Backport "[clang][analyzer] Fix #embed crash (#107764)"

[steakhal]

Backports the fix for #107724.

(cherry picked from commit d84d955)

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-static-analyzer-1

Author: Balazs Benics (steakhal)

Changes

Backports the fix for #107724.

(cherry picked from commit d84d955)

---

Full diff: https://github.com/llvm/llvm-project/pull/107841.diff

2 Files Affected:

• (modified) clang/lib/StaticAnalyzer/Core/ExprEngine.cpp (+1-4)
• (added) clang/test/Analysis/embed.c (+12)

diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 62a240ecbc6003..c11468a08ae5ca 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1928,6 +1928,7 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::CXXRewrittenBinaryOperatorClass:
     case Stmt::RequiresExprClass:
     case Expr::CXXParenListInitExprClass:
+    case Stmt::EmbedExprClass:
       // Fall through.
 
     // Cases we intentionally don't evaluate, since they don't need
@@ -2430,10 +2431,6 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
       Bldr.addNodes(Dst);
       break;
     }
-
-    case Stmt::EmbedExprClass:
-      llvm::report_fatal_error("Support for EmbedExpr is not implemented.");
-      break;
   }
 }
 
diff --git a/clang/test/Analysis/embed.c b/clang/test/Analysis/embed.c
new file mode 100644
index 00000000000000..32f6c130325740
--- /dev/null
+++ b/clang/test/Analysis/embed.c
@@ -0,0 +1,12 @@
+// RUN: %clang_analyze_cc1 -std=c23 -analyzer-checker=core,debug.ExprInspection -verify %s
+
+void clang_analyzer_dump_ptr(const unsigned char *ptr);
+void clang_analyzer_dump(unsigned char val);
+
+int main() {
+    const unsigned char SelfBytes[] = {
+        #embed "embed.c"
+    };
+    clang_analyzer_dump_ptr(SelfBytes); // expected-warning {{&Element{SelfBytes,0 S64b,unsigned char}}}
+    clang_analyzer_dump(SelfBytes[0]); // expected-warning {{Unknown}} FIXME: This should be the `/` character.
+}

[steakhal]

There is no need to update the release notes as #embed is a new feature, so the crash is not a regression that needs to be highlighted.

[NagyDonat]

LGTM.

[Xazax-hun]

LGTM!

[tru]

Hi, since we are wrapping up LLVM 19.1.0 we are very strict with the fixes we pick at this point. Can you please respond to the following questions to help me understand if this has to be included in the final release or not.

Is this PR a fix for a regression or a critical issue?

What is the risk of accepting this into the release branch?

What is the risk of NOT accepting this into the release branch?

[NagyDonat]

Is this PR a fix for a regression or a critical issue?

#embed support is a new feature introduced in Clang 19, so this is not a regression. However, without this PR Clang Static Analyzer (and clang-tidy which calls Clang Static Analyzer) will crash on any project that contains an #embed directive.

What is the risk of accepting this into the release branch?

Instead of crashing outright, the static analysis will continue after the #embed directive. This could theoretically lead to incorrect analyzer behavior (other crashes, bad analysis results etc.), but there is no reason to expect any issues.

What is the risk of NOT accepting this into the release branch?

Clang Static Analyzer and clang-tidy will crash on code that contain #embed directives.

[github-actions]

@steakhal (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.