 'bla'}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/135368