[Clang] Fix the location of default init expressions

[cor3ntin]

Summary

Default member initializations constructed from
a parenthesized aggregate initialization should be constructed
at the location of the left paren, to be consistent with
brace initialization.
Otherwise we get diagmostics and source_location in the wrong places.

Fixes #63903

[aaron.ballman]

Should this come with a release note or is it correcting functionality added for this release?

clang/test/SemaCXX/source_location.cpp

796

Shouldn't this test fail because i != j?

Can you add a test that demonstrates we've corrected the source location information for diagnostics?

[cor3ntin]

clang/test/SemaCXX/source_location.cpp

796

They should all be equal!

Can you add a test that demonstrates we've corrected the source location information for diagnostics?

Hum, i was planning to do that in https://reviews.llvm.org/D155175. I can try to think of something there!

[aaron.ballman]

clang/test/SemaCXX/source_location.cpp

796

They should all be equal!

Whaaaaa? Shouldn't i == 790 && j == 791?

[cor3ntin]

Address Aaron's comments

[tbaeder]

clang/test/SemaCXX/source_location.cpp

796

IIUC, they are evaluated as part of the constructor, so the values should be 795 or 796. Maybe that can be changed to

static_assert(S(0).i == S{0}.i == 796);

?

[cor3ntin]

clang/test/SemaCXX/source_location.cpp

796

This is https://cplusplus.github.io/CWG/issues/2631.html

[aaron.ballman]

LGTM

clang/test/SemaCXX/source_location.cpp

796

Oh yeah! Thank you for the reminder, that makes sense now. A comment reminding other readers might not be a bad idea.

clang/docs/ReleaseNotes.rst

 - Fix false postive check for constrained satisfaction in standard C++ modules.
   (`#62589 <https://github.com/llvm/llvm-project/issues/62589>`_)
 - Serialize the evaluated constant values for variable declarations in standard
   C++ modules.
   (`#62796 <https://github.com/llvm/llvm-project/issues/62796>`_)
 - Merge lambdas in require expressions in standard C++ modules.
   (`#63544 <https://github.com/llvm/llvm-project/issues/63544>`_)
 
+- Fix location of default member initialization in parenthesized aggregate
+  initialization.
+  (`#63903 <https://github.com/llvm/llvm-project/issues/63903>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - Preserve ``namespace`` definitions that follow malformed declarations.
 
 Miscellaneous Bug Fixes
 ^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaInit.cpp

for (FieldDecl *FD : RD->fields()) {
       } else {
         // We've processed all of the args, but there are still members that
         // have to be initialized.
         if (FD->hasInClassInitializer()) {
           if (!VerifyOnly) {
             // C++ [dcl.init]p16.6.2.2
             //   The remaining elements are initialized with their default
             //   member initializers, if any
-            ExprResult DIE = S.BuildCXXDefaultInitExpr(FD->getLocation(), FD);
+            ExprResult DIE = S.BuildCXXDefaultInitExpr(
+                Kind.getParenOrBraceRange().getEnd(), FD);
             if (DIE.isInvalid())
               return;
             S.checkInitializerLifetime(SubEntity, DIE.get());
             InitExprs.push_back(DIE.get());
           }
         } else {
           // C++ [dcl.init]p17.6.2.2
           //   The remaining elements...otherwise are value initialzed

clang/test/SemaCXX/paren-list-agg-init.cpp

 }
 
 }
 
 namespace gh63758 {
   struct S {} s;
   auto words = (char[])s; // expected-error {{C-style cast from 'struct S' to 'char[]' is not allowed}}
 };
+
+namespace GH63903 {
+  constexpr int f(); // expected-note {{declared here}}
+  struct S {
+    int a = 0, b = f(); // expected-note {{undefined function 'f' cannot be used in a constant expression}}
+  };
+
+  // Test that errors produced by default members are produced at the location of the initialization
+  constexpr S s(0); // beforecxx20-warning {{aggregate initialization of type 'const S' from a parenthesized list of values is a C++20 extension}} \
+                    // expected-error {{constexpr variable 's' must be initialized by a constant expression}}
+}

clang/test/SemaCXX/source_location.cpp

 // RUN: %clang_cc1 -std=c++1z -fcxx-exceptions -fexceptions -verify %s
 // RUN: %clang_cc1 -std=c++2a -fcxx-exceptions -DUSE_CONSTEVAL -fexceptions -verify %s
+// RUN: %clang_cc1 -std=c++2b -fcxx-exceptions -DUSE_CONSTEVAL -DPAREN_INIT -fexceptions -verify %s
 // RUN: %clang_cc1 -std=c++1z -fcxx-exceptions -fms-extensions -DMS -fexceptions -verify %s
 // RUN: %clang_cc1 -std=c++2a -fcxx-exceptions -fms-extensions -DMS -DUSE_CONSTEVAL -fexceptions -verify %s
 // expected-no-diagnostics
 
 #define assert(...) ((__VA_ARGS__) ? ((void)0) : throw 42)
 #define CURRENT_FROM_MACRO() SL::current()
 #define FORWARD(...) __VA_ARGS__
 

 template <typename T>
 constexpr int f(int i = G<T>{}.line) {
     return i;
 }
 
 static_assert(f<int>() != // intentional new line
               f<int>());
 }
+
+#ifdef PAREN_INIT
+namespace GH63903 {
+struct S {
+    int _;
+    int i = SL::current().line();
+    int j = __builtin_LINE();
+};
+// Ensure parent aggregate initialization is consistent with brace
+// aggregate initialization.
+// Note: consteval functions are evaluated where they are used.
+static_assert(S(0).i == __builtin_LINE());
+static_assert(S(0).i == S{0}.i);
+static_assert(S(0).j == S{0}.j);
+static_assert(S(0).j == S{0}.i);
+}
+#endif