Disabling formatting

Skip one declaration, statement, or group

Place the marker in a comment immediately before the construct or group to preserve:

module example;
    // slang-format: skip
    localparam int MASK = (1<<4) | (1<<1);

    localparam int other=2;
endmodule

The MASK declaration keeps its existing spacing. The other declaration is formatted normally. A skipped declaration also separates the alignment groups on either side of it.

The marker applies to a complete declaration or statement, including its nested contents. For example, place it before an always block to preserve that whole block. It is not a general way to skip an arbitrary expression or port-list entry. Use the exact, case-sensitive spelling slang-format: skip; a block comment containing the same marker is also accepted.

Prefer skip to off/on directives, since an unmatched off can disable formatting for the rest of its list.

Disable a region

Put the markers on their own comment lines, between items in the same list:

module example;
    // slang-format: off
    localparam int LEFT=1;localparam int RIGHT= 2;
    // slang-format: on
    localparam int normal=3;
endmodule

The two declarations in the disabled region retain their internal spacing, including the space between them. Formatting resumes at normal. The formatter can adjust the indentation at the region boundary and format the marker comments.

Each list has its own off/on state: the file's declarations, module or class members, a block's statements, or a port or argument list. Markers must sit between complete items in that list, not inside an expression. Inline lists such as the names within one variable declaration do not support region markers.

An on inside a nested scope cannot close an outer off, and an on after the scope ends cannot close an off inside it:

module example;
    initial begin
        // slang-format: off
        a=1;b=2;
    end
    // slang-format: on
    logic c;
endmodule

Here the assignments are preserved, but the on is in the module's member list, not the block's statement list. Formatting resumes when the block ends, and the formatter warns:

slang-format: on has no preceding off in the same list scope. Did you put the off directive in the wrong scope?

An unmatched off silently preserves the rest of its list. An unmatched on produces the warning above, and formatting continues; the warning does not reject the file or change the exit status. Repeated off markers in the same list do not nest: the next on resumes formatting. Both markers also work in standalone block comments.

Disable a whole file

Put off before the first declaration to preserve every declaration in the file:

// slang-format: off
module first;logic a;endmodule
module second;logic b;endmodule

No final on is needed, and this produces no warning. To resume formatting later in the file, put on between top-level declarations; placing it inside a module would put it in a different list scope.

Generated files

For generated source, put @generated in a leading comment:

// @generated
module first;logic a;endmodule
module second;logic b;endmodule

The formatter returns the whole file unchanged. A leading block comment works too. The marker must be in the comments before the first source token; @generated in a later comment or a string is not a file exclusion.

Interaction with validation and force

skip and off/on regions preserve formatting; the source is still parsed and validated. They do not hide syntax errors or merge conflict markers. See validation for how those diagnostics affect output.

--force overrides validation failures and still respects skip, off/on regions, and generated file exclusions. An unmatched-on warning does not require force.