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Fix clippy explicit_write lint for new writeln implementation

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This commit is contained in:
David Tolnay 2022-05-22 17:39:44 -07:00
parent e885157f03
commit 8ec9e5e161
1 changed files with 34 additions and 2 deletions
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36
clippy_lints/src/explicit_write.rs
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@ -4,7 +4,8 @@ use clippy_utils::source::snippet_with_applicability;
use clippy_utils::{is_expn_of, match_function_call, paths};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_hir::def::Res;
use rustc_hir::{BindingAnnotation, Block, BlockCheckMode, Expr, ExprKind, Node, PatKind, QPath, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
@ -39,7 +40,7 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
if let ExprKind::MethodCall(unwrap_fun, [write_call], _) = expr.kind;
if unwrap_fun.ident.name == sym::unwrap;
// match call to write_fmt
if let ExprKind::MethodCall(write_fun, [write_recv, write_arg], _) = write_call.kind;
if let ExprKind::MethodCall(write_fun, [write_recv, write_arg], _) = look_in_block(cx, &write_call.kind);
if write_fun.ident.name == sym!(write_fmt);
// match calls to std::io::stdout() / std::io::stderr ()
if let Some(dest_name) = if match_function_call(cx, write_recv, &paths::STDOUT).is_some() {
@ -100,3 +101,34 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
}
}
}
/// If `kind` is a block that looks like `{ let result = $expr; result }` then
/// returns $expr. Otherwise returns `kind`.
fn look_in_block<'tcx, 'hir>(cx: &LateContext<'tcx>, kind: &'tcx ExprKind<'hir>) -> &'tcx ExprKind<'hir> {
if_chain! {
if let ExprKind::Block(block, _label @ None) = kind;
if let Block {
stmts: [Stmt { kind: StmtKind::Local(local), .. }],
expr: Some(expr_end_of_block),
rules: BlockCheckMode::DefaultBlock,
..
} = block;
// Find id of the local that expr_end_of_block resolves to
if let ExprKind::Path(QPath::Resolved(None, expr_path)) = expr_end_of_block.kind;
if let Res::Local(expr_res) = expr_path.res;
if let Some(Node::Binding(res_pat)) = cx.tcx.hir().find(expr_res);
// Find id of the local we found in the block
if let PatKind::Binding(BindingAnnotation::Unannotated, local_hir_id, _ident, None) = local.pat.kind;
// If those two are the same hir id
if res_pat.hir_id == local_hir_id;
if let Some(init) = local.init;
then {
return &init.kind;
}
}
kind
}