[clang] Fix issues with #embed and intializer lists/template arguments

[Fznamznon]

Sometimes number of expressions in InitListExpr is used for template argument deduction. So, in these cases we need to pay attention to real number of expressions including expanded #embed data.

Fixes #122306

[llvmbot]

@llvm/pr-subscribers-clang

Author: Mariya Podchishchaeva (Fznamznon)

Changes

Sometimes number of expressions in InitListExpr is used for template argument deduction. So, in these cases we need to pay attention to real number of expressions including expanded #embed data.

Fixes #122306

---

Full diff: https://github.com/llvm/llvm-project/pull/128890.diff

5 Files Affected:

• (modified) clang/include/clang/AST/Expr.h (+10)
• (modified) clang/lib/Sema/SemaInit.cpp (+1-1)
• (modified) clang/lib/Sema/SemaOverload.cpp (+7-5)
• (modified) clang/lib/Sema/SemaTemplateDeduction.cpp (+2-1)
• (added) clang/test/SemaCXX/embed-init-list.cpp (+71)

diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 0f98d237dcbcd..cfe49acf20b77 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -5189,6 +5189,16 @@ class InitListExpr : public Expr {
 
   unsigned getNumInits() const { return InitExprs.size(); }
 
+  /// getNumInits but if the list has an EmbedExpr inside includes full length
+  /// of embedded data.
+  unsigned getNumInitsWithEmbedExpanded() const {
+    unsigned Sum = InitExprs.size();
+    for (auto *IE : InitExprs)
+      if (auto *EE = dyn_cast<EmbedExpr>(IE))
+        Sum += EE->getDataElementCount() - 1;
+    return Sum;
+  }
+
   /// Retrieve the set of initializers.
   Expr **getInits() { return reinterpret_cast<Expr **>(InitExprs.data()); }
 
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 340e51adf190d..2387bb4e5b9ae 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -4260,7 +4260,7 @@ static bool TryInitializerListConstruction(Sema &S,
   QualType ArrayType = S.Context.getConstantArrayType(
       E.withConst(),
       llvm::APInt(S.Context.getTypeSize(S.Context.getSizeType()),
-                  List->getNumInits()),
+                  List->getNumInitsWithEmbedExpanded()),
       nullptr, clang::ArraySizeModifier::Normal, 0);
   InitializedEntity HiddenArray =
       InitializedEntity::InitializeTemporary(ArrayType);
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 08586b4908dd4..c344b6fff40c6 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -5710,12 +5710,14 @@ TryListConversion(Sema &S, InitListExpr *From, QualType ToType,
     //    - if the initializer list has one element that is not itself an
     //      initializer list, the implicit conversion sequence is the one
     //      required to convert the element to the parameter type.
+    // Bail out on EmbedExpr as well since we never create EmbedExpr for a
+    // single integer.
     unsigned NumInits = From->getNumInits();
-    if (NumInits == 1 && !isa<InitListExpr>(From->getInit(0)))
-      Result = TryCopyInitialization(S, From->getInit(0), ToType,
-                                     SuppressUserConversions,
-                                     InOverloadResolution,
-                                     AllowObjCWritebackConversion);
+    if (NumInits == 1 && !isa<InitListExpr>(From->getInit(0)) &&
+        !isa<EmbedExpr>(From->getInit(0)))
+      Result = TryCopyInitialization(
+          S, From->getInit(0), ToType, SuppressUserConversions,
+          InOverloadResolution, AllowObjCWritebackConversion);
     //    - if the initializer list has no elements, the implicit conversion
     //      sequence is the identity conversion.
     else if (NumInits == 0) {
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 627cd82ed1c77..dbd73ead8a63f 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -4506,7 +4506,8 @@ static TemplateDeductionResult DeduceFromInitializerList(
       // C++ [temp.deduct.type]p13:
       //   The type of N in the type T[N] is std::size_t.
       QualType T = S.Context.getSizeType();
-      llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
+      llvm::APInt Size(S.Context.getIntWidth(T),
+                       ILE->getNumInitsWithEmbedExpanded());
       if (auto Result = DeduceNonTypeTemplateArgument(
               S, TemplateParams, NTTP, llvm::APSInt(Size), T,
               /*ArrayBound=*/true, Info, /*PartialOrdering=*/false, Deduced,
diff --git a/clang/test/SemaCXX/embed-init-list.cpp b/clang/test/SemaCXX/embed-init-list.cpp
new file mode 100644
index 0000000000000..c511ca707a537
--- /dev/null
+++ b/clang/test/SemaCXX/embed-init-list.cpp
@@ -0,0 +1,71 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-c23-extensions %s
+// expected-no-diagnostics
+
+namespace std {
+typedef decltype(sizeof(int)) size_t;
+
+template <class _E> class initializer_list {
+  const _E *__begin_;
+  size_t __size_;
+
+  constexpr initializer_list(const _E *__b, size_t __s)
+      : __begin_(__b), __size_(__s) {}
+
+public:
+  constexpr initializer_list() : __begin_(nullptr), __size_(0) {}
+};
+} // namespace std
+
+template <typename T> struct S {
+  S(std::initializer_list<T>);
+};
+
+template <> struct S<char> {
+  S(std::initializer_list<char>);
+};
+
+struct S1 {
+  S<char> data;
+  int a;
+};
+
+template <typename _Tp, std::size_t _Nm> void to_array(_Tp (&&__a)[_Nm]) {}
+
+
+template<typename T>
+void tfn(T) {}
+
+void tests() {
+
+  S<char>{{
+#embed __FILE__
+  }};
+
+  S1 ss{std::initializer_list<char>{
+#embed __FILE__
+  }};
+
+  S sss = {
+#embed __FILE__
+  };
+
+  std::initializer_list<int> il{
+#embed __FILE__
+  };
+
+  static constexpr auto initializer_list = std::initializer_list<char>{
+#embed __FILE__
+      , '\0'};
+
+  static constexpr auto intinitializer_list = std::initializer_list<int>{
+#embed __FILE__
+      , '\0'};
+
+  to_array({
+#embed __FILE__
+  });
+
+  tfn<std::initializer_list<int>>({
+#embed __FILE__
+  });
+}

[cor3ntin]

Thanks for the fix!

LGTM but this is missing a changelog entry