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Fix expect_fun_call lint suggestions

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This commit corrects some bad suggestions produced by the
`expect_fun_call` lint and enables `rust-fix` checking on the tests.

Addresses #3630
This commit is contained in:
Michael Wright 2019-01-24 06:58:53 +02:00
parent 99c5388ce6
commit 5284b95a06
4 changed files with 254 additions and 132 deletions
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206
clippy_lints/src/methods/mod.rs
View file

@ -1148,28 +1148,6 @@ fn lint_or_fun_call(cx: &LateContext<'_, '_>, expr: &hir::Expr, method_span: Spa
/// Checks for the `EXPECT_FUN_CALL` lint.
fn lint_expect_fun_call(cx: &LateContext<'_, '_>, expr: &hir::Expr, method_span: Span, name: &str, args: &[hir::Expr]) {
fn extract_format_args(arg: &hir::Expr) -> Option<(&hir::Expr, &hir::Expr)> {
let arg = match &arg.node {
hir::ExprKind::AddrOf(_, expr) => expr,
hir::ExprKind::MethodCall(method_name, _, args)
if method_name.ident.name == "as_str" || method_name.ident.name == "as_ref" =>
{
&args[0]
},
_ => arg,
};
if let hir::ExprKind::Call(ref inner_fun, ref inner_args) = arg.node {
if is_expn_of(inner_fun.span, "format").is_some() && inner_args.len() == 1 {
if let hir::ExprKind::Call(_, format_args) = &inner_args[0].node {
return Some((&format_args[0], &format_args[1]));
}
}
}
None
}
fn generate_format_arg_snippet(
cx: &LateContext<'_, '_>,
a: &hir::Expr,
@ -1189,93 +1167,115 @@ fn lint_expect_fun_call(cx: &LateContext<'_, '_>, expr: &hir::Expr, method_span:
unreachable!()
}
fn check_general_case(
cx: &LateContext<'_, '_>,
name: &str,
method_span: Span,
self_expr: &hir::Expr,
arg: &hir::Expr,
span: Span,
) {
fn is_call(node: &hir::ExprKind) -> bool {
match node {
hir::ExprKind::AddrOf(_, expr) => {
is_call(&expr.node)
},
hir::ExprKind::Call(..)
| hir::ExprKind::MethodCall(..)
// These variants are debatable or require further examination
| hir::ExprKind::If(..)
| hir::ExprKind::Match(..)
| hir::ExprKind::Block{ .. } => true,
_ => false,
fn is_call(node: &hir::ExprKind) -> bool {
match node {
hir::ExprKind::AddrOf(_, expr) => {
is_call(&expr.node)
},
hir::ExprKind::Call(..)
| hir::ExprKind::MethodCall(..)
// These variants are debatable or require further examination
| hir::ExprKind::If(..)
| hir::ExprKind::Match(..)
| hir::ExprKind::Block{ .. } => true,
_ => false,
}
}
if args.len() != 2 || name != "expect" || !is_call(&args[1].node) {
return;
}
let receiver_type = cx.tables.expr_ty(&args[0]);
let closure_args = if match_type(cx, receiver_type, &paths::OPTION) {
"||"
} else if match_type(cx, receiver_type, &paths::RESULT) {
"|_|"
} else {
return;
};
// Strip off `&`, `as_ref()` and `as_str()` until we're left with either a `String` or `&str`
// which we call `arg_root`.
let mut arg_root = &args[1];
loop {
arg_root = match &arg_root.node {
hir::ExprKind::AddrOf(_, expr) => expr,
hir::ExprKind::MethodCall(method_name, _, call_args) => {
if call_args.len() == 1
&& (method_name.ident.name == "as_str" || method_name.ident.name == "as_ref")
&& {
let arg_type = cx.tables.expr_ty(&call_args[0]);
let base_type = walk_ptrs_ty(arg_type);
base_type.sty == ty::Str || match_type(cx, base_type, &paths::STRING)
}
{
&call_args[0]
} else {
break;
}
},
_ => break,
};
}
let span_replace_word = method_span.with_hi(expr.span.hi());
let mut applicability = Applicability::MachineApplicable;
//Special handling for `format!` as arg_root
if let hir::ExprKind::Call(ref inner_fun, ref inner_args) = arg_root.node {
if is_expn_of(inner_fun.span, "format").is_some() && inner_args.len() == 1 {
if let hir::ExprKind::Call(_, format_args) = &inner_args[0].node {
let fmt_spec = &format_args[0];
let fmt_args = &format_args[1];
let mut applicability = Applicability::MachineApplicable;
let mut args = vec![snippet(cx, fmt_spec.span, "..").into_owned()];
args.extend(generate_format_arg_snippet(cx, fmt_args, &mut applicability));
let sugg = args.join(", ");
span_lint_and_sugg(
cx,
EXPECT_FUN_CALL,
span_replace_word,
&format!("use of `{}` followed by a function call", name),
"try this",
format!("unwrap_or_else({} panic!({}))", closure_args, sugg),
applicability,
);
return;
}
}
if name != "expect" {
return;
}
let self_type = cx.tables.expr_ty(self_expr);
let known_types = &[&paths::OPTION, &paths::RESULT];
// if not a known type, return early
if known_types.iter().all(|&k| !match_type(cx, self_type, k)) {
return;
}
if !is_call(&arg.node) {
return;
}
let closure = if match_type(cx, self_type, &paths::OPTION) {
"||"
} else {
"|_|"
};
let span_replace_word = method_span.with_hi(span.hi());
if let Some((fmt_spec, fmt_args)) = extract_format_args(arg) {
let mut applicability = Applicability::MachineApplicable;
let mut args = vec![snippet(cx, fmt_spec.span, "..").into_owned()];
args.extend(generate_format_arg_snippet(cx, fmt_args, &mut applicability));
let sugg = args.join(", ");
span_lint_and_sugg(
cx,
EXPECT_FUN_CALL,
span_replace_word,
&format!("use of `{}` followed by a function call", name),
"try this",
format!("unwrap_or_else({} panic!({}))", closure, sugg),
applicability,
);
return;
}
let mut applicability = Applicability::MachineApplicable;
let sugg: Cow<'_, _> = snippet_with_applicability(cx, arg.span, "..", &mut applicability);
span_lint_and_sugg(
cx,
EXPECT_FUN_CALL,
span_replace_word,
&format!("use of `{}` followed by a function call", name),
"try this",
format!("unwrap_or_else({} {{ let msg = {}; panic!(msg) }}))", closure, sugg),
applicability,
);
}
if args.len() == 2 {
match args[1].node {
hir::ExprKind::Lit(_) => {},
_ => check_general_case(cx, name, method_span, &args[0], &args[1], expr.span),
// If root_arg is `&'static str` or `String` we can use it directly in the `panic!` call otherwise
// we must use `to_string` to convert it.
let mut arg_root_snippet: Cow<'_, _> = snippet_with_applicability(cx, arg_root.span, "..", &mut applicability);
let arg_root_ty = cx.tables.expr_ty(arg_root);
let mut requires_conv = !match_type(cx, arg_root_ty, &paths::STRING);
if let ty::Ref(ty::ReStatic, ty, ..) = arg_root_ty.sty {
if ty.sty == ty::Str {
requires_conv = false;
}
};
if requires_conv {
arg_root_snippet.to_mut().push_str(".to_string()");
}
span_lint_and_sugg(
cx,
EXPECT_FUN_CALL,
span_replace_word,
&format!("use of `{}` followed by a function call", name),
"try this",
format!("unwrap_or_else({} {{ panic!({}) }})", closure_args, arg_root_snippet),
applicability,
);
}
/// Checks for the `CLONE_ON_COPY` lint.

84
tests/ui/expect_fun_call.fixed Normal file
View file

@ -0,0 +1,84 @@
// run-rustfix
#![warn(clippy::expect_fun_call)]
/// Checks implementation of the `EXPECT_FUN_CALL` lint
fn main() {
struct Foo;
impl Foo {
fn new() -> Self {
Foo
}
fn expect(&self, msg: &str) {
panic!("{}", msg)
}
}
let with_some = Some("value");
with_some.expect("error");
let with_none: Option<i32> = None;
with_none.expect("error");
let error_code = 123_i32;
let with_none_and_format: Option<i32> = None;
with_none_and_format.unwrap_or_else(|| panic!("Error {}: fake error", error_code));
let with_none_and_as_str: Option<i32> = None;
with_none_and_as_str.unwrap_or_else(|| panic!("Error {}: fake error", error_code));
let with_ok: Result<(), ()> = Ok(());
with_ok.expect("error");
let with_err: Result<(), ()> = Err(());
with_err.expect("error");
let error_code = 123_i32;
let with_err_and_format: Result<(), ()> = Err(());
with_err_and_format.unwrap_or_else(|_| panic!("Error {}: fake error", error_code));
let with_err_and_as_str: Result<(), ()> = Err(());
with_err_and_as_str.unwrap_or_else(|_| panic!("Error {}: fake error", error_code));
let with_dummy_type = Foo::new();
with_dummy_type.expect("another test string");
let with_dummy_type_and_format = Foo::new();
with_dummy_type_and_format.expect(&format!("Error {}: fake error", error_code));
let with_dummy_type_and_as_str = Foo::new();
with_dummy_type_and_as_str.expect(format!("Error {}: fake error", error_code).as_str());
//Issue #2937
Some("foo").unwrap_or_else(|| panic!("{} {}", 1, 2));
//Issue #2979 - this should not lint
{
let msg = "bar";
Some("foo").expect(msg);
}
{
fn get_string() -> String {
"foo".to_string()
}
fn get_static_str() -> &'static str {
"foo"
}
fn get_non_static_str(_: &u32) -> &str {
"foo"
}
Some("foo").unwrap_or_else(|| { panic!(get_string()) });
Some("foo").unwrap_or_else(|| { panic!(get_string()) });
Some("foo").unwrap_or_else(|| { panic!(get_string()) });
Some("foo").unwrap_or_else(|| { panic!(get_static_str()) });
Some("foo").unwrap_or_else(|| { panic!(get_non_static_str(&0).to_string()) });
}
}

42
tests/ui/expect_fun_call.rs
View file

@ -1,9 +1,10 @@
// run-rustfix
#![warn(clippy::expect_fun_call)]
#![allow(clippy::useless_format)]
/// Checks implementation of the `EXPECT_FUN_CALL` lint
fn expect_fun_call() {
fn main() {
struct Foo;
impl Foo {
@ -51,14 +52,33 @@ fn expect_fun_call() {
let with_dummy_type_and_as_str = Foo::new();
with_dummy_type_and_as_str.expect(format!("Error {}: fake error", error_code).as_str());
//Issue #2979 - this should not lint
let msg = "bar";
Some("foo").expect(msg);
Some("foo").expect({ &format!("error") });
Some("foo").expect(format!("error").as_ref());
//Issue #2937
Some("foo").expect(format!("{} {}", 1, 2).as_ref());
}
fn main() {}
//Issue #2979 - this should not lint
{
let msg = "bar";
Some("foo").expect(msg);
}
{
fn get_string() -> String {
"foo".to_string()
}
fn get_static_str() -> &'static str {
"foo"
}
fn get_non_static_str(_: &u32) -> &str {
"foo"
}
Some("foo").expect(&get_string());
Some("foo").expect(get_string().as_ref());
Some("foo").expect(get_string().as_str());
Some("foo").expect(get_static_str());
Some("foo").expect(get_non_static_str(&0));
}
}

54
tests/ui/expect_fun_call.stderr
View file

@ -1,5 +1,5 @@
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:27:26
--> $DIR/expect_fun_call.rs:28:26
|
LL | with_none_and_format.expect(&format!("Error {}: fake error", error_code));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!("Error {}: fake error", error_code))`
@ -7,40 +7,58 @@ LL | with_none_and_format.expect(&format!("Error {}: fake error", error_code
= note: `-D clippy::expect-fun-call` implied by `-D warnings`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:30:26
--> $DIR/expect_fun_call.rs:31:26
|
LL | with_none_and_as_str.expect(format!("Error {}: fake error", error_code).as_str());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!("Error {}: fake error", error_code))`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:40:25
--> $DIR/expect_fun_call.rs:41:25
|
LL | with_err_and_format.expect(&format!("Error {}: fake error", error_code));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| panic!("Error {}: fake error", error_code))`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:43:25
--> $DIR/expect_fun_call.rs:44:25
|
LL | with_err_and_as_str.expect(format!("Error {}: fake error", error_code).as_str());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| panic!("Error {}: fake error", error_code))`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:58:17
|
LL | Some("foo").expect({ &format!("error") });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { let msg = { &format!("error") }; panic!(msg) }))`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:59:17
|
LL | Some("foo").expect(format!("error").as_ref());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!("error"))`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:61:17
--> $DIR/expect_fun_call.rs:56:17
|
LL | Some("foo").expect(format!("{} {}", 1, 2).as_ref());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!("{} {}", 1, 2))`
error: aborting due to 7 previous errors
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:77:21
|
LL | Some("foo").expect(&get_string());
| ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:78:21
|
LL | Some("foo").expect(get_string().as_ref());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:79:21
|
LL | Some("foo").expect(get_string().as_str());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:81:21
|
LL | Some("foo").expect(get_static_str());
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_static_str()) })`
error: use of `expect` followed by a function call
--> $DIR/expect_fun_call.rs:82:21
|
LL | Some("foo").expect(get_non_static_str(&0));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_non_static_str(&0).to_string()) })`
error: aborting due to 10 previous errors