[clang] 5ef904b - [clang][ExprConst] Don't try to evaluate value-dependent DeclRefExprs (#67778)

[via cfe-commits]

Author: Timm Baeder
Date: 2023-10-05T08:42:34+02:00
New Revision: 5ef904b5da96562d3209c8f98e1175e623c37bc1

URL: https://github.com/llvm/llvm-project/commit/5ef904b5da96562d3209c8f98e1175e623c37bc1
DIFF: https://github.com/llvm/llvm-project/commit/5ef904b5da96562d3209c8f98e1175e623c37bc1.diff

LOG: [clang][ExprConst] Don't try to evaluate value-dependent DeclRefExprs (#67778)

The Expression here migth be value dependent, which makes us run into an
assertion later on. Just bail out early.

Fixes #67690

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/AST/ExprConstant.cpp
    clang/test/SemaCXX/constant-expression-cxx1z.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 21b76292bca965e..2362e479dfbbc5a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -339,6 +339,9 @@ Bug Fixes in This Version
   (`#64462 <https://github.com/llvm/llvm-project/issues/64462>`_)
 - Fixes a regression where the ``UserDefinedLiteral`` was not properly preserved
   while evaluating consteval functions. (`#63898 <https://github.com/llvm/llvm-project/issues/63898>`_).
+- Fix a crash when evaluating value-dependent structured binding
+  variables at compile time.
+  Fixes (`#67690 <https://github.com/llvm/llvm-project/issues/67690>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

diff  --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index a142ea7c47a4730..d0e27de743604da 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -3357,6 +3357,9 @@ static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
     return false;
   }
 
+  if (E->isValueDependent())
+    return false;
+
   // Dig out the initializer, and use the declaration which it's attached to.
   // FIXME: We should eventually check whether the variable has a reachable
   // initializing declaration.

diff  --git a/clang/test/SemaCXX/constant-expression-cxx1z.cpp b/clang/test/SemaCXX/constant-expression-cxx1z.cpp
index 9335626a5c90a4f..c0766f70cf88158 100644
--- a/clang/test/SemaCXX/constant-expression-cxx1z.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx1z.cpp
@@ -177,3 +177,16 @@ namespace LambdaCallOp {
     p();
   }
 }
+
+// This used to crash due to an assertion failure,
+// see gh#67690
+namespace {
+  struct C {
+    int x;
+  };
+
+  template <const C *p> void f() {
+    const auto &[c] = *p;
+    &c; // expected-warning {{expression result unused}}
+  }
+}