On 1/6/25 7:21 AM, Nathaniel Shead wrote:
This fixes an issue where lambdas declared in the initializer of a
static data member within the class body do not get a mangling scope of
that variable; this results in mangled names that do not conform to the
ABI spec.

To do this, the patch splits up grokfield for this case specifically,
allowing a declaration to be build and used in start_lambda_scope before
parsing the initializer, so that record_lambda_scope works correctly.

As a drive-by, this also fixes the issue of a static member not being
visible within its own initializer.

OK.

        PR c++/107741

gcc/c-family/ChangeLog:

        * c-opts.cc (c_common_post_options): Bump ABI version.

gcc/ChangeLog:

        * common.opt: Add -fabi-version=20.
        * doc/invoke.texi: Likewise.

gcc/cp/ChangeLog:

        * cp-tree.h (start_initialized_static_member): Declare.
        (finish_initialized_static_member): Declare.
        * decl2.cc (start_initialized_static_member): New function.
        (finish_initialized_static_member): New function.
        * lambda.cc (record_lambda_scope): Support falling back to old
        ABI (maybe with warning).
        * parser.cc (cp_parser_member_declaration): Build decl early
        when parsing an initialized static data member.

gcc/testsuite/ChangeLog:

        * g++.dg/abi/macro0.C: Bump ABI version.
        * g++.dg/abi/mangle74.C: Remove XFAILs.
        * g++.dg/other/fold1.C: Restore originally raised error.
        * g++.dg/abi/lambda-ctx2-19.C: New test.
        * g++.dg/abi/lambda-ctx2-19vs20.C: New test.
        * g++.dg/abi/lambda-ctx2-20.C: New test.
        * g++.dg/abi/lambda-ctx2.h: New test.
        * g++.dg/cpp0x/static-member-init-1.C: New test.

Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
  gcc/c-family/c-opts.cc                        |  2 +-
  gcc/common.opt                                |  5 +-
  gcc/cp/cp-tree.h                              |  3 +
  gcc/cp/decl2.cc                               | 77 +++++++++++++++++++
  gcc/cp/lambda.cc                              | 33 ++++++--
  gcc/cp/parser.cc                              | 74 ++++++++++++------
  gcc/doc/invoke.texi                           |  3 +
  gcc/testsuite/g++.dg/abi/lambda-ctx2-19.C     | 10 +++
  gcc/testsuite/g++.dg/abi/lambda-ctx2-19vs20.C |  8 ++
  gcc/testsuite/g++.dg/abi/lambda-ctx2-20.C     | 10 +++
  gcc/testsuite/g++.dg/abi/lambda-ctx2.h        | 27 +++++++
  gcc/testsuite/g++.dg/abi/macro0.C             |  2 +-
  gcc/testsuite/g++.dg/abi/mangle74.C           |  4 +-
  .../g++.dg/cpp0x/static-member-init-1.C       |  5 ++
  gcc/testsuite/g++.dg/other/fold1.C            |  2 +-
  15 files changed, 230 insertions(+), 35 deletions(-)
  create mode 100644 gcc/testsuite/g++.dg/abi/lambda-ctx2-19.C
  create mode 100644 gcc/testsuite/g++.dg/abi/lambda-ctx2-19vs20.C
  create mode 100644 gcc/testsuite/g++.dg/abi/lambda-ctx2-20.C
  create mode 100644 gcc/testsuite/g++.dg/abi/lambda-ctx2.h
  create mode 100644 gcc/testsuite/g++.dg/cpp0x/static-member-init-1.C

diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
index b81d1350b1a..87b231861a6 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -1084,7 +1084,7 @@ c_common_post_options (const char **pfilename)
/* Change flag_abi_version to be the actual current ABI level, for the
       benefit of c_cpp_builtins, and to make comparison simpler.  */
-  const int latest_abi_version = 19;
+  const int latest_abi_version = 20;
    /* Generate compatibility aliases for ABI v13 (8.2) by default.  */
    const int abi_compat_default = 13;
diff --git a/gcc/common.opt b/gcc/common.opt
index e2ac99df1d0..4c2560a0632 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1034,10 +1034,13 @@ Driver Undocumented
  ;     Default in G++ 13.
  ;
  ; 19: Emits ABI tags if needed in structured binding mangled names.
-;     Ignores cv-quals on [[no_unique_object]] members.
+;     Ignores cv-quals on [[no_unique_address]] members.
  ;     Mangles constraints on function templates.
  ;     Default in G++ 14.
  ;
+; 20: Fix mangling of lambdas in static data member initializers.
+;     Default in G++ 15.
+;
  ; Additional positive integers will be assigned as new versions of
  ; the ABI become the default version of the ABI.
  fabi-version=
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 1d741ecedc3..f77a325bdd0 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7224,6 +7224,9 @@ extern tree grokfield (const cp_declarator *, 
cp_decl_specifier_seq *,
                       tree, bool, tree, tree);
  extern tree grokbitfield (const cp_declarator *, cp_decl_specifier_seq *,
                          tree, tree, tree);
+extern tree start_initialized_static_member    (const cp_declarator *,
+                                                cp_decl_specifier_seq *, tree);
+extern void finish_initialized_static_member   (tree, tree, tree);
  extern tree splice_template_attributes                (tree *, tree);
  extern bool any_dependent_type_attributes_p   (tree);
  extern tree cp_reconstruct_complex_type               (tree, tree);
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 869701bceee..5e534935dfd 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -1252,6 +1252,83 @@ grokfield (const cp_declarator *declarator,
    return NULL_TREE;
  }
+/* Like grokfield, but just for the initial grok of an initialized static
+   member.  Used to be able to push the new decl before parsing the
+   initialiser.  */
+
+tree
+start_initialized_static_member (const cp_declarator *declarator,
+                                cp_decl_specifier_seq *declspecs,
+                                tree attrlist)
+{
+  tree value = grokdeclarator (declarator, declspecs, FIELD, SD_INITIALIZED,
+                              &attrlist);
+  if (!value || error_operand_p (value))
+    return error_mark_node;
+  if (TREE_CODE (value) == TYPE_DECL)
+    {
+      error_at (declarator->init_loc,
+               "typedef %qD is initialized (use %qs instead)",
+               value, "decltype");
+      return error_mark_node;
+    }
+  else if (TREE_CODE (value) == FUNCTION_DECL)
+    {
+      if (TREE_CODE (TREE_TYPE (value)) == METHOD_TYPE)
+       error_at (declarator->init_loc,
+                 "invalid initializer for member function %qD",
+                 value);
+      else if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE)
+       error_at (declarator->init_loc,
+                 "initializer specified for static member function %qD",
+                 value);
+      else
+       gcc_unreachable ();
+      return error_mark_node;
+    }
+  else if (TREE_CODE (value) == FIELD_DECL)
+    {
+      /* NSDM marked 'static', grokdeclarator has already errored.  */
+      gcc_checking_assert (seen_error ());
+      return error_mark_node;
+    }
+  gcc_checking_assert (VAR_P (value));
+
+  DECL_CONTEXT (value) = current_class_type;
+  if (processing_template_decl)
+    {
+      value = push_template_decl (value);
+      if (error_operand_p (value))
+       return error_mark_node;
+    }
+
+  if (attrlist)
+    cplus_decl_attributes (&value, attrlist, 0);
+
+  finish_member_declaration (value);
+  DECL_INITIALIZED_IN_CLASS_P (value) = true;
+
+  return value;
+}
+
+/* Finish a declaration prepared with start_initialized_static_member.  */
+
+void
+finish_initialized_static_member (tree decl, tree init, tree asmspec)
+{
+  if (decl == error_mark_node)
+    return;
+  gcc_checking_assert (VAR_P (decl));
+
+  int flags;
+  if (init && DIRECT_LIST_INIT_P (init))
+    flags = LOOKUP_NORMAL;
+  else
+    flags = LOOKUP_IMPLICIT;
+  finish_static_data_member_decl (decl, init, /*init_const_expr_p=*/true,
+                                 asmspec, flags);
+}
+
  /* Like `grokfield', but for bitfields.
     WIDTH is the width of the bitfield, a constant expression.
     The other parameters are as for grokfield.  */
diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc
index be8a0fe01cb..3166f5eab2c 100644
--- a/gcc/cp/lambda.cc
+++ b/gcc/cp/lambda.cc
@@ -32,6 +32,7 @@ along with GCC; see the file COPYING3.  If not see
  #include "gimplify.h"
  #include "target.h"
  #include "decl.h"
+#include "flags.h"
/* Constructor for a lambda expression. */ @@ -1540,13 +1541,35 @@ finish_lambda_scope (void)
  void
  record_lambda_scope (tree lambda)
  {
-  LAMBDA_EXPR_EXTRA_SCOPE (lambda) = lambda_scope.scope;
-  if (lambda_scope.scope)
+  tree closure = LAMBDA_EXPR_CLOSURE (lambda);
+  gcc_checking_assert (closure);
+
+  /* Before ABI v20, lambdas in static data member initializers did not
+     get a dedicated lambda scope.  */
+  tree scope = lambda_scope.scope;
+  if (scope
+      && VAR_P (scope)
+      && DECL_CLASS_SCOPE_P (scope)
+      && DECL_INITIALIZED_IN_CLASS_P (scope))
      {
-      tree closure = LAMBDA_EXPR_CLOSURE (lambda);
-      gcc_checking_assert (closure);
-      maybe_key_decl (lambda_scope.scope, TYPE_NAME (closure));
+      if (!abi_version_at_least (20))
+       scope = NULL_TREE;
+      if (warn_abi && abi_version_crosses (20) && !processing_template_decl)
+       {
+         if (abi_version_at_least (20))
+           warning_at (location_of (closure), OPT_Wabi,
+                       "the mangled name of %qT changed in "
+                       "%<-fabi-version=20%> (GCC 15.1)", closure);
+         else
+           warning_at (location_of (closure), OPT_Wabi,
+                       "the mangled name of %qT changes in "
+                       "%<-fabi-version=20%> (GCC 15.1)", closure);
+       }
      }
+
+  LAMBDA_EXPR_EXTRA_SCOPE (lambda) = scope;
+  if (scope)
+    maybe_key_decl (scope, TYPE_NAME (closure));
  }
// Compare lambda template heads TMPL_A and TMPL_B, used for both
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index f548dc31c2b..dd986444449 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -28737,6 +28737,7 @@ cp_parser_member_declaration (cp_parser* parser)
          tree first_attribute;
          tree initializer;
          bool named_bitfld = false;
+         bool decl_was_initialized_p = false;
/* Peek at the next token. */
          token = cp_lexer_peek_token (parser->lexer);
@@ -28906,9 +28907,8 @@ cp_parser_member_declaration (cp_parser* parser)
                 pure-specifier.  It is not correct to parse the
                 initializer before registering the member declaration
                 since the member declaration should be in scope while
-                its initializer is processed.  However, the rest of the
-                front end does not yet provide an interface that allows
-                us to handle this correctly.  */
+                its initializer is processed.  As such we might build
+                decl pre-emptively.  */
              if (cp_lexer_next_token_is (parser->lexer, CPP_EQ))
                {
                  /* In [class.mem]:
@@ -28935,18 +28935,31 @@ cp_parser_member_declaration (cp_parser* parser)
                    initializer = cp_parser_pure_specifier (parser);
                  else if (decl_specifiers.storage_class != sc_static)
                    initializer = cp_parser_save_nsdmi (parser);
-                 else if (cxx_dialect >= cxx11)
+                 else
                    {
-                     /* Don't require a constant rvalue in C++11, since we
-                        might want a reference constant.  We'll enforce
-                        constancy later.  */
-                     cp_lexer_consume_token (parser->lexer);
-                     /* Parse the initializer.  */
-                     initializer = cp_parser_initializer_clause (parser);
+                     decl = start_initialized_static_member (declarator,
+                                                             &decl_specifiers,
+                                                             attributes);
+                     start_lambda_scope (decl);
+
+                     if (cxx_dialect >= cxx11)
+                       {
+                         /* Don't require a constant rvalue in C++11, since we
+                            might want a reference constant.  We'll enforce
+                            constancy later.  */
+                         cp_lexer_consume_token (parser->lexer);
+                         /* Parse the initializer.  */
+                         initializer = cp_parser_initializer_clause (parser);
+                       }
+                     else
+                       /* Parse the initializer.  */
+                       initializer = cp_parser_constant_initializer (parser);
+
+                     finish_lambda_scope ();
+                     finish_initialized_static_member (decl, initializer,
+                                                       asm_specification);
+                     decl_was_initialized_p = true;
                    }
-                 else
-                   /* Parse the initializer.  */
-                   initializer = cp_parser_constant_initializer (parser);
                }
              else if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_BRACE)
                       && !function_declarator_p (declarator))
@@ -28956,7 +28969,17 @@ cp_parser_member_declaration (cp_parser* parser)
                  if (decl_specifiers.storage_class != sc_static)
                    initializer = cp_parser_save_nsdmi (parser);
                  else
-                   initializer = cp_parser_initializer (parser);
+                   {
+                     decl = start_initialized_static_member (declarator,
+                                                             &decl_specifiers,
+                                                             attributes);
+                     start_lambda_scope (decl);
+                     initializer = cp_parser_initializer (parser);
+                     finish_lambda_scope ();
+                     finish_initialized_static_member (decl, initializer,
+                                                       asm_specification);
+                     decl_was_initialized_p = true;
+                   }
                }
              /* Detect invalid bit-field cases such as
@@ -29031,16 +29054,19 @@ cp_parser_member_declaration (cp_parser* parser)
                  declarator->id_loc = token->location;
/* Create the declaration. */
-             decl = grokfield (declarator, &decl_specifiers,
-                               initializer, /*init_const_expr_p=*/true,
-                               asm_specification, attributes);
-
-             if (parser->fully_implicit_function_template_p)
+             if (!decl_was_initialized_p)
                {
-                 if (friend_p)
-                   finish_fully_implicit_template (parser, 0);
-                 else
-                   decl = finish_fully_implicit_template (parser, decl);
+                 decl = grokfield (declarator, &decl_specifiers,
+                                   initializer, /*init_const_expr_p=*/true,
+                                   asm_specification, attributes);
+
+                 if (parser->fully_implicit_function_template_p)
+                   {
+                     if (friend_p)
+                       finish_fully_implicit_template (parser, 0);
+                     else
+                       decl = finish_fully_implicit_template (parser, decl);
+                   }
                }
            }
@@ -29094,7 +29120,7 @@ cp_parser_member_declaration (cp_parser* parser)
              assume_semicolon = true;
            }
- if (decl)
+         if (decl && !decl_was_initialized_p)
            {
              /* Add DECL to the list of members.  */
              if (!friend_p
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0a7a81b2067..e2e7f29f9ce 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3018,6 +3018,9 @@ that have additional context.
  Version 19, which first appeard in G++ 14, fixes manglings of structured
  bindings to include ABI tags.
+Version 20, which first appeared in G++ 15, fixes manglings of lambdas
+in static data member initializers.
+
  See also @option{-Wabi}.
@opindex fabi-compat-version
diff --git a/gcc/testsuite/g++.dg/abi/lambda-ctx2-19.C 
b/gcc/testsuite/g++.dg/abi/lambda-ctx2-19.C
new file mode 100644
index 00000000000..35d394da8c5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/lambda-ctx2-19.C
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++17 } }
+// { dg-options -fabi-version=19 }
+
+#include "lambda-ctx2.h"
+
+// A and B demangle incorrectly due to static data members missing a lambda 
scope
+// { dg-final { scan-assembler {_ZNK1AUlvE_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1BIiEUlvE2_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1BIiEUlvE3_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1CIiE1xMUlvE_clEv:} } }
diff --git a/gcc/testsuite/g++.dg/abi/lambda-ctx2-19vs20.C 
b/gcc/testsuite/g++.dg/abi/lambda-ctx2-19vs20.C
new file mode 100644
index 00000000000..d4662291e0c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/lambda-ctx2-19vs20.C
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-fabi-version=20 -Wabi=19" }
+
+#include "lambda-ctx2.h"
+
+// { dg-regexp {[^\n]*lambda-ctx2.h:[:0-9]* warning: the mangled name of 
.A::<lambda>.[^\n]*\n} }
+// { dg-regexp {[^\n]*lambda-ctx2.h:[:0-9]* warning: the mangled name of 
.B<int>::<lambda>.[^\n]*\n} }
+// { dg-regexp {[^\n]*lambda-ctx2.h:[:0-9]* warning: the mangled name of 
.B<int>::<lambda>.[^\n]*\n} }
diff --git a/gcc/testsuite/g++.dg/abi/lambda-ctx2-20.C 
b/gcc/testsuite/g++.dg/abi/lambda-ctx2-20.C
new file mode 100644
index 00000000000..764f6061876
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/lambda-ctx2-20.C
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++17 } }
+// { dg-options -fabi-version=20 }
+
+#include "lambda-ctx2.h"
+
+// These correctly associate lambdas in A::x and B::x.
+// { dg-final { scan-assembler {_ZNK1A1xMUlvE_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1BIiE1xMUlvE_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1BIiE1xMUlvE0_clEv:} } }
+// { dg-final { scan-assembler {_ZNK1CIiE1xMUlvE_clEv:} } }
diff --git a/gcc/testsuite/g++.dg/abi/lambda-ctx2.h 
b/gcc/testsuite/g++.dg/abi/lambda-ctx2.h
new file mode 100644
index 00000000000..e359254db90
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/lambda-ctx2.h
@@ -0,0 +1,27 @@
+// PR c++/107741
+
+void side_effect();
+
+struct A {
+  static constexpr auto x = []{ return 1; };
+};
+
+template <typename>
+struct B {
+  static inline auto x = (side_effect(), []{ return 2; }(), []{ return 3; }());
+};
+
+template <typename>
+struct C {
+  static int x;
+};
+
+template <typename T>
+int C<T>::x = (side_effect(), []{ return 4; }());
+
+template int C<int>::x;
+
+int f() {
+  A::x();
+  return B<int>::x;
+}
diff --git a/gcc/testsuite/g++.dg/abi/macro0.C 
b/gcc/testsuite/g++.dg/abi/macro0.C
index 183184e0f0a..f6a57c11ae7 100644
--- a/gcc/testsuite/g++.dg/abi/macro0.C
+++ b/gcc/testsuite/g++.dg/abi/macro0.C
@@ -1,6 +1,6 @@
  // This testcase will need to be kept in sync with c_common_post_options.
  // { dg-options "-fabi-version=0" }
-#if __GXX_ABI_VERSION != 1019
+#if __GXX_ABI_VERSION != 1020
  #error "Incorrect value of __GXX_ABI_VERSION"
  #endif
diff --git a/gcc/testsuite/g++.dg/abi/mangle74.C 
b/gcc/testsuite/g++.dg/abi/mangle74.C
index 7451ce81495..14fe9b9fbf2 100644
--- a/gcc/testsuite/g++.dg/abi/mangle74.C
+++ b/gcc/testsuite/g++.dg/abi/mangle74.C
@@ -26,5 +26,5 @@ int thorn ()
  }
// { dg-final { scan-assembler "_ZNK3varMUlvE_clEv:" } }
-// { dg-final { scan-assembler "_ZNK3Foo3barMUlvE_clEv:" { xfail *-*-* } } }
-// { dg-final { scan-assembler-not "_ZNK3FooUlvE_clEv:" { xfail *-*-* } } }
+// { dg-final { scan-assembler "_ZNK3Foo3barMUlvE_clEv:" } }
+// { dg-final { scan-assembler-not "_ZNK3FooUlvE_clEv:" } }
diff --git a/gcc/testsuite/g++.dg/cpp0x/static-member-init-1.C 
b/gcc/testsuite/g++.dg/cpp0x/static-member-init-1.C
new file mode 100644
index 00000000000..e64e77faade
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/static-member-init-1.C
@@ -0,0 +1,5 @@
+// { dg-do compile { target c++11 } }
+
+struct S {
+    static constexpr const void* x = &x;
+};
diff --git a/gcc/testsuite/g++.dg/other/fold1.C 
b/gcc/testsuite/g++.dg/other/fold1.C
index 8d8df3de68e..d2fc518c220 100644
--- a/gcc/testsuite/g++.dg/other/fold1.C
+++ b/gcc/testsuite/g++.dg/other/fold1.C
@@ -3,6 +3,6 @@
struct A
  {
-    static const int i = i;  // { dg-error "not declared" }
+    static const int i = j;  // { dg-error "not declared" }
      int x[i];              // { dg-error "11:size of array .x. is not an integral 
constant-expression" }
  };

Reply via email to