11use rustc:: hir:: * ;
2- use rustc:: hir:: map:: Node :: NodeItem ;
32use rustc:: lint:: * ;
43use rustc:: ty;
54use syntax:: ast:: LitKind ;
6- use syntax:: symbol:: InternedString ;
75use utils:: paths;
86use utils:: { is_expn_of, match_def_path, match_type, resolve_node, span_lint, walk_ptrs_ty, opt_def_id} ;
97
@@ -50,8 +48,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
5048 let Some ( fun_def_id) = opt_def_id( resolve_node( cx, qpath, fun. hir_id) ) ,
5149 match_def_path( cx. tcx, fun_def_id, & paths:: FMT_ARGUMENTS_NEWV1 ) ,
5250 // ensure the format string is `"{..}"` with only one argument and no text
53- check_static_str( cx , & args[ 0 ] ) ,
51+ check_static_str( & args[ 0 ] ) ,
5452 // ensure the format argument is `{}` ie. Display with no fancy option
53+ // and that the argument is a string
5554 check_arg_is_display( cx, & args[ 1 ] )
5655 ] , {
5756 span_lint( cx, USELESS_FORMAT , span, "useless use of `format!`" ) ;
@@ -69,44 +68,19 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
6968 }
7069}
7170
72- /// Returns the slice of format string parts in an `Arguments::new_v1` call.
73- /// Public because it's shared with a lint in print.rs.
74- pub fn get_argument_fmtstr_parts < ' a , ' b > ( cx : & LateContext < ' a , ' b > , expr : & ' a Expr ) -> Option < Vec < InternedString > > {
71+ /// Checks if the expressions matches `&[""]`
72+ fn check_static_str ( expr : & Expr ) -> bool {
7573 if_let_chain ! { [
76- let ExprBlock ( ref block) = expr. node,
77- block. stmts. len( ) == 1 ,
78- let StmtDecl ( ref decl, _) = block. stmts[ 0 ] . node,
79- let DeclItem ( ref decl) = decl. node,
80- let Some ( NodeItem ( decl) ) = cx. tcx. hir. find( decl. id) ,
81- decl. name == "__STATIC_FMTSTR" ,
82- let ItemStatic ( _, _, ref expr) = decl. node,
83- let ExprAddrOf ( _, ref expr) = cx. tcx. hir. body( * expr) . value. node, // &["…", "…", …]
84- let ExprArray ( ref exprs) = expr. node,
74+ let ExprAddrOf ( _, ref expr) = expr. node, // &[""]
75+ let ExprArray ( ref exprs) = expr. node, // [""]
76+ exprs. len( ) == 1 ,
77+ let ExprLit ( ref lit) = exprs[ 0 ] . node,
78+ let LitKind :: Str ( ref lit, _) = lit. node,
8579 ] , {
86- let mut result = Vec :: new( ) ;
87- for expr in exprs {
88- if let ExprLit ( ref lit) = expr. node {
89- if let LitKind :: Str ( ref lit, _) = lit. node {
90- result. push( lit. as_str( ) ) ;
91- }
92- }
93- }
94- return Some ( result) ;
80+ return lit. as_str( ) . is_empty( ) ;
9581 } }
96- None
97- }
9882
99- /// Checks if the expressions matches
100- /// ```rust, ignore
101- /// { static __STATIC_FMTSTR: &'static[&'static str] = &["a", "b", c];
102- /// __STATIC_FMTSTR }
103- /// ```
104- fn check_static_str ( cx : & LateContext , expr : & Expr ) -> bool {
105- if let Some ( expr) = get_argument_fmtstr_parts ( cx, expr) {
106- expr. len ( ) == 1 && expr[ 0 ] . is_empty ( )
107- } else {
108- false
109- }
83+ false
11084}
11185
11286/// Checks if the expressions matches
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