fprintferrorunchecked (76th linter): AssignStmt-only filter misses 938 bare ExprStmt call sites #65225

Linter: fprintferrorunchecked (76th registered analyzer, PR #65073, added 2026-10-02, first-ever audit)

Problem

The entire analysis is gated by a single nodeFilter entry:

nodeFilter := []ast.Node{(*ast.AssignStmt)(nil)}

(fprintferrorunchecked.go:40). checkUncheckedFprintAssign only recognizes the explicit-blank-assignment shapes _ = fmt.Fprintf(...) and _, _ = fmt.Fprintf(...). A bare statement call with no assignment at all, e.g. fmt.Fprintf(w, "text"), is legal Go that silently discards both return values -- exactly the write-failure-ignored case this linter exists to catch -- yet it never reaches checkUncheckedFprintAssign because there is no AssignStmt node for it.

Evidence

Grep across pkg/ (excluding _test.go) for the bare-statement shape ^\tfmt\.(Fprintf|Fprintln|Fprint)\( returned 938 matches across 193 files -- vastly more common than the explicit _, _ = form this linter actually detects. Two concrete production sites:

• pkg/console/confirm.go:53-56 -- fmt.Fprintf(out, ...) writing to an io.Writer parameter (e.g. os.Stdout in real callers), with zero error handling. This is precisely the silently-ignored-write-failure scenario described in the linters own diagnostic message.
• pkg/workflow/workflow_errors.go:99 -- fmt.Fprintf(&b, ...) building an error string via bytes.Buffer.

CI enforcement

.github/workflows/cgo.yml LINTER_FLAGS already include -fprintferrorunchecked on both the native (line 1487) and wasm (line 1490) custom-linter steps with -test=false, so this gate is active in CI today while being structurally blind to the overwhelming majority of real Fprint* call sites in the codebase.

Pattern class: node_filter_too_narrow (same class previously found in globwalkignorederror/strconvparseignorederror, issues #61265/#63094), but at far larger scale here -- 938 live occurrences versus a handful in prior instances of this class.

Recommendation

Add an *ast.ExprStmt case alongside the existing *ast.AssignStmt case in run() (fprintferrorunchecked.go:40-50): unwrap the ExprStmt to its *ast.CallExpr, then reuse the existing extractFunctionName / isFprintFunction / isFprintCallReturningError / reportUncheckedFprint helpers unchanged.

Validation checklist

• Add a testdata case for the bare-statement form, e.g. fmt.Fprintf(w, "text") as a standalone ExprStmt, expecting a diagnostic
• Confirm existing AssignStmt-based good/bad cases still pass unchanged
• Run make golint-custom LINTER_FLAGS="-fprintferrorunchecked -test=false" against pkg/console and pkg/workflow to confirm the fix surfaces new findings without introducing false positives on checked calls

Effort: small -- one new ExprStmt branch reusing all existing helper functions.

Generated by 🤖 Sergo - Serena Go Expert · claude · agent · 317.8 AIC · ⌖ 7.26 AIC · ⊞ 5.3K · ◷

• expires on Oct 9, 2026, 8:11 PM UTC-08:00