No major new features are planned for VHDL Mode. I'm rather focussing on bug fixes and small enhancements.
Moving forward VHDL Mode is only tested on the latest GNU Emacs version (currently GNU Emacs 28/29). Therefore compatibility with older GNU Emacs versions as well as XEmacs are not guaranteed. In case of compatibility issues I recommend to stick with older versions or update Emacs.
In case of loading errors in older Emacs versions I recommend to try to remove vhdl-mode.elc and directly load vhdl-mode.el instead.
Enhancement: Add VHDL-2019 support (keywords & indentation). Customize with option `vhdl-standard'.
Enhancement: Enhance compilation error parsing to
distinguish between errors, warnings and info messages.
Enhancement: Enhance compilation error parsing for ModelSim.
Enhancement: Add compilation error parsing for Xilinx Vivado.
Bug fix: Fix indentation for C-directives.
Bug fix: Fix indentation for types in interface lists.
Bug fix: Fix indentation for with-select statement.
Bug fix: Fix indentation for conditional assignments.
Bug fix: Fix indentation for if-generate statement.
Bug fix: Fix indentation for postponed process.
3.38.4 (2022-09-08)
Enhancement: Add option `vhdl-testbench-include-libraries'
for libraries to be included in generated testbench.
Enhancement: Add option `vhdl-testbench-include-custom-library'
to include custom library clause in generated testbench.
Enhancement: Support case-generate statement in template generation and indentation.
3.38.3 (2022-02-01)
Enhancement: Support "elsif/else generate" (VHDL'08).
Bug fix: Minor indentation bug fix.
Bug fix: Indentation fixes for "package" and "protected type".
Bug fix: Fix wrapping of too long comment lines.
Enhancement:: Add option `vhdl-auto-wrap-comments' to turn
automatic comment wrapping off.
Enhancement: Add option `vhdl-optional-labels-at-end' to omit
labels at end of constructs.
3.37 (2015-02-10)
Enhancement: Add VHDL'08 support.
Note: The setting for option `comment-padding' has been
removed, so that the Emacs default value is now used. By default this
causes "-- " to be inserted when commenting a region instead of "--".
This fixes incorrect uncommenting of code regions that contain comment
lines. The old behavior can be restored by customizing option
`comment-padding' with "" (empty string).
3.36 (2014-11-27)
Enhancement: Enhance regular expressions for compilation error
parsing. Also change default value for
'vhdl-compile-use-local-error-regexp' to nil. The reason is to limit
the impact on other commands and language compilers.
Maintenance: Replace functions from deprecated assoc.el
package.
3.35 (2014-03-11)
Enhancement: Remove use of deprecated `assoc.el' package.
Enhancement: Include tabify/untabify in beautification.
Enhancement: Makefile generation: support compilers with no
unit-to-file name mapping.
Bug fix: Minor bug fixes.
3.34 (2012-11-21)
Enhancement: Support compilation error parsing for new
`compile.el' package in GNU Emacs 22/23/24.
Enhancement: Improved code beautification. Force some keywords
(like "begin") on a separate line to guarantee correct indentation.
Variable `vhdl-beautify-options' allows to control individual
beautification features when running beautification command.
Enhancement: Improved sensitivity list updating.
Enhancement: Port translation: Derive actual generic name
from formal generic name.
Bug fix: Minor bug fixes.
3.33.28 (2010-07-27)
Note: In GNU Emacs 23 the default value for custom option
'comment-style' has changed from 'plain' to 'indent'. This causes
different commenting behavior (comment/uncomment out region). To
restore the old behavior the option has to be customized back to
'plain'.
Enhancement: Add support for GHDL compiler. Make GHDL the
default compiler.
Enhancement: Add command 'vhdl-fix-clause-buffer' and menu
entry "VHDL -> Fix -> Generic/Port Clause Buffer" to fix all
clauses in buffer at once.
Enhancement: Support direct instantiation in 'imenu'.
Bug fix: Fix parsing of extended identifiers in port copying.
Bug fix: Various indentation fixes.
Bug fix: Minor bug fixes for highlighting and speedbar.
3.33.27 (2008-11-27)
Enhancement: Special syntax highlighting (option
`vhdl-highlight-special-words') now allows to highlight words inside
comments ("In comments" switch in option `vhdl-special-syntax-alist').
Bug fix: Fix comment filling in Emacs 22.
Bug fix: Minor bug fixes in sensitivity list updating.
3.33.26 (2008-08-07)
Enhancement: TAB now indents region if a region is active
(selected). Compatible with new standard behavior in Emacs 23 (not
in XEmacs).
Bug fix: Fix indentation of clock templates in testbench
insertion.
Bug fix: Improve highlighting of component instantiations.
Enhancement: Add / update support for VHDL-AMS packages.
Include templates for package use clause insertion.
Add highlighting / word expansion for standardized constant and
types.
Enhancement: Update reserved words for math packages.
Enhancement: Highlighting / case-fixing for standardized
constants.
Bug fix: Fix indentation for lines with '^L' (formfeed)
character.
Bug fix: Minor bug fixes.
3.33.24 (2008-05-08)
Enhancement: Add "authorfull" keyword to VHDL header template
(inserts author full name without login name, email address).
Enhancement: New option to also add array indices and record
fields in sensitivity list instead of just the signal names
(option `vhdl-array-index-record-field-in-sensitivity-list').
Bug fix: Use correct initialization values for "integer" and
"real" types in pasting ports as testbench.
Bug fix: Fix handling of "terminal" type (VHDL-AMS) in
pasting ports.
Bug fix: Minor bug fixes.
3.33.23 (2008-04-01)
Compatibility: Change some key bindings for Emacs
compatibility (i.e. not use `C-c [a-zA-Z]' bindings in a major
mode, reserved as user bindings). Most importantly the key
binding for `vhdl-comment-uncomment-region' changed from `C-c c'
to `C-c C-c'. Other changed bindings are listed in the integrated
release notes (Menu "VHDL" -> "Documentation" -> "Release Notes").
3.33.22 (2007-12-21)
Bug fix: Fix sensitivity list updating for record fields.
Bug fix: Fix template for "variable" keyword inside labeled
process.
3.33.20 (2007-07-27)
Bug fix: Small bug fixes in code alignment and case fixing.
Distribution: Removed out-of-date patches of speedbar and
hideshow packages.
3.33.19 (2007-06-22)
Bug fix: Also consider "==" VHDL-AMS assignment operator in
indentation.
Bug fix: Correctly adjust case of keywords after "end".
3.33.18 (2007-05-15)
Bug fix: Minor bug fixes, enhancements.
3.33.17 (2006-12-12)
Bug fix: Handle extended identifiers in code beautification.
3.33.16 (2006-09-19)
Bug fix: Fix indentation of comments at beginning of line.
Bug fix: Not align keywords inside comments.
3.33.15 (2006-09-15)
Enhancement: Indent comment lines like following (instead of
preceding) code line. Gives nicer indentation when comments
belong to the code that follows. Old behavior can be restored
using option `vhdl-indent-comment-like-next-code-line'.
3.33.14 (2006-08-21)
Bug fix: Fix error message regexp for Modelsim.
3.33.13 (2006-08-16)
Enhancement: Customize Makefile default targets (new option
`vhdl-makefile-default-targets').
Enhancement: Add support for "ADVance MS" compiler.
Bug fix: Minor bug fixes.
3.33.12 (2006-05-23)
Bug fix: Fix indentation bug for simultaneous
if/case-statements.
Enhancement: Enhance code alignment.
3.33.11 (2006-05-15)
Bug fix: Fix indentation bug for argument lists.
Bug fix: Fix code alignment/beautifying bugs.
3.33.10 (2006-05-11)
Enhancement: Use relative instead of absolute path for files
when compiling (`vhdl-compile').
Bug fix: Fix indentation bug.
3.33.9 (2006-04-12)
Enhancement: Add support for "Aldec" simulator.
Enhancement: Update to VHDL'02 standard (add 'protected'
keyword, but indentation not supported yet).
Bug fix: Minor bug fixes.
3.33.8 (2005-12-20)
Bug fix: Undo comment filling fix for XEmacs (broke
beautification).
3.33.7 (2005-12-09)
Enhancement: Better support for extended identifiers.
Enhancement: Add compilation support for Xilinx compiler.
Bug fix: Comment filling in XEmacs.
Bug fix: Fix VHDL-AMS "case...use" and "if...use" constructs.
Bug fix: Minor bug fixes.
3.33.5 (2005-06-22)
Bug fix: Incompatibility issue with XEmacs, minor fixes.
3.33.4 (2005-05-17)
Bug fix: Identify signals read as index in multi-dimensional
arrays in sensitivity list updating.
3.33.3 (2005-02-25)
Enhancement: Set default project (at startup) within "Project"
menu.
Enhancement: Handle extended identifiers for generics in
port copying.
Enhancement: Query for target in "Make" command, use last
target as default.
New release: Configuration declaration generation.
3.32.21 (2004-09-23)
Bug fix: Fix infinite loop bug in code beautification.
Bug fix: Correctly identify signals used as array index as
read signals in sensitivity list updating.
3.32.20 (2004-02-16)
Enhancement: Separate customization of entity and architecture
file names for testbenches (new options 'vhdl-testbench-entity-file-name' and
'vhdl-testbench-architecture-file-name').
Documentation: Add note that package and testbench files can
be placed in separate directories (see options
'vhdl-package-file-name', 'vhdl-testbench-entity-file-name' and
'vhdl-testbench-architecture-file-name').
Bug fix: Improve indentation of "record" type declaration.
Bug fix: Whitespace fixing in comments (beautification).
3.32.19 (2003-12-18)
Bug fix: Beautify inserts too many spaces after comma/string.
3.32.18 (2003-11-17)
Bug fix: Define alias for missing 'member-ignore-case'
function in XEmacs.
3.32.17 (2003-09-17)
Enhancement: Add Makefile generation information for Cadence NC.
Bug fix: Ignore different case of signals read in a process
for sensitivity list updating.
3.32.16 (2003-09-08)
Bug fix: Case change on identifiers in port translation.
3.32.15 (2003-08-04)
Bug fix: Some signals were not correctly detected as being
read.
3.32.14 (2003-04-21)
Bug fix: Include aliases, not include formal parameters in
sensitivity lists.
3.32.13 (2003-03-12)
Bug fix: Beautification of character literals (e.g. ':').
3.32.12 (2003-02-28)
Bug fix: Indentation of comment line with string inside.
3.32.11 (2002-11-12)
Enhancement: Allow changing case when deriving file names from
VHDL unit names (option `vhdl-file-name-case').
3.32.10 (2002-10-27)
Bug fix: Indentation after comment lines in XEmacs 21.4+
(works around buggy `forward-comment' built-in function in XEmacs 21.4).
Minor enhancements.
3.32.9 beta (2002-07-01)
New feature: Subprogram translation.
New feature: Code filling.
New feature: Code statistics.
Enhancement: Hierarchy scanning finds component instantiations
with no generic/port maps (VHDL'93 syntax only using keywords
"component", "entity" or "configuration").