Index: generic/tkFont.c
==================================================================
--- generic/tkFont.c
+++ generic/tkFont.c
@@ -94,11 +94,11 @@
     const char *string;		/* The string that was layed out. */
     int width;			/* The maximum width of all lines in the text
 				 * layout. */
     int numChunks;		/* Number of chunks actually used in following
 				 * array. */
-    LayoutChunk chunks[1];	/* Array of chunks. The actual size will be
+    LayoutChunk chunks[TKFLEXARRAY];/* Array of chunks. The actual size will be
 				 * maxChunks. THIS FIELD MUST BE THE LAST IN
 				 * THE STRUCTURE. */
 } TextLayout;
 
 /*

Index: generic/tkInt.h
==================================================================
--- generic/tkInt.h
+++ generic/tkInt.h
@@ -78,10 +78,16 @@
 #	define TkSizeT size_t
 #   else
 #	define TkSizeT int
 #   endif
 #endif
+
+#if defined(__GNUC__) && (__GNUC__ > 2)
+#   define TKFLEXARRAY 0
+#else
+#   define TKFLEXARRAY 1
+#endif
 
 #if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 7)
 # define Tcl_WCharToUtfDString ((char * (*)(const WCHAR *, int len, Tcl_DString *))Tcl_UniCharToUtfDString)
 # define Tcl_UtfToWCharDString ((WCHAR * (*)(const char *, int len, Tcl_DString *))Tcl_UtfToUniCharDString)
 # define Tcl_Char16ToUtfDString Tcl_UniCharToUtfDString

Index: generic/tkSelect.c
==================================================================
--- generic/tkSelect.c
+++ generic/tkSelect.c
@@ -26,11 +26,11 @@
     int charOffset;		/* The offset of the next char to retrieve. */
     int byteOffset;		/* The expected byte offset of the next
 				 * chunk. */
     char buffer[4];		/* A buffer to hold part of a UTF character
 				 * that is split across chunks. */
-    char command[1];		/* Command to invoke. Actual space is
+    char command[TKFLEXARRAY];		/* Command to invoke. Actual space is
 				 * allocated as large as necessary. This must
 				 * be the last entry in the structure. */
 } CommandInfo;
 
 /*

Index: generic/tkText.h
==================================================================
--- generic/tkText.h
+++ generic/tkText.h
@@ -166,11 +166,11 @@
 				/* Next in list of segments for this line, or
 				 * NULL for end of list. */
     TkSizeT size;			/* Size of this segment (# of bytes of index
 				 * space it occupies). */
     union {
-	char chars[2];		/* Characters that make up character info.
+	char chars[TKFLEXARRAY];		/* Characters that make up character info.
 				 * Actual length varies to hold as many
 				 * characters as needed.*/
 	TkTextToggle toggle;	/* Information about tag toggle. */
 	TkTextMark mark;	/* Information about mark. */
 	TkTextEmbWindow ew;	/* Information about embedded window. */
@@ -487,11 +487,11 @@
     double lastTab;		/* The accurate fractional pixel position of
 				 * the last tab. */
     double tabIncrement;	/* The accurate fractional pixel increment
 				 * between interpolated tabs we have to create
 				 * when we exceed numTabs. */
-    TkTextTab tabs[1];		/* Array of tabs. The actual size will be
+    TkTextTab tabs[TKFLEXARRAY];/* Array of tabs. The actual size will be
 				 * numTabs. THIS FIELD MUST BE THE LAST IN THE
 				 * STRUCTURE. */
 } TkTextTabArray;
 
 /*

Index: generic/tkTextDisp.c
==================================================================
--- generic/tkTextDisp.c
+++ generic/tkTextDisp.c
@@ -442,11 +442,11 @@
 
 #if !TK_LAYOUT_WITH_BASE_CHUNKS
 
 typedef struct CharInfo {
     int numBytes;		/* Number of bytes to display. */
-    char chars[1];		/* UTF characters to display.
+    char chars[TKFLEXARRAY];		/* UTF characters to display.
 				 * Allocated as large as necessary. THIS MUST BE THE LAST
 				 * FIELD IN THE STRUCTURE. */
 } CharInfo;
 
 #else /* TK_LAYOUT_WITH_BASE_CHUNKS */

Index: unix/tkUnixWm.c
==================================================================
--- unix/tkUnixWm.c
+++ unix/tkUnixWm.c
@@ -26,11 +26,11 @@
     struct ProtocolHandler *nextPtr;
 				/* Next in list of protocol handlers for the
 				 * same top-level window, or NULL for end of
 				 * list. */
     Tcl_Interp *interp;	/* Interpreter in which to invoke command. */
-    char command[1];		/* Tcl command to invoke when a client message
+    char command[TKFLEXARRAY];	/* Tcl command to invoke when a client message
 				 * for this protocol arrives. The actual size
 				 * of the structure varies to accommodate the
 				 * needs of the actual command. THIS MUST BE
 				 * THE LAST FIELD OF THE STRUCTURE. */
 } ProtocolHandler;

Index: win/tkWinWm.c
==================================================================
--- win/tkWinWm.c
+++ win/tkWinWm.c
@@ -56,11 +56,11 @@
     struct ProtocolHandler *nextPtr;
 				/* Next in list of protocol handlers for the
 				 * same top-level window, or NULL for end of
 				 * list. */
     Tcl_Interp *interp;	/* Interpreter in which to invoke command. */
-    char command[1];		/* Tcl command to invoke when a client message
+    char command[TKFLEXARRAY];	/* Tcl command to invoke when a client message
 				 * for this protocol arrives. The actual size
 				 * of the structure varies to accommodate the
 				 * needs of the actual command. THIS MUST BE
 				 * THE LAST FIELD OF THE STRUCTURE. */
 } ProtocolHandler;