From 14f8425ce62fde83735f9504d9966e628e5b43b8 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sun, 10 Nov 2024 15:27:14 -0800
Subject: [PATCH 01/26] THIS IS JUST A START: First attempt to combine
 information from PR #4953 and PR #5437

---
 .../pybind11/conduit/pybind11_platform_abi_id.h | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index a7733bcf5c..f1179e69a0 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -54,9 +54,7 @@
 #endif
 
 #ifndef PYBIND11_BUILD_ABI
-#    if defined(__GXX_ABI_VERSION) // Linux/OSX.
-#        define PYBIND11_BUILD_ABI "_cxxabi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(__GXX_ABI_VERSION)
-#    elif defined(_MSC_VER)               // See PR #4953.
+#    if defined(_MSC_VER)                 // See PR #4953.
 #        if defined(_MT) && defined(_DLL) // Corresponding to CL command line options /MD or /MDd.
 #            if (_MSC_VER) / 100 == 19
 #                define PYBIND11_BUILD_ABI "_md_mscver19"
@@ -72,8 +70,17 @@
 #                error "Unknown major version for MSC_VER: PLEASE REVISE THIS CODE."
 #            endif
 #        endif
-#    elif defined(__NVCOMPILER)       // NVHPC (PGI-based).
-#        define PYBIND11_BUILD_ABI "" // TODO: What should be here, to prevent UB?
+#    elif defined(__NVCOMPILER)        // NVHPC (PGI-based).
+#        define PYBIND11_BUILD_ABI ""  // TODO: What should be here, to prevent UB?
+#    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
+#        define PYBIND11_BUILD_ABI "_libcpp" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
+#    elif defined(__GXX_ABI_VERSION)
+#        if __GXX_ABI_VERSION >= 1002 && defined(_GLIBCXX_USE_CXX11_ABI)
+#            define PYBIND11_BUILD_ABI                                                            \
+                "_usecxx11" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
+#        else
+#            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
+#        endif
 #    else
 #        error "Unknown platform or compiler: PLEASE REVISE THIS CODE."
 #    endif

From b72c42d489c46db317c23c1af6c1065585cf1996 Mon Sep 17 00:00:00 2001
From: "Marcus D. Hanwell" <marcus@cryos.net>
Date: Wed, 20 Nov 2024 16:37:16 -0500
Subject: [PATCH 02/26] Include GXX_ABI and USE_CXX in the identifier

Further constrain to GXX_ABI 1002 or greater and less than 2000,
hopefully future proof by summarizing that as `1` along with CXX11 on or
off.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index f1179e69a0..30743e1121 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -75,9 +75,9 @@
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_libcpp" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(__GXX_ABI_VERSION)
-#        if __GXX_ABI_VERSION >= 1002 && defined(_GLIBCXX_USE_CXX11_ABI)
+#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000 && defined(_GLIBCXX_USE_CXX11_ABI)
 #            define PYBIND11_BUILD_ABI                                                            \
-                "_usecxx11" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
+                "_gxx_abi_1_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #        else
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif

From 8369fdce4ba1c338bc2d5eb57238e2215dc2905d Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 20 Nov 2024 21:39:53 +0000
Subject: [PATCH 03/26] style: pre-commit fixes

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 30743e1121..54c8097535 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -75,7 +75,8 @@
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_libcpp" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(__GXX_ABI_VERSION)
-#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000 && defined(_GLIBCXX_USE_CXX11_ABI)
+#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000                                 \
+            && defined(_GLIBCXX_USE_CXX11_ABI)
 #            define PYBIND11_BUILD_ABI                                                            \
                 "_gxx_abi_1_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #        else

From 476c322fec2f2136b498229ec75b8f4b7a139bce Mon Sep 17 00:00:00 2001
From: "Marcus D. Hanwell" <marcus@cryos.net>
Date: Wed, 20 Nov 2024 19:44:36 -0500
Subject: [PATCH 04/26] Use `gxx_abi_1xxx` and simplify the Clang string

After discussions with Ralf Grosse-Kunstleve we think these would make
good identifiers that are concise and clear.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 54c8097535..9f173c91d0 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -73,12 +73,12 @@
 #    elif defined(__NVCOMPILER)        // NVHPC (PGI-based).
 #        define PYBIND11_BUILD_ABI ""  // TODO: What should be here, to prevent UB?
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
-#        define PYBIND11_BUILD_ABI "_libcpp" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
+#        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(__GXX_ABI_VERSION)
 #        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000                                 \
             && defined(_GLIBCXX_USE_CXX11_ABI)
 #            define PYBIND11_BUILD_ABI                                                            \
-                "_gxx_abi_1_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
+                "_gxx_abi_1xxx_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #        else
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif

From 271720fde97f72d0c0002619114bd9edea5bc95f Mon Sep 17 00:00:00 2001
From: "Marcus D. Hanwell" <marcus@cryos.net>
Date: Wed, 20 Nov 2024 20:10:08 -0500
Subject: [PATCH 05/26] Error if `_GLIBCXX_USE_CXX11_ABI` is not defined

Within the `__GXX_ABI_VERSION` block this should always be defined,
guard against unexpected defines and make the error obvious.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 9f173c91d0..7e9b801d32 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -75,8 +75,10 @@
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(__GXX_ABI_VERSION)
-#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000                                 \
-            && defined(_GLIBCXX_USE_CXX11_ABI)
+#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000
+#            if !defined(_GLIBCXX_USE_CXX11_ABI)
+#                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined"
+#            endif
 #            define PYBIND11_BUILD_ABI                                                            \
                 "_gxx_abi_1xxx_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #        else

From 28081fc8c8e861477b83cddd145ab32299acf344 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sun, 24 Nov 2024 12:45:11 -0800
Subject: [PATCH 06/26] Change `usecxx11` to `use_cxx11_abi` for correspondence
 with `_GLIBCXX_USE_CXX11_ABI` (similarly to `gxx_abi` for
 `__GXX_ABI_VERSION`).

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 7e9b801d32..d7c0168925 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -77,10 +77,11 @@
 #    elif defined(__GXX_ABI_VERSION)
 #        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000
 #            if !defined(_GLIBCXX_USE_CXX11_ABI)
-#                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined"
+#                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined: PLEASE REVISE THIS CODE."
 #            endif
 #            define PYBIND11_BUILD_ABI                                                            \
-                "_gxx_abi_1xxx_usecxx11_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
+                "_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(                 \
+                    _GLIBCXX_USE_CXX11_ABI)
 #        else
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif

From fe2dbcbb59a16554ad0c40cceb3f85f63282a274 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sun, 24 Nov 2024 13:05:16 -0800
Subject: [PATCH 07/26] `PYBIND11_COMPILER_TYPE` overhaul, mainly: replace
 `_icc`, `_clang`, `_gcc` with `_system`

---
 .../conduit/pybind11_platform_abi_id.h        | 20 ++++++++-----------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index d7c0168925..1481d6e4d2 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,22 +23,18 @@
 // A user can manually set this string if they know their
 // compiler is compatible.
 #ifndef PYBIND11_COMPILER_TYPE
-#    if defined(_MSC_VER)
-#        define PYBIND11_COMPILER_TYPE "_msvc"
-#    elif defined(__INTEL_COMPILER)
-#        define PYBIND11_COMPILER_TYPE "_icc"
-#    elif defined(__clang__)
-#        define PYBIND11_COMPILER_TYPE "_clang"
-#    elif defined(__PGI)
-#        define PYBIND11_COMPILER_TYPE "_pgi"
-#    elif defined(__MINGW32__)
+#    if defined(__MINGW32__)
 #        define PYBIND11_COMPILER_TYPE "_mingw"
 #    elif defined(__CYGWIN__)
 #        define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
-#    elif defined(__GNUC__)
-#        define PYBIND11_COMPILER_TYPE "_gcc"
+#    elif defined(_MSC_VER)
+#        define PYBIND11_COMPILER_TYPE "_msvc"
+#    elif defined(__PGI)
+#        define PYBIND11_COMPILER_TYPE "_pgi"
+#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
+#        define PYBIND11_COMPILER_TYPE "_system" // Assumed compatible with system compiler.
 #    else
-#        define PYBIND11_COMPILER_TYPE "_unknown"
+#        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif
 #endif
 

From 9fc951588594c48d4bfd440cd985ffee7be57ae4 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Mon, 25 Nov 2024 11:33:41 -0800
Subject: [PATCH 08/26] Add NVHPC (__PGI) to the list of compilers compatible
 with system compiler.

See comment by @robertmaynard: https://github.com/pybind/pybind11/pull/5439#issuecomment-2498839010
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 1481d6e4d2..d1f22329ad 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -29,9 +29,7 @@
 #        define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "_msvc"
-#    elif defined(__PGI)
-#        define PYBIND11_COMPILER_TYPE "_pgi"
-#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
+#    elif defined(__INTEL_COMPILER) || defined(__PGI) || defined(__clang__) || defined(__GNUC__)
 #        define PYBIND11_COMPILER_TYPE "_system" // Assumed compatible with system compiler.
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."

From d412303e727923571bfd9b907809b1d73a045b34 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Mon, 25 Nov 2024 13:24:43 -0800
Subject: [PATCH 09/26] Fix oversight: remove __NVCOMPILER elif branch in
 PYBIND11_BUILD_ABI block.

Also add comment pointing to this PR (#5439).
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index d1f22329ad..f1ab740d62 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -64,11 +64,9 @@
 #                error "Unknown major version for MSC_VER: PLEASE REVISE THIS CODE."
 #            endif
 #        endif
-#    elif defined(__NVCOMPILER)        // NVHPC (PGI-based).
-#        define PYBIND11_BUILD_ABI ""  // TODO: What should be here, to prevent UB?
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
-#    elif defined(__GXX_ABI_VERSION)
+#    elif defined(__GXX_ABI_VERSION) // See PR #5439.
 #        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000
 #            if !defined(_GLIBCXX_USE_CXX11_ABI)
 #                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined: PLEASE REVISE THIS CODE."

From b6ccce35e69f1f14da4ed7116c79a2ce43c019b2 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 26 Nov 2024 00:07:02 -0800
Subject: [PATCH 10/26] Revert "Fix oversight: remove __NVCOMPILER elif branch
 in PYBIND11_BUILD_ABI block."

This reverts commit d412303e727923571bfd9b907809b1d73a045b34.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index f1ab740d62..d1f22329ad 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -64,9 +64,11 @@
 #                error "Unknown major version for MSC_VER: PLEASE REVISE THIS CODE."
 #            endif
 #        endif
+#    elif defined(__NVCOMPILER)        // NVHPC (PGI-based).
+#        define PYBIND11_BUILD_ABI ""  // TODO: What should be here, to prevent UB?
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
-#    elif defined(__GXX_ABI_VERSION) // See PR #5439.
+#    elif defined(__GXX_ABI_VERSION)
 #        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000
 #            if !defined(_GLIBCXX_USE_CXX11_ABI)
 #                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined: PLEASE REVISE THIS CODE."

From a58439866de86b14544bbb37ee159028742ca40c Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 26 Nov 2024 00:07:06 -0800
Subject: [PATCH 11/26] Revert "Add NVHPC (__PGI) to the list of compilers
 compatible with system compiler."

This reverts commit 9fc951588594c48d4bfd440cd985ffee7be57ae4.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index d1f22329ad..1481d6e4d2 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -29,7 +29,9 @@
 #        define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "_msvc"
-#    elif defined(__INTEL_COMPILER) || defined(__PGI) || defined(__clang__) || defined(__GNUC__)
+#    elif defined(__PGI)
+#        define PYBIND11_COMPILER_TYPE "_pgi"
+#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
 #        define PYBIND11_COMPILER_TYPE "_system" // Assumed compatible with system compiler.
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."

From 23a5f2b6f8e3762a3993b52933a44029c8f5dbba Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 26 Nov 2024 00:22:43 -0800
Subject: [PATCH 12/26] Define NVHPC PYBIND11_BUILD_ABI using __GNUC__,
 __GNUC_MINOR__, _GLIBCXX_USE_CXX11_ABI

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 1481d6e4d2..f108192d51 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -66,8 +66,10 @@
 #                error "Unknown major version for MSC_VER: PLEASE REVISE THIS CODE."
 #            endif
 #        endif
-#    elif defined(__NVCOMPILER)        // NVHPC (PGI-based).
-#        define PYBIND11_BUILD_ABI ""  // TODO: What should be here, to prevent UB?
+#    elif defined(__NVCOMPILER) // NVHPC (PGI-based).
+#        define PYBIND11_BUILD_ABI                                                                      \
+            "_gnuc_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(__GNUC__) "_" PYBIND11_PLATFORM_ABI_ID_TOSTRING( \
+                __GNUC_MINOR__) "_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(__GXX_ABI_VERSION)

From 8fa10bfd2bfccd928e9432a88997afdf7af14e19 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 26 Nov 2024 13:08:50 -0800
Subject: [PATCH 13/26] Use _GLIBCXX_USE_CXX11_ABI to detect libstdc++, then
 assume that NVHPC is always in the 1xxx ABI family.

---
 .../conduit/pybind11_platform_abi_id.h        | 22 ++++++-------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index f108192d51..e5f83d155c 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -29,8 +29,6 @@
 #        define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "_msvc"
-#    elif defined(__PGI)
-#        define PYBIND11_COMPILER_TYPE "_pgi"
 #    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
 #        define PYBIND11_COMPILER_TYPE "_system" // Assumed compatible with system compiler.
 #    else
@@ -66,23 +64,17 @@
 #                error "Unknown major version for MSC_VER: PLEASE REVISE THIS CODE."
 #            endif
 #        endif
-#    elif defined(__NVCOMPILER) // NVHPC (PGI-based).
-#        define PYBIND11_BUILD_ABI                                                                      \
-            "_gnuc_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(__GNUC__) "_" PYBIND11_PLATFORM_ABI_ID_TOSTRING( \
-                __GNUC_MINOR__) "_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_GLIBCXX_USE_CXX11_ABI)
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
-#    elif defined(__GXX_ABI_VERSION)
-#        if __GXX_ABI_VERSION >= 1002 && __GXX_ABI_VERSION < 2000
-#            if !defined(_GLIBCXX_USE_CXX11_ABI)
-#                error "UNEXPECTED: _GLIBCXX_USE_CXX11_ABI not defined: PLEASE REVISE THIS CODE."
-#            endif
-#            define PYBIND11_BUILD_ABI                                                            \
-                "_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(                 \
-                    _GLIBCXX_USE_CXX11_ABI)
-#        else
+#    elif defined(_GLIBCXX_USE_CXX11_ABI) // See PR #5439.
+#        if defined(__GXX_ABI_VERSION) && __GXX_ABI_VERSION < 1002 || __GXX_ABI_VERSION >= 2000
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif
+//       // Assume NVHPC it is in the 1xxx ABI family. THIS ASSUMPTION IS NOT FUTURE PROOF,
+//       // but on balance the best we can do.
+#        define PYBIND11_BUILD_ABI                                                                \
+            "_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(                     \
+                _GLIBCXX_USE_CXX11_ABI)
 #    else
 #        error "Unknown platform or compiler: PLEASE REVISE THIS CODE."
 #    endif

From 02daf15b74e7b22c563ed77113c1993af59b3cb8 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 26 Nov 2024 14:40:21 -0800
Subject: [PATCH 14/26] Enhance NVHPC comment and limited future proofing.

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index e5f83d155c..af9a68ff01 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -67,11 +67,17 @@
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
 #        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(_GLIBCXX_USE_CXX11_ABI) // See PR #5439.
+#        if defined(__NVCOMPILER)
+//           // Assume that NVHPC is in the 1xxx ABI family.
+//           // THIS ASSUMPTION IS NOT FUTURE PROOF but apparently the best we can do.
+//           // Please let us know if there is a way to validate the assumption here.
+#        elif !defined(__GXX_ABI_VERSION)
+#            error                                                                                \
+                "Unknown platform or compiler (_GLIBCXX_USE_CXX11_ABI): PLEASE REVISE THIS CODE."
+#        endif
 #        if defined(__GXX_ABI_VERSION) && __GXX_ABI_VERSION < 1002 || __GXX_ABI_VERSION >= 2000
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif
-//       // Assume NVHPC it is in the 1xxx ABI family. THIS ASSUMPTION IS NOT FUTURE PROOF,
-//       // but on balance the best we can do.
 #        define PYBIND11_BUILD_ABI                                                                \
             "_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(                     \
                 _GLIBCXX_USE_CXX11_ABI)

From 3f90808a59a6fdb8a5e6f016f30a2dc257b47b18 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sun, 1 Dec 2024 11:27:28 -0800
Subject: [PATCH 15/26] The `PYBIND11_STDLIB` is obsolete but kept around to
 maintain backward compatibility.

---
 .../pybind11/conduit/pybind11_platform_abi_id.h  | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index af9a68ff01..d3786f5e11 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -36,15 +36,10 @@
 #    endif
 #endif
 
-// Also standard libs
+// PR #5439 made this macro obsolete. However, there are many manipulations of this macro in the
+// wild. Therefore, to maintain backward compatibility, it is kept around.
 #ifndef PYBIND11_STDLIB
-#    if defined(_LIBCPP_VERSION)
-#        define PYBIND11_STDLIB "_libcpp"
-#    elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
-#        define PYBIND11_STDLIB "_libstdcpp"
-#    else
-#        define PYBIND11_STDLIB ""
-#    endif
+#    define PYBIND11_STDLIB ""
 #endif
 
 #ifndef PYBIND11_BUILD_ABI
@@ -65,7 +60,8 @@
 #            endif
 #        endif
 #    elif defined(_LIBCPP_ABI_VERSION) // https://libcxx.llvm.org/DesignDocs/ABIVersioning.html
-#        define PYBIND11_BUILD_ABI "_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
+#        define PYBIND11_BUILD_ABI                                                                \
+            "_libcpp_abi" PYBIND11_PLATFORM_ABI_ID_TOSTRING(_LIBCPP_ABI_VERSION)
 #    elif defined(_GLIBCXX_USE_CXX11_ABI) // See PR #5439.
 #        if defined(__NVCOMPILER)
 //           // Assume that NVHPC is in the 1xxx ABI family.
@@ -79,7 +75,7 @@
 #            error "Unknown platform or compiler (__GXX_ABI_VERSION): PLEASE REVISE THIS CODE."
 #        endif
 #        define PYBIND11_BUILD_ABI                                                                \
-            "_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(                     \
+            "_libstdcpp_gxx_abi_1xxx_use_cxx11_abi_" PYBIND11_PLATFORM_ABI_ID_TOSTRING(           \
                 _GLIBCXX_USE_CXX11_ABI)
 #    else
 #        error "Unknown platform or compiler: PLEASE REVISE THIS CODE."

From b47be2d359f57d00b658a71952c9ef6555057c6c Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sun, 1 Dec 2024 11:46:51 -0800
Subject: [PATCH 16/26] Move `PYBIND11_BUILD_TYPE` down in the file, so that
 the order of macro definitions is the same as in the list defining
 `PYBIND11_PLATFORM_ABI_ID`

---
 .../pybind11/conduit/pybind11_platform_abi_id.h   | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index d3786f5e11..267e2db3d1 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -12,13 +12,6 @@
 #define PYBIND11_PLATFORM_ABI_ID_STRINGIFY(x) #x
 #define PYBIND11_PLATFORM_ABI_ID_TOSTRING(x) PYBIND11_PLATFORM_ABI_ID_STRINGIFY(x)
 
-// On MSVC, debug and release builds are not ABI-compatible!
-#if defined(_MSC_VER) && defined(_DEBUG)
-#    define PYBIND11_BUILD_TYPE "_debug"
-#else
-#    define PYBIND11_BUILD_TYPE ""
-#endif
-
 // Let's assume that different compilers are ABI-incompatible.
 // A user can manually set this string if they know their
 // compiler is compatible.
@@ -82,6 +75,14 @@
 #    endif
 #endif
 
+// On MSVC, debug and release builds are not ABI-compatible!
+#if defined(_MSC_VER) && defined(_DEBUG)
+#    define PYBIND11_BUILD_TYPE "_debug"
+#else
+#    define PYBIND11_BUILD_TYPE ""
+#endif
+
+// Obsolete and slated for removal. DO NOT USE!
 #ifndef PYBIND11_INTERNALS_KIND
 #    define PYBIND11_INTERNALS_KIND ""
 #endif

From e071edc7d67596bbd2cc031b0ac84ab4d77b285b Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Mon, 2 Dec 2024 12:38:42 -0800
Subject: [PATCH 17/26] Introduce `PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE`:

This makes it possible to achieve these two goals:

* Avoid the leading underscore in `PYBIND11_PLATFORM_ABI_ID` (see https://github.com/pybind/pybind11/pull/5439#issuecomment-2503762161)

* Maintain backward compatibility for use cases as reported under https://github.com/pybind/pybind11/pull/5439#issuecomment-2510212677

`PYBIND11_INTERNALS_KIND` is removed in this commit to ensure that `PYBIND11_COMPILER_TYPE` is the first element of the `PYBIND11_PLATFORM_ABI_ID`, so that `PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE` can meaningfully be used as a prefix for `PYBIND11_PLATFORM_ABI_ID` in pybind11/detail/internals.h.
---
 .../conduit/pybind11_platform_abi_id.h        | 25 ++++++++-----------
 include/pybind11/detail/internals.h           |  4 +--
 2 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 267e2db3d1..30c47750df 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -12,18 +12,19 @@
 #define PYBIND11_PLATFORM_ABI_ID_STRINGIFY(x) #x
 #define PYBIND11_PLATFORM_ABI_ID_TOSTRING(x) PYBIND11_PLATFORM_ABI_ID_STRINGIFY(x)
 
-// Let's assume that different compilers are ABI-incompatible.
-// A user can manually set this string if they know their
-// compiler is compatible.
-#ifndef PYBIND11_COMPILER_TYPE
+#ifdef PYBIND11_COMPILER_TYPE
+//   // To maintain backward compatibility (see PR #5439).
+#    define PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE ""
+#else
+#    define PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE "_"
 #    if defined(__MINGW32__)
-#        define PYBIND11_COMPILER_TYPE "_mingw"
+#        define PYBIND11_COMPILER_TYPE "mingw"
 #    elif defined(__CYGWIN__)
-#        define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
+#        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
-#        define PYBIND11_COMPILER_TYPE "_msvc"
+#        define PYBIND11_COMPILER_TYPE "msvc"
 #    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
-#        define PYBIND11_COMPILER_TYPE "_system" // Assumed compatible with system compiler.
+#        define PYBIND11_COMPILER_TYPE "system" // Assumed compatible with system compiler.
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif
@@ -82,11 +83,5 @@
 #    define PYBIND11_BUILD_TYPE ""
 #endif
 
-// Obsolete and slated for removal. DO NOT USE!
-#ifndef PYBIND11_INTERNALS_KIND
-#    define PYBIND11_INTERNALS_KIND ""
-#endif
-
 #define PYBIND11_PLATFORM_ABI_ID                                                                  \
-    PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI             \
-        PYBIND11_BUILD_TYPE
+    PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE
diff --git a/include/pybind11/detail/internals.h b/include/pybind11/detail/internals.h
index 278f35bbaa..5fcaf9b9c1 100644
--- a/include/pybind11/detail/internals.h
+++ b/include/pybind11/detail/internals.h
@@ -272,11 +272,11 @@ struct type_info {
 
 #define PYBIND11_INTERNALS_ID                                                                     \
     "__pybind11_internals_v" PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION)                        \
-        PYBIND11_PLATFORM_ABI_ID "__"
+        PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE PYBIND11_PLATFORM_ABI_ID "__"
 
 #define PYBIND11_MODULE_LOCAL_ID                                                                  \
     "__pybind11_module_local_v" PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION)                     \
-        PYBIND11_PLATFORM_ABI_ID "__"
+        PYBIND11_COMPILER_TYPE_LEADING_UNDERSCORE PYBIND11_PLATFORM_ABI_ID "__"
 
 /// Each module locally stores a pointer to the `internals` data. The data
 /// itself is shared among modules with the same `PYBIND11_INTERNALS_ID`.

From ca9e6990deb9a57f21cba0879499600addeadf06 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 3 Dec 2024 10:47:55 -0800
Subject: [PATCH 18/26] Apply suggestion by @isuruf, with revised comments
 (code is as suggested).

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 30c47750df..0c5a26b50c 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,8 +23,14 @@
 #        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "msvc"
-#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
-#        define PYBIND11_COMPILER_TYPE "system" // Assumed compatible with system compiler.
+#    elif defined(__GLIBC__)                                                                      \
+        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
+//       // Compatibility is determined based on libstdc++ or libc++ ABI version (below).
+#        define PYBIND11_COMPILER_TYPE "glibc"
+#    elif defined(__APPLE__)                                                                      \
+        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
+//       // Compatibility is (usually) determined based on libc++ ABI version (below).
+#        define PYBIND11_COMPILER_TYPE "macos"
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif

From 41daaa41fadd03ede9bdd9479c8ddf4d143330bf Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Tue, 3 Dec 2024 11:40:28 -0800
Subject: [PATCH 19/26] Make determination of `PYBIND11_COMPILER_TYPE`
 `"macos"` or `"glibc"` more general.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The main motivation is to resolve these "Manylinux on 🐍 3.13t • GIL" and "Pyodide wheel" failures:

```
/__w/pybind11/pybind11/include/pybind11/conduit/pybind11_platform_abi_id.h:35:10: error: #error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
   35 | #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
      |          ^~~~~
```

(All other CI jobs succeeded.)

Further thought:

Essentially, under Linux and macOS the `PYBIND11_COMPILER_TYPE` is only for informational purposes.
ABI compatibility is determined by the libstdc++ or libc++ ABI version.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 0c5a26b50c..69492b48ce 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,14 +23,10 @@
 #        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "msvc"
-#    elif defined(__GLIBC__)                                                                      \
-        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
-//       // Compatibility is determined based on libstdc++ or libc++ ABI version (below).
-#        define PYBIND11_COMPILER_TYPE "glibc"
-#    elif defined(__APPLE__)                                                                      \
-        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
-//       // Compatibility is (usually) determined based on libc++ ABI version (below).
+#    elif defined(__APPLE__)
 #        define PYBIND11_COMPILER_TYPE "macos"
+#    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
+#        define PYBIND11_COMPILER_TYPE "glibc"
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif

From e34dc8b511d9f4dba0d128f9cf043f23fd155894 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 5 Dec 2024 16:13:38 -0800
Subject: [PATCH 20/26] Add `PYBIND11_COMPILER_TYPE` `emscripten`

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 69492b48ce..35524d9d89 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -25,6 +25,8 @@
 #        define PYBIND11_COMPILER_TYPE "msvc"
 #    elif defined(__APPLE__)
 #        define PYBIND11_COMPILER_TYPE "macos"
+#    elif defined(__EMSCRIPTEN__)
+#        define PYBIND11_COMPILER_TYPE "emscripten"
 #    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
 #        define PYBIND11_COMPILER_TYPE "glibc"
 #    else

From 75da5fbfd95cb6f431123a92d9fb5885e6c71fc2 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 5 Dec 2024 16:53:57 -0800
Subject: [PATCH 21/26] Add `PYBIND11_COMPILER_TYPE` `graalvm`

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 35524d9d89..6b5ad3fdfd 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -27,6 +27,8 @@
 #        define PYBIND11_COMPILER_TYPE "macos"
 #    elif defined(__EMSCRIPTEN__)
 #        define PYBIND11_COMPILER_TYPE "emscripten"
+#    elif defined(GRAALVM_PYTHON)
+#        define PYBIND11_COMPILER_TYPE "graalvm"
 #    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
 #        define PYBIND11_COMPILER_TYPE "glibc"
 #    else

From fb38f03e8516fa0ebef627b6367af21ca20e57f8 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 12 Dec 2024 06:56:32 -0800
Subject: [PATCH 22/26] Revert "Add `PYBIND11_COMPILER_TYPE` `graalvm`"

This reverts commit 75da5fbfd95cb6f431123a92d9fb5885e6c71fc2.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 6b5ad3fdfd..35524d9d89 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -27,8 +27,6 @@
 #        define PYBIND11_COMPILER_TYPE "macos"
 #    elif defined(__EMSCRIPTEN__)
 #        define PYBIND11_COMPILER_TYPE "emscripten"
-#    elif defined(GRAALVM_PYTHON)
-#        define PYBIND11_COMPILER_TYPE "graalvm"
 #    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
 #        define PYBIND11_COMPILER_TYPE "glibc"
 #    else

From 09131c5dc89b35409b56d6922e8ac18e897bd1d3 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 12 Dec 2024 06:56:36 -0800
Subject: [PATCH 23/26] Revert "Add `PYBIND11_COMPILER_TYPE` `emscripten`"

This reverts commit e34dc8b511d9f4dba0d128f9cf043f23fd155894.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 35524d9d89..69492b48ce 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -25,8 +25,6 @@
 #        define PYBIND11_COMPILER_TYPE "msvc"
 #    elif defined(__APPLE__)
 #        define PYBIND11_COMPILER_TYPE "macos"
-#    elif defined(__EMSCRIPTEN__)
-#        define PYBIND11_COMPILER_TYPE "emscripten"
 #    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
 #        define PYBIND11_COMPILER_TYPE "glibc"
 #    else

From d05ea53990dc6d3ced57f916230d8763a6dfbceb Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 12 Dec 2024 06:56:37 -0800
Subject: [PATCH 24/26] Revert "Make determination of `PYBIND11_COMPILER_TYPE`
 `"macos"` or `"glibc"` more general."

This reverts commit 41daaa41fadd03ede9bdd9479c8ddf4d143330bf.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 69492b48ce..0c5a26b50c 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,10 +23,14 @@
 #        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "msvc"
-#    elif defined(__APPLE__)
-#        define PYBIND11_COMPILER_TYPE "macos"
-#    elif defined(__GLIBC__) || defined(_GLIBCXX_USE_CXX11_ABI)
+#    elif defined(__GLIBC__)                                                                      \
+        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
+//       // Compatibility is determined based on libstdc++ or libc++ ABI version (below).
 #        define PYBIND11_COMPILER_TYPE "glibc"
+#    elif defined(__APPLE__)                                                                      \
+        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
+//       // Compatibility is (usually) determined based on libc++ ABI version (below).
+#        define PYBIND11_COMPILER_TYPE "macos"
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif

From 776d1635c6c5d74e13b621d7f49a12b40d9ac9bc Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 12 Dec 2024 06:56:38 -0800
Subject: [PATCH 25/26] Revert "Apply suggestion by @isuruf, with revised
 comments (code is as suggested)."

This reverts commit ca9e6990deb9a57f21cba0879499600addeadf06.
---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 0c5a26b50c..30c47750df 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,14 +23,8 @@
 #        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "msvc"
-#    elif defined(__GLIBC__)                                                                      \
-        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
-//       // Compatibility is determined based on libstdc++ or libc++ ABI version (below).
-#        define PYBIND11_COMPILER_TYPE "glibc"
-#    elif defined(__APPLE__)                                                                      \
-        && (defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__))
-//       // Compatibility is (usually) determined based on libc++ ABI version (below).
-#        define PYBIND11_COMPILER_TYPE "macos"
+#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
+#        define PYBIND11_COMPILER_TYPE "system" // Assumed compatible with system compiler.
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."
 #    endif

From 738b7ec16f5fdb6220c93da73090fad5b009ce98 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Thu, 19 Dec 2024 12:36:35 -0800
Subject: [PATCH 26/26] Remove `defined(__INTEL_COMPILER)` as suggested by
 @hpkfft under
 https://github.com/pybind/pybind11/pull/5439#discussion_r1889156543

---
 include/pybind11/conduit/pybind11_platform_abi_id.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/pybind11/conduit/pybind11_platform_abi_id.h b/include/pybind11/conduit/pybind11_platform_abi_id.h
index 30c47750df..d21fdc56d8 100644
--- a/include/pybind11/conduit/pybind11_platform_abi_id.h
+++ b/include/pybind11/conduit/pybind11_platform_abi_id.h
@@ -23,7 +23,7 @@
 #        define PYBIND11_COMPILER_TYPE "gcc_cygwin"
 #    elif defined(_MSC_VER)
 #        define PYBIND11_COMPILER_TYPE "msvc"
-#    elif defined(__INTEL_COMPILER) || defined(__clang__) || defined(__GNUC__)
+#    elif defined(__clang__) || defined(__GNUC__)
 #        define PYBIND11_COMPILER_TYPE "system" // Assumed compatible with system compiler.
 #    else
 #        error "Unknown PYBIND11_COMPILER_TYPE: PLEASE REVISE THIS CODE."