Merge pull request #2097 from rust-lang-nursery/fix-2041

Fix detection of format and print macros
This commit is contained in:
Martin Carton 2017-09-29 21:25:10 +02:00 committed by GitHub
commit 06280e838b
4 changed files with 72 additions and 44 deletions

View file

@ -1,9 +1,7 @@
use rustc::hir::*;
use rustc::hir::map::Node::NodeItem;
use rustc::lint::*;
use rustc::ty;
use syntax::ast::LitKind;
use syntax::symbol::InternedString;
use utils::paths;
use utils::{is_expn_of, match_def_path, match_type, resolve_node, span_lint, walk_ptrs_ty, opt_def_id};
@ -50,8 +48,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
let Some(fun_def_id) = opt_def_id(resolve_node(cx, qpath, fun.hir_id)),
match_def_path(cx.tcx, fun_def_id, &paths::FMT_ARGUMENTS_NEWV1),
// ensure the format string is `"{..}"` with only one argument and no text
check_static_str(cx, &args[0]),
check_static_str(&args[0]),
// ensure the format argument is `{}` ie. Display with no fancy option
// and that the argument is a string
check_arg_is_display(cx, &args[1])
], {
span_lint(cx, USELESS_FORMAT, span, "useless use of `format!`");
@ -69,44 +68,19 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
}
}
/// Returns the slice of format string parts in an `Arguments::new_v1` call.
/// Public because it's shared with a lint in print.rs.
pub fn get_argument_fmtstr_parts<'a, 'b>(cx: &LateContext<'a, 'b>, expr: &'a Expr) -> Option<Vec<InternedString>> {
/// Checks if the expressions matches `&[""]`
fn check_static_str(expr: &Expr) -> bool {
if_let_chain! {[
let ExprBlock(ref block) = expr.node,
block.stmts.len() == 1,
let StmtDecl(ref decl, _) = block.stmts[0].node,
let DeclItem(ref decl) = decl.node,
let Some(NodeItem(decl)) = cx.tcx.hir.find(decl.id),
decl.name == "__STATIC_FMTSTR",
let ItemStatic(_, _, ref expr) = decl.node,
let ExprAddrOf(_, ref expr) = cx.tcx.hir.body(*expr).value.node, // &["…", "…", …]
let ExprArray(ref exprs) = expr.node,
let ExprAddrOf(_, ref expr) = expr.node, // &[""]
let ExprArray(ref exprs) = expr.node, // [""]
exprs.len() == 1,
let ExprLit(ref lit) = exprs[0].node,
let LitKind::Str(ref lit, _) = lit.node,
], {
let mut result = Vec::new();
for expr in exprs {
if let ExprLit(ref lit) = expr.node {
if let LitKind::Str(ref lit, _) = lit.node {
result.push(lit.as_str());
}
}
}
return Some(result);
return lit.as_str().is_empty();
}}
None
}
/// Checks if the expressions matches
/// ```rust, ignore
/// { static __STATIC_FMTSTR: &'static[&'static str] = &["a", "b", c];
/// __STATIC_FMTSTR }
/// ```
fn check_static_str(cx: &LateContext, expr: &Expr) -> bool {
if let Some(expr) = get_argument_fmtstr_parts(cx, expr) {
expr.len() == 1 && expr[0].is_empty()
} else {
false
}
false
}
/// Checks if the expressions matches

View file

@ -1,9 +1,10 @@
use rustc::hir::*;
use rustc::hir::map::Node::{NodeImplItem, NodeItem};
use rustc::lint::*;
use utils::{paths, opt_def_id};
use syntax::ast::LitKind;
use syntax::symbol::InternedString;
use utils::{is_expn_of, match_def_path, match_path, resolve_node, span_lint};
use format::get_argument_fmtstr_parts;
use utils::{paths, opt_def_id};
/// **What it does:** This lint warns when you using `print!()` with a format
/// string that
@ -103,15 +104,14 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
let ExprTup(ref args) = args.node,
// collect the format string parts and check the last one
let Some(fmtstrs) = get_argument_fmtstr_parts(cx, &args_args[0]),
let Some(last_str) = fmtstrs.last(),
let Some('\n') = last_str.chars().last(),
let Some((fmtstr, fmtlen)) = get_argument_fmtstr_parts(&args_args[0]),
let Some('\n') = fmtstr.chars().last(),
// "foo{}bar" is made into two strings + one argument,
// if the format string starts with `{}` (eg. "{}foo"),
// the string array is prepended an empty string "".
// We only want to check the last string after any `{}`:
args.len() < fmtstrs.len(),
args.len() < fmtlen,
], {
span_lint(cx, PRINT_WITH_NEWLINE, span,
"using `print!()` with a format string that ends in a \
@ -150,3 +150,17 @@ fn is_in_debug_impl(cx: &LateContext, expr: &Expr) -> bool {
false
}
/// Returns the slice of format string parts in an `Arguments::new_v1` call.
fn get_argument_fmtstr_parts(expr: &Expr) -> Option<(InternedString, usize)> {
if_let_chain! {[
let ExprAddrOf(_, ref expr) = expr.node, // &["…", "…", …]
let ExprArray(ref exprs) = expr.node,
let Some(expr) = exprs.last(),
let ExprLit(ref lit) = expr.node,
let LitKind::Str(ref lit, _) = lit.node,
], {
return Some((lit.as_str(), exprs.len()));
}}
None
}

View file

@ -6,5 +6,17 @@ error: useless use of `format!`
|
= note: `-D useless-format` implied by `-D warnings`
error: aborting due to previous error
error: useless use of `format!`
--> $DIR/format.rs:8:5
|
8 | format!("{}", "foo");
| ^^^^^^^^^^^^^^^^^^^^^
error: useless use of `format!`
--> $DIR/format.rs:15:5
|
15 | format!("{}", arg);
| ^^^^^^^^^^^^^^^^^^^
error: aborting due to 3 previous errors

View file

@ -0,0 +1,28 @@
error: using `print!()` with a format string that ends in a newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:6:5
|
6 | print!("Hello/n");
| ^^^^^^^^^^^^^^^^^^
|
= note: `-D print-with-newline` implied by `-D warnings`
error: using `print!()` with a format string that ends in a newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:7:5
|
7 | print!("Hello {}/n", "world");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: using `print!()` with a format string that ends in a newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:8:5
|
8 | print!("Hello {} {}/n/n", "world", "#2");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: using `print!()` with a format string that ends in a newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:9:5
|
9 | print!("{}/n", 1265);
| ^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors