56 lines
1.8 KiB
Rust
56 lines
1.8 KiB
Rust
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use crate::utils::{is_direct_expn_of, span_lint_and_help};
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use if_chain::if_chain;
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use rustc::lint::in_external_macro;
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use rustc_lint::{EarlyContext, EarlyLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use syntax::ast::*;
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `option_env!(...).unwrap()` and
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/// suggests usage of the `env!` macro.
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///
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/// **Why is this bad?** Unwrapping the result of `option_env!` will panic
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/// at run-time if the environment variable doesn't exist, whereas `env!`
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/// catches it at compile-time.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust,no_run
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/// let _ = option_env!("HOME").unwrap();
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/// ```
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///
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/// Is better expressed as:
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///
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/// ```rust,no_run
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/// let _ = env!("HOME");
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/// ```
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pub OPTION_ENV_UNWRAP,
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correctness,
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"using `option_env!(...).unwrap()` to get environment variable"
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}
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declare_lint_pass!(OptionEnvUnwrap => [OPTION_ENV_UNWRAP]);
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impl EarlyLintPass for OptionEnvUnwrap {
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
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if_chain! {
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if !in_external_macro(cx.sess, expr.span);
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if let ExprKind::MethodCall(path_segment, args) = &expr.kind;
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if path_segment.ident.as_str() == "unwrap";
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if let ExprKind::Call(caller, _) = &args[0].kind;
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if is_direct_expn_of(caller.span, "option_env").is_some();
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then {
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span_lint_and_help(
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cx,
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OPTION_ENV_UNWRAP,
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expr.span,
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"this will panic at run-time if the environment variable doesn't exist",
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"consider using the `env!` macro instead"
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);
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}
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}
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}
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}
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