Notable Breaking Changes

• AST serialization: typedefs and enum type references are now printed as links to the original definition instead of repeating the type for each usage

New Features

• Added -Wcase-none which warns about constant case statements that don't match on any items
• Added -Wunnamed-generate which warns for generate blocks that don't have a user-provided name
• Added -Wvacuous-cover which warns about cover statements for properties that allow vacuous success (which can result in misleading cover results)
• Added -Wnested-solve-before which allows downgrading the error issued for nested solve before constraints, for compatibility with other tools (on by default for 'vcs' compat mode)
• Added a --cst-json option to serialize the concrete syntax tree to JSON (thanks to @AndrewNolte)
• Added --allow-genblk-reference as a compatibility option to allow referencing unnamed generate blocks via their external names (thanks to @toddstrader)
• Added a --diag-column-unit option to control whether column numbers in diagnostics respect UTF-8 encoding and tab stop widths, which is now the new default. The old behavior can be selected with --diag-column-unit=byte.
• Added a --depfile-sort option to sort dependencies written to depfiles in topological order according to their use in the design (thanks to @AndrewNolte)
• Added a --depfile-trim option to remove dependencies from the written depfile that aren't actually used in the design (thanks to @AndrewNolte)
• The --compat flag now accepts all to enable all compatibility flags at once, to maximize the chances that slang will accept your code that works with other tools but may not comply with the LRM
• Added a --disable-local-includes flag to mimic the behavior of VCS where `include directives don't search relative to the including file
• The --std argument now accepts 1364-2005 as a value, which disables all SystemVerilog keywords during parsing for Verilog compatibility (thanks to @povik)
• Added a --map-keyword-version option to allow overriding language keyword versions for specified groups of files (thanks to @likeamahoney)

Improvements

• -Wcase-dup no longer warns if the duplicate items are all constant case items that don't match a known constant case expression
• Performing concatenation of two slashes in a macro expansion now expands to a line comment, matching the behavior of other tools
• The preprocessor will now implicitly concatenate tokens that result from back-to-back macro expansions even if there is no explicit macro concatenation operator used, to increase compatibility with other tools
• Instances that have type parameters set to identical but not technically "matching" struct types are now eligible for instance caching, which can speed up elaboration of certain designs
• -Wpacked-array-conv now also applies to cases where one side of the assignment has a multi-dimensional array type and the other does not (previously both sides had to be multi-dimensional arrays)
• The AnalysisManager API has been reworked to allow providing listener callbacks for various analysis events, to retrieve the results of assertion analysis, and to allow substituting custom data flow analysis passes in place of the default
• Duplicate packages are now diagnosed with -Wduplicate-definition, allowing them to be downgraded to a warning just like duplicate modules (thanks to @sjalloq)
• Improved the diagnostic message and source ranges reported for duplicate drivers involving modport ports to be more clear about where the connections are going
• The preprocessor now supports processing `include directives inside of macro expansions
• Drivers through ref ports are now correctly applied to their connections hierarchically
• Warnings related to wildcard port connections now contain additional context showing which port triggered the warning
• Made several tweaks to slightly improve defparam and bind evaluation performance
• The AST for multi-ports has been reworked to represent each sub port connection expression separately
• Selection of elements of dynamic types is now a downgradeable warning (-Wdynamic-non-procedural) for compatibility with other tools
• AST JSON serialization for scalar types now contains an isSigned field (thanks to @dinoruic)

Fixes

• Unnamed covergroup types now print with a placeholder name in diagnostics and AST dumping instead of just an empty string
• Fixed a bug where sequences and properties with local variable formal arguments would rewrite their formal args when expanding, potentially resulting in spurious errors
• Fixed source ranges written by AST serialization for AST nodes that don't have syntax pointers
• Fixed lint-only mode to not run the analysis pass
• Fixed a crash in analysis that could occur after exiting elaboration early due to hitting the configured error limit
• Fixed the source ranges of chained select expression AST nodes
• Fixed a preprocessor crash when encountering certain specially crafted malformed pragma directives
• Fixed expansion of __FILE__ and __LINE__ macros to use proper source locations (thanks to @g4rry1)
• Fixed a spurious error when referring to a generic class declared within a package using an explicit package scope qualifier
• Fixed a spurious error when an uninstantiated module's parameter values are set using an assignment pattern expression
• Fixed a spurious error when an uninstantiated module references an unknown instance hierarchically and --disallow-refs-to-unknown-instances is in use
• Fixed several issues where driver analysis did not correctly apply through non-trivial modport port expressions
• Fixed a parser bug that misparsed delay controls followed by an assignment pattern expression (thanks to @sjalloq)
• Fixed the AST representation of implicit named port connections for output (and inout) ports to always use an AssignmentExpression
• Fixed several bugs with direction checking of explicit ANSI port connections
• Fixed a bug where multi-driven diagnostics could print an expression path with "" as index values instead of the correct constant value
• Fixed ICE when sequence and property arguments refer to themselves in their default expressions
• Fixed ICE when pattern case items have a statement label
• Fixed ICE when recursive module instances contain certain kinds of variable name conflicts
• Fixed ICE involving unnamed recursive module instances
• Fixed a case where the max instance hierarchy depth wasn't being enforced, leading to infinite recursion
• Fixed ICE when a modport export's method name is empty
• Fixed ICE involving virtual interface types where the interface instance contains a self-referential virtual interface member
• Fixed ICE involving analysis of hierarchical calls to subroutines inside cached instance symbols
• Fixed handling of file patterns starting with recursive wildcards -- they were canonicalized incorrectly on some platforms
• Fixed infinite loop caused by recursive typedef references across packages
• Fixed --allow-use-before-declare to also apply for references to parameters
• Fixed a crash when querying bitstream width of classes containing properties with unpacked arrays of their containing class type

Tools & Bindings

pyslang

• Upgraded to pybind11 3.0, which brings improved performance, smart_holder and native_enum features
• The Lexer class is now exposed to the Python bindings (thanks to @paulgrahek)
• Fixed binding of Diagnostic arguments, exposed DiagnosticEngine::formatArg

slang-tidy

• The --skip-file and --skip-path slang-tidy options now also imply --suppress-warnings for those same paths
• Fixed the undriven range checker to handle variables with non-zero lower bounds in their range (thanks to @jameshanlon)

rewriter

• Added a --squash-blanklines option to remove extra blank lines in the rewritten output (thanks to @AndrewNolte)