1 files changed, 24 insertions, 19 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 2159a0d..10f0ec3 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -20565,31 +20565,36 @@ void Sema::MarkDeclarationsReferencedInExpr(Expr *E,
 }
 
 /// Emit a diagnostic when statements are reachable.
-/// FIXME: check for reachability even in expressions for which we don't build a
-///        CFG (eg, in the initializer of a global or in a constant expression).
-///        For example,
-///        namespace { auto *p = new double[3][false ? (1, 2) : 3]; }
 bool Sema::DiagIfReachable(SourceLocation Loc, ArrayRef<const Stmt *> Stmts,
                            const PartialDiagnostic &PD) {
-  if (!Stmts.empty() && getCurFunctionOrMethodDecl()) {
-    if (!FunctionScopes.empty())
-      FunctionScopes.back()->PossiblyUnreachableDiags.push_back(
-          sema::PossiblyUnreachableDiag(PD, Loc, Stmts));
-    return true;
-  }
-
+  VarDecl *Decl = ExprEvalContexts.back().DeclForInitializer;
   // The initializer of a constexpr variable or of the first declaration of a
   // static data member is not syntactically a constant evaluated constant,
   // but nonetheless is always required to be a constant expression, so we
   // can skip diagnosing.
-  // FIXME: Using the mangling context here is a hack.
-  if (auto *VD = dyn_cast_or_null<VarDecl>(
-          ExprEvalContexts.back().ManglingContextDecl)) {
-    if (VD->isConstexpr() ||
-        (VD->isStaticDataMember() && VD->isFirstDecl() && !VD->isInline()))
-      return false;
-    // FIXME: For any other kind of variable, we should build a CFG for its
-    // initializer and check whether the context in question is reachable.
+  if (Decl &&
+      (Decl->isConstexpr() || (Decl->isStaticDataMember() &&
+                               Decl->isFirstDecl() && !Decl->isInline())))
+    return false;
+
+  if (Stmts.empty()) {
+    Diag(Loc, PD);
+    return true;
+  }
+
+  if (getCurFunction()) {
+    FunctionScopes.back()->PossiblyUnreachableDiags.push_back(
+        sema::PossiblyUnreachableDiag(PD, Loc, Stmts));
+    return true;
+  }
+
+  // For non-constexpr file-scope variables with reachability context (non-empty
+  // Stmts), build a CFG for the initializer and check whether the context in
+  // question is reachable.
+  if (Decl && Decl->isFileVarDecl()) {
+    AnalysisWarnings.registerVarDeclWarning(
+        Decl, sema::PossiblyUnreachableDiag(PD, Loc, Stmts));
+    return true;
   }
 
   Diag(Loc, PD);