[clang] 17414ea - [clang][Interp] Fix returning nullptr from functions (#67229)

[via cfe-commits]

Author: Timm Baeder
Date: 2023-10-10T11:19:14+02:00
New Revision: 17414eae242b77fe40ce671793bce5fb2e6a3a04

URL: https://github.com/llvm/llvm-project/commit/17414eae242b77fe40ce671793bce5fb2e6a3a04
DIFF: https://github.com/llvm/llvm-project/commit/17414eae242b77fe40ce671793bce5fb2e6a3a04.diff

LOG: [clang][Interp] Fix returning nullptr from functions (#67229)

isLive() is false for null pointers, so we need to special-case this
here.

Added: 
    

Modified: 
    clang/lib/AST/Interp/Interp.h
    clang/test/AST/Interp/functions.cpp

Removed: 
    


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diff  --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
index d62e64bedb213ac..47dc1d08c9c4d8b 100644
--- a/clang/lib/AST/Interp/Interp.h
+++ b/clang/lib/AST/Interp/Interp.h
@@ -214,7 +214,8 @@ bool Ret(InterpState &S, CodePtr &PC, APValue &Result) {
     // FIXME: We could be calling isLive() here, but the emitted diagnostics
     // seem a little weird, at least if the returned expression is of
     // pointer type.
-    if (!Ret.isLive())
+    // Null pointers are considered live here.
+    if (!Ret.isZero() && !Ret.isLive())
       return false;
   }
 

diff  --git a/clang/test/AST/Interp/functions.cpp b/clang/test/AST/Interp/functions.cpp
index 5cdecbff1e9d3d4..68082576f2735e9 100644
--- a/clang/test/AST/Interp/functions.cpp
+++ b/clang/test/AST/Interp/functions.cpp
@@ -343,3 +343,10 @@ namespace TemplateUndefined {
   constexpr int l = consume(0);
   static_assert(l == 0, "");
 }
+
+namespace PtrReturn {
+  constexpr void *a() {
+    return nullptr;
+  }
+  static_assert(a() == nullptr, "");
+}