Add libXt-1.3.1 build

Makefile

@@ -6,6 +6,7 @@ include mk/config.mk
 include mk/sources.mk
 include mk/common.mk
 include mk/library.mk
+include mk/libxt.mk
 include mk/tests.mk
 include mk/examples.mk
 include mk/upstream-headers.mk

include/X11/ICE/ICElib.h

@@ -0,0 +1,31 @@
+/* Stub X11/ICE/ICElib.h for libx11-compat's libXt build
+ *
+ * Copyright 2026 libx11-compat contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+/* libXt's Shell.c includes this header at the top of the file even when
+ * XT_NO_SM keeps every ICE/SM call out of the compiled translation unit.
+ * Provide an opaque IceConn type plus the small set of helpers and
+ * constants the in-tree compatibility surface references so the header
+ * resolves without dragging libICE into the build closure.
+ */
+#ifndef _LIBX11_COMPAT_ICELIB_H_
+#define _LIBX11_COMPAT_ICELIB_H_
+
+typedef struct _IceConn *IceConn;
+
+/* Real libICE defines IceProcessMessagesStatus as an enum too, but the
+ * values themselves are commonly probed via macros in some downstream
+ * code. Mirror with #ifndef so any later #include of the real header
+ * (e.g. through a Motif build pulling system X11 headers) does not
+ * collide on the enum tag. */
+#ifndef IceProcessMessagesSuccess
+typedef enum {
+    IceProcessMessagesSuccess = 0,
+    IceProcessMessagesIOError = 1,
+    IceProcessMessagesConnectionClosed = 2
+} IceProcessMessagesStatus;
+#endif
+
+#endif /* _LIBX11_COMPAT_ICELIB_H_ */

include/X11/SM/SMlib.h

@@ -0,0 +1,115 @@
+/* Stub X11/SM/SMlib.h for libx11-compat's libXt build
+ *
+ * Copyright 2026 libx11-compat contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+/* libXt's generated Shell.h unconditionally includes this header even
+ * when session management is compiled out via XT_NO_SM. ShellP.h also
+ * declares a SmcConn slot in the WidgetClass record so the struct layout
+ * stays binary-compatible. libx11-compat ships no libSM and runs in a
+ * single process with no XSMP peer, so the type lives only as an opaque
+ * pointer here and the few constants that downstream code probes are
+ * synthesized as enums.
+ */
+#ifndef _LIBX11_COMPAT_SMLIB_H_
+#define _LIBX11_COMPAT_SMLIB_H_
+
+#include <X11/Xfuncproto.h>
+#include <X11/Xosdefs.h>
+
+typedef struct _SmcConn *SmcConn;
+typedef struct _SmsConn *SmsConn;
+typedef void *SmPointer;
+
+typedef struct {
+    int length;
+    SmPointer value;
+} SmPropValue;
+
+typedef struct {
+    char *name;
+    char *type;
+    int num_vals;
+    SmPropValue *vals;
+} SmProp;
+
+typedef int SmcCallbacks;
+
+/* Real libSM ships these as #define macros, so we mirror the same shape
+ * with #ifndef guards. Using `enum { SmProtoMajor = 1, ... }` here would
+ * conflict at preprocess time if any consumer also pulled in the system
+ * <X11/SM/SMlib.h>, because its `#define SmProtoMajor 1` would expand
+ * inside our enum declaration to `1 = 1`. */
+#ifndef SmProtoMajor
+#define SmProtoMajor 1
+#endif
+#ifndef SmProtoMinor
+#define SmProtoMinor 0
+#endif
+#ifndef SmDialogError
+#define SmDialogError 0
+#endif
+#ifndef SmDialogNormal
+#define SmDialogNormal 1
+#endif
+#ifndef SmInteractStyleNone
+#define SmInteractStyleNone 0
+#endif
+#ifndef SmInteractStyleErrors
+#define SmInteractStyleErrors 1
+#endif
+#ifndef SmInteractStyleAny
+#define SmInteractStyleAny 2
+#endif
+#ifndef SmSaveGlobal
+#define SmSaveGlobal 0
+#endif
+#ifndef SmSaveLocal
+#define SmSaveLocal 1
+#endif
+#ifndef SmSaveBoth
+#define SmSaveBoth 2
+#endif
+#ifndef SmRestartIfRunning
+#define SmRestartIfRunning 0
+#endif
+#ifndef SmRestartAnyway
+#define SmRestartAnyway 1
+#endif
+#ifndef SmRestartImmediately
+#define SmRestartImmediately 2
+#endif
+#ifndef SmRestartNever
+#define SmRestartNever 3
+#endif
+#ifndef SmcSaveYourselfProcMask
+#define SmcSaveYourselfProcMask 1
+#endif
+#ifndef SmcDieProcMask
+#define SmcDieProcMask 2
+#endif
+#ifndef SmcSaveCompleteProcMask
+#define SmcSaveCompleteProcMask 4
+#endif
+#ifndef SmcShutdownCancelledProcMask
+#define SmcShutdownCancelledProcMask 8
+#endif
+
+#define SmCloneCommand "CloneCommand"
+#define SmCurrentDirectory "CurrentDirectory"
+#define SmDiscardCommand "DiscardCommand"
+#define SmEnvironment "Environment"
+#define SmProcessID "ProcessID"
+#define SmProgram "Program"
+#define SmResignCommand "ResignCommand"
+#define SmRestartCommand "RestartCommand"
+#define SmRestartStyleHint "RestartStyleHint"
+#define SmShutdownCommand "ShutdownCommand"
+#define SmUserID "UserID"
+
+#define SmARRAY8 "ARRAY8"
+#define SmCARD8 "CARD8"
+#define SmLISTofARRAY8 "LISTofARRAY8"
+
+#endif /* _LIBX11_COMPAT_SMLIB_H_ */

include/X11/Xmu/Editres.h

@@ -0,0 +1,35 @@
+/* Stub Xmu/Editres.h for libx11-compat's libXt build
+ *
+ * Copyright 2026 libx11-compat contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+/* The real Xmu/Editres.h declares the editres-protocol hook that libXt's
+ * Shell.c registers so an external editres client can introspect a live
+ * widget tree. libx11-compat ships no Xmu, no editres client targets this
+ * in-process display, and Shell.c's only use is the function-pointer
+ * registration. A no-op _XEditResCheckMessages keeps Shell.c compilable
+ * and link-safe without dragging libXmu into the build.
+ */
+#ifndef _XMU_EDITRES_H_
+#define _XMU_EDITRES_H_
+
+#include <X11/Intrinsic.h>
+
+#define EDITRES_NAME "Editres"
+#define EDITRES_COMMAND_ATOM "Comm"
+#define EDITRES_PROTOCOL_ATOM "EditresProtocol"
+#define EDITRES_VERSION 5
+
+static inline void _XEditResCheckMessages(Widget widget,
+                                          XtPointer data,
+                                          XEvent *event,
+                                          Boolean *cont)
+{
+    (void) widget;
+    (void) data;
+    (void) event;
+    (void) cont;
+}
+
+#endif /* _XMU_EDITRES_H_ */

include/libxt-build/config.h

@@ -0,0 +1,55 @@
+/* Synthesized config.h for the libXt build inside libx11-compat
+ *
+ * Copyright 2026 libx11-compat contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+/* libXt expects an autoconf-generated config.h to define a handful of
+ * platform knobs. We are not running autoconf, so the knobs are pinned
+ * to values that match the modern macOS / Linux environments libx11-compat
+ * targets: poll(2) is always available, threads are enabled, and the
+ * session-management surface is disabled so libICE/libSM stay out of the
+ * dependency closure (see mk/libxt.mk).
+ *
+ * This header lives under include/libxt-build/ rather than the X11/
+ * namespace because the basename ``config.h'' is too generic to share an
+ * include path with anything else. mk/libxt.mk adds the parent directory
+ * to the include path *only* for the libXt translation units.
+ */
+
+#ifndef LIBX11_COMPAT_LIBXT_CONFIG_H
+#define LIBX11_COMPAT_LIBXT_CONFIG_H
+
+#define PACKAGE_NAME "libXt"
+#define PACKAGE_VERSION "1.3.1"
+#define PACKAGE_STRING "libXt 1.3.1"
+#define PACKAGE_BUGREPORT "https://github.com/sysprog21/libx11-compat/issues"
+#define VERSION PACKAGE_VERSION
+
+/* poll() is on every libx11-compat-supported platform. The select() fallback
+ * path in NextEvent.c is bit-set-sized and predates large fd numbers; we
+ * never want it. */
+#define USE_POLL 1
+
+/* Multi-threaded toolkit. Wires Threads.c's mutex hooks into the XtAppLock
+ * machinery so XtAppContexts can be shared across threads. */
+#define XTHREADS 1
+
+/* Disable session-management hooks in Shell.c so libICE / libSM stay out
+ * of the link line. SDL has no notion of XSMP and the in-process display
+ * has no peer to negotiate with. */
+#define XT_NO_SM 1
+
+/* HAVE_REALLOCARRAY left undefined deliberately. reallocarray() exists in
+ * Apple's libSystem and glibc >= 2.26, but the macOS SDK does not declare
+ * it in <stdlib.h> even with _DARWIN_C_SOURCE, so the implicit-declaration
+ * error kills the build before the linker would have found it. libXt's
+ * Alloc.c falls back to Xrealloc + an explicit overflow check when this
+ * macro is absent, which costs nothing in performance and works on every
+ * supported host. */
+
+/* asprintf is on every glibc and Apple libc. Initialize.c uses it for
+ * defaults-file path assembly. */
+#define HAVE_ASPRINTF 1
+
+#endif /* LIBX11_COMPAT_LIBXT_CONFIG_H */