fix FN on unsuffixed floats that don't end with .

Author: ada4a

clippy_lints/src/needless_parens_on_range_literals.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::source::snippet_with_applicability;
+use clippy_utils::source::{SpanRangeExt, snippet_with_applicability};
 
 use rustc_ast::{Expr, ExprKind};
 use rustc_errors::Applicability;
@@ -41,9 +41,16 @@ declare_lint_pass!(NeedlessParensOnRangeLiterals => [NEEDLESS_PARENS_ON_RANGE_LI
 fn check_for_parens(cx: &EarlyContext<'_>, e: &Expr, is_start: bool) {
     if let ExprKind::Paren(literal) = &e.kind
         && let ExprKind::Lit(lit) = &literal.kind
-        // don't check floating point literals on the start expression of a range
-        && !(is_start && lit.kind == rustc_ast::token::LitKind::Float && lit.suffix.is_none())
     {
+        if is_start
+            && lit.kind == rustc_ast::token::LitKind::Float
+            && lit.suffix.is_none()
+            && literal.span.check_source_text(cx, |s| s.ends_with('.'))
+        {
+            // don't lint `(2.)..end`, since removing the parens would result in invalid syntax
+            return;
+        }
+
         let mut applicability = Applicability::MachineApplicable;
         let suggestion = snippet_with_applicability(cx, literal.span, "_", &mut applicability);
         span_lint_and_sugg(

tests/ui/needless_parens_on_range_literals.fixed

@@ -7,9 +7,13 @@ fn main() {
     //~| needless_parens_on_range_literals
     let _ = 'a'..'z';
     //~^ needless_parens_on_range_literals
+
     let _ = (1.)..2.;
     let _ = (1.)..2.;
     //~^ needless_parens_on_range_literals
+    let _ = 1.0..2.;
+    //~^ needless_parens_on_range_literals
+
     let _ = 'a'..;
     //~^ needless_parens_on_range_literals
     let _ = ..'z';

tests/ui/needless_parens_on_range_literals.rs

@@ -7,9 +7,13 @@ fn main() {
     //~| needless_parens_on_range_literals
     let _ = 'a'..('z');
     //~^ needless_parens_on_range_literals
+
     let _ = (1.)..2.;
     let _ = (1.)..(2.);
     //~^ needless_parens_on_range_literals
+    let _ = (1.0)..2.;
+    //~^ needless_parens_on_range_literals
+
     let _ = ('a')..;
     //~^ needless_parens_on_range_literals
     let _ = ..('z');

tests/ui/needless_parens_on_range_literals.stderr

@@ -20,22 +20,28 @@ LL |     let _ = 'a'..('z');
    |                  ^^^^^ help: try: `'z'`
 
 error: needless parenthesis on range literals can be removed
-  --> tests/ui/needless_parens_on_range_literals.rs:11:19
+  --> tests/ui/needless_parens_on_range_literals.rs:12:19
    |
 LL |     let _ = (1.)..(2.);
    |                   ^^^^ help: try: `2.`
 
 error: needless parenthesis on range literals can be removed
-  --> tests/ui/needless_parens_on_range_literals.rs:13:13
+  --> tests/ui/needless_parens_on_range_literals.rs:14:13
+   |
+LL |     let _ = (1.0)..2.;
+   |             ^^^^^ help: try: `1.0`
+
+error: needless parenthesis on range literals can be removed
+  --> tests/ui/needless_parens_on_range_literals.rs:17:13
    |
 LL |     let _ = ('a')..;
    |             ^^^^^ help: try: `'a'`
 
 error: needless parenthesis on range literals can be removed
-  --> tests/ui/needless_parens_on_range_literals.rs:15:15
+  --> tests/ui/needless_parens_on_range_literals.rs:19:15
    |
 LL |     let _ = ..('z');
    |               ^^^^^ help: try: `'z'`
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors