fix: single_range_in_vec_init wrongly unmangles macros

Author: profetia

clippy_lints/src/single_range_in_vec_init.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::higher::VecArgs;
 use clippy_utils::macros::root_macro_call_first_node;
-use clippy_utils::source::SpanRangeExt;
+use clippy_utils::source::{SpanRangeExt, snippet_with_context};
 use clippy_utils::ty::implements_trait;
 use clippy_utils::{is_no_std_crate, sym};
 use rustc_ast::{LitIntType, LitKind, UintTy};
@@ -96,9 +96,11 @@ impl LateLintPass<'_> for SingleRangeInVecInit {
             // `is_from_proc_macro` will skip any `vec![]`. Let's not!
             && snippet.starts_with(suggested_type.starts_with())
             && snippet.ends_with(suggested_type.ends_with())
-            && let Some(start_snippet) = start.expr.span.get_source_text(cx)
-            && let Some(end_snippet) = end.expr.span.get_source_text(cx)
         {
+            let mut applicability = Applicability::MaybeIncorrect;
+            let (start_snippet, _) = snippet_with_context(cx, start.expr.span, span.ctxt(), "..", &mut applicability);
+            let (end_snippet, _) = snippet_with_context(cx, end.expr.span, span.ctxt(), "..", &mut applicability);
+
             let should_emit_every_value = if let Some(step_def_id) = cx.tcx.get_diagnostic_item(sym::range_step)
                 && implements_trait(cx, ty, step_def_id, &[])
             {

tests/ui/single_range_in_vec_init.rs

@@ -73,3 +73,14 @@ fn issue16042() {
     let input = vec![Range { start: 0, end: 5 }];
     //~^ single_range_in_vec_init
 }
+
+fn issue16044() {
+    macro_rules! as_i32 {
+        ($x:expr) => {
+            $x as i32
+        };
+    }
+
+    let input = vec![0..as_i32!(10)];
+    //~^ single_range_in_vec_init
+}

tests/ui/single_range_in_vec_init.stderr

@@ -177,5 +177,17 @@ LL -     let input = vec![Range { start: 0, end: 5 }];
 LL +     let input = vec![0; 5];
    |
 
-error: aborting due to 11 previous errors
+error: a `Vec` of `Range` that is only one element
+  --> tests/ui/single_range_in_vec_init.rs:84:17
+   |
+LL |     let input = vec![0..as_i32!(10)];
+   |                 ^^^^^^^^^^^^^^^^^^^^
+   |
+help: if you wanted a `Vec` that contains the entire range, try
+   |
+LL -     let input = vec![0..as_i32!(10)];
+LL +     let input = (0..as_i32!(10)).collect::<std::vec::Vec<i32>>();
+   |
+
+error: aborting due to 12 previous errors