Language Support
- Implemented all of the rules related to assertion local variable definite assignment flow. slang will now diagnose use of assertion locals before they have been assigned, according to the rules in the LRM.
- Explicit package export directives now correctly require a corresponding import (wildcard or explicit)
- Non-variable and non-output ANSI port declarations are now correctly prevented from specifying an initializer expression
- Parameter port declarations now correctly require an explicit keyword when an implicit type syntax with dimensions or signing keyword is used
- Covergroup formal arguments are now correctly always considered
const - Checker arguments that reference automatic variables or have const casts are now correctly disallowed from being used in procedural code
- Checker procedures are now correctly disallowed from referencing covergroup types
- Removed the restriction that covergroup expressions must be constant expressions -- the implementation was buggy, other tools don't implement it, and the details in the LRM are not well defined
- Modport ports now correctly require that their target references are members of their parent interface
- Explicit port expressions now correctly require that their target references are members of their parent module
- Tasks that contain blocking timing controls are now correctly disallowed from being called from always_comb/latch/ff blocks
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 beforeconstraints, for compatibility with other tools (on by default for 'vcs' compat mode) - Added a
--cst-jsonoption to serialize the concrete syntax tree to JSON (thanks to @AndrewNolte) - Added
--allow-genblk-referenceas a compatibility option to allow referencing unnamed generate blocks via their external names (thanks to @toddstrader) - Added a
--diag-column-unitoption 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-sortoption to sort dependencies written to depfiles in topological order according to their use in the design (thanks to @AndrewNolte) - Added a
--depfile-trimoption to remove dependencies from the written depfile that aren't actually used in the design (thanks to @AndrewNolte) - The
--compatflag now acceptsallto 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-includesflag to mimic the behavior of VCS where`includedirectives don't search relative to the including file - The
--stdargument now accepts1364-2005as a value, which disables all SystemVerilog keywords during parsing for Verilog compatibility (thanks to @povik) - Added a
--map-keyword-versionoption 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
`includedirectives 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-instancesis 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
Lexerclass is now exposed to the Python bindings (thanks to @paulgrahek) - Fixed binding of Diagnostic arguments, exposed DiagnosticEngine::formatArg
slang-tidy
- The
--skip-fileand--skip-pathslang-tidy options now also imply--suppress-warningsfor 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-blanklinesoption to remove extra blank lines in the rewritten output (thanks to @AndrewNolte)