Improve linter analyzer ergonomics: ctxbackground autofix, test-file parity, and range diagnostics

[Copilot]

This update addresses drift in our golang.org/x/tools/go/analysis usage by tightening analyzer behavior and editor UX in pkg/linters. It focuses on the highest-leverage items from the module review: ctxbackground traversal/fixability, consistent test-file handling, and range-based diagnostics.

• ctxbackground: single-pass traversal + autofix

  • Replaced function-body ast.Inspect walk with inspector.WithStack call-level traversal to use the shared inspector pipeline end-to-end.
  • Added _test.go skip behavior to match analyzer suite conventions.
  • Added SuggestedFix for mechanical replacement of context.Background() with the in-scope context.Context parameter.

• Shared _test.go filtering helper

  • Added pkg/linters/internal/filecheck.IsTestFile(...).
  • Switched duplicate filename suffix checks in ctxbackground, errormessage, errstringmatch, osexitinlibrary, and rawloginlib to the shared helper.

• Range-based diagnostics (ReportRangef)

  • Migrated position-only reports to range-based reporting in:
    • largefunc
    • excessivefuncparams
    • errormessage
    • errstringmatch
    • osexitinlibrary
    • rawloginlib
  • In largefunc, range reporting highlights function declarations more precisely for named functions.

• Targeted analyzer testdata

  • Added ctxbackground _test.go fixture to assert test-file calls are ignored.

pass.Report(analysis.Diagnostic{
    Pos:     call.Pos(),
    End:     call.End(),
    Message: "use the context.Context parameter instead of context.Background()",
    SuggestedFixes: []analysis.SuggestedFix{
        {
            Message: "Replace context.Background() with context parameter",
            TextEdits: []analysis.TextEdit{{
                Pos: call.Pos(), End: call.End(), NewText: []byte(ctxParamName),
            }},
        },
    },
})

[Copilot]

Pull request overview

This PR improves ergonomics and consistency across several go/analysis-based linters by standardizing _test.go handling, upgrading diagnostics to report source ranges (better editor highlighting), and enhancing ctxbackground with a targeted autofix.

Changes:

• Added a shared filecheck.IsTestFile(...) helper and applied it across multiple analyzers to consistently skip _test.go files.
• Migrated several analyzers from position-only diagnostics to range-based diagnostics via pass.ReportRangef(...).
• Reworked ctxbackground to use inspector.WithStack for traversal and added a SuggestedFix that replaces context.Background() with the in-scope context.Context parameter; added testdata asserting _test.go is ignored.

Show a summary per file

File	Description
pkg/linters/rawloginlib/rawloginlib.go	Uses shared _test.go detection and reports diagnostics over call expression ranges.
pkg/linters/osexitinlibrary/osexitinlibrary.go	Uses shared _test.go detection and reports diagnostics over call expression ranges.
pkg/linters/largefunc/largefunc.go	Switches large-function diagnostics to range-based reporting with refined highlight targets.
pkg/linters/internal/filecheck/filecheck.go	Introduces shared helper for identifying Go test files by filename.
pkg/linters/excessivefuncparams/excessivefuncparams.go	Updates diagnostics to use range-based reporting on the function name identifier.
pkg/linters/errstringmatch/errstringmatch.go	Uses shared _test.go detection and reports diagnostics over the matched call range.
pkg/linters/errormessage/errormessage.go	Uses shared _test.go detection and converts multiple reports to range-based diagnostics.
pkg/linters/ctxbackground/testdata/src/ctxbackground/ctxbackground_test.go	Adds fixture ensuring _test.go code is ignored by the analyzer.
pkg/linters/ctxbackground/ctxbackground.go	Refactors traversal to WithStack, skips _test.go, and adds a SuggestedFix to replace context.Background() with a context parameter.

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• Files reviewed: 9/9 changed files
• Comments generated: 0