Fix almost_complete_letter_range false positive.

clippy_lints/src/almost_complete_letter_range.rs

@@ -4,6 +4,7 @@ use clippy_utils::{meets_msrv, msrvs};
 use rustc_ast::ast::{Expr, ExprKind, LitKind, Pat, PatKind, RangeEnd, RangeLimits};
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_semver::RustcVersion;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::Span;
@@ -79,6 +80,7 @@ fn check_range(cx: &EarlyContext<'_>, span: Span, start: &Expr, end: &Expr, sugg
             (LitKind::Byte(b'a') | LitKind::Char('a'), LitKind::Byte(b'z') | LitKind::Char('z'))
             | (LitKind::Byte(b'A') | LitKind::Char('A'), LitKind::Byte(b'Z') | LitKind::Char('Z'))
         )
+        && !in_external_macro(cx.sess(), span)
     {
         span_lint_and_then(
             cx,

tests/ui/almost_complete_letter_range.fixed

@@ -1,5 +1,6 @@
 // run-rustfix
 // edition:2018
+// aux-build:macro_rules.rs
 
 #![feature(custom_inner_attributes)]
 #![feature(exclusive_range_pattern)]
@@ -8,12 +9,21 @@
 #![allow(ellipsis_inclusive_range_patterns)]
 #![allow(clippy::needless_parens_on_range_literals)]
 
+#[macro_use]
+extern crate macro_rules;
+
 macro_rules! a {
     () => {
         'a'
     };
 }
 
+macro_rules! b {
+    () => {
+        let _ = 'a'..='z';
+    };
+}
+
 fn main() {
     #[rustfmt::skip]
     {
@@ -47,6 +57,9 @@ fn main() {
         'B'..'Z' => 4,
         _ => 5,
     };
+
+    almost_complete_letter_range!();
+    b!();
 }
 
 fn _under_msrv() {

tests/ui/almost_complete_letter_range.rs

@@ -1,5 +1,6 @@
 // run-rustfix
 // edition:2018
+// aux-build:macro_rules.rs
 
 #![feature(custom_inner_attributes)]
 #![feature(exclusive_range_pattern)]
@@ -8,12 +9,21 @@
 #![allow(ellipsis_inclusive_range_patterns)]
 #![allow(clippy::needless_parens_on_range_literals)]
 
+#[macro_use]
+extern crate macro_rules;
+
 macro_rules! a {
     () => {
         'a'
     };
 }
 
+macro_rules! b {
+    () => {
+        let _ = 'a'..'z';
+    };
+}
+
 fn main() {
     #[rustfmt::skip]
     {
@@ -47,6 +57,9 @@ fn main() {
         'B'..'Z' => 4,
         _ => 5,
     };
+
+    almost_complete_letter_range!();
+    b!();
 }
 
 fn _under_msrv() {

tests/ui/almost_complete_letter_range.stderr

@@ -1,5 +1,5 @@
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:20:17
+  --> $DIR/almost_complete_letter_range.rs:30:17
    |
 LL |         let _ = ('a') ..'z';
    |                 ^^^^^^--^^^
@@ -9,92 +9,105 @@ LL |         let _ = ('a') ..'z';
    = note: `-D clippy::almost-complete-letter-range` implied by `-D warnings`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:21:17
+  --> $DIR/almost_complete_letter_range.rs:31:17
    |
 LL |         let _ = 'A' .. ('Z');
    |                 ^^^^--^^^^^^
    |                     |
    |                     help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:27:13
+  --> $DIR/almost_complete_letter_range.rs:37:13
    |
 LL |     let _ = (b'a')..(b'z');
    |             ^^^^^^--^^^^^^
    |                   |
    |                   help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:28:13
+  --> $DIR/almost_complete_letter_range.rs:38:13
    |
 LL |     let _ = b'A'..b'Z';
    |             ^^^^--^^^^
    |                 |
    |                 help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:33:13
+  --> $DIR/almost_complete_letter_range.rs:43:13
    |
 LL |     let _ = a!()..'z';
    |             ^^^^--^^^
    |                 |
    |                 help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:36:9
+  --> $DIR/almost_complete_letter_range.rs:46:9
    |
 LL |         b'a'..b'z' if true => 1,
    |         ^^^^--^^^^
    |             |
    |             help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:37:9
+  --> $DIR/almost_complete_letter_range.rs:47:9
    |
 LL |         b'A'..b'Z' if true => 2,
    |         ^^^^--^^^^
    |             |
    |             help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:44:9
+  --> $DIR/almost_complete_letter_range.rs:54:9
    |
 LL |         'a'..'z' if true => 1,
    |         ^^^--^^^
    |            |
    |            help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:45:9
+  --> $DIR/almost_complete_letter_range.rs:55:9
    |
 LL |         'A'..'Z' if true => 2,
    |         ^^^--^^^
    |            |
    |            help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:55:9
+  --> $DIR/almost_complete_letter_range.rs:23:17
+   |
+LL |         let _ = 'a'..'z';
+   |                 ^^^--^^^
+   |                    |
+   |                    help: use an inclusive range: `..=`
+...
+LL |     b!();
+   |     ---- in this macro invocation
+   |
+   = note: this error originates in the macro `b` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: almost complete ascii letter range
+  --> $DIR/almost_complete_letter_range.rs:68:9
    |
 LL |         'a'..'z' => 1,
    |         ^^^--^^^
    |            |
    |            help: use an inclusive range: `...`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:62:13
+  --> $DIR/almost_complete_letter_range.rs:75:13
    |
 LL |     let _ = 'a'..'z';
    |             ^^^--^^^
    |                |
    |                help: use an inclusive range: `..=`
 
 error: almost complete ascii letter range
-  --> $DIR/almost_complete_letter_range.rs:64:9
+  --> $DIR/almost_complete_letter_range.rs:77:9
    |
 LL |         'a'..'z' => 1,
    |         ^^^--^^^
    |            |
    |            help: use an inclusive range: `..=`
 
-error: aborting due to 12 previous errors
+error: aborting due to 13 previous errors
 

tests/ui/auxiliary/macro_rules.rs

@@ -140,3 +140,10 @@ macro_rules! manual_rem_euclid {
 macro_rules! equatable_if_let {
     ($a:ident) => {{ if let 2 = $a {} }};
 }
+
+#[macro_export]
+macro_rules! almost_complete_letter_range {
+    () => {
+        let _ = 'a'..'z';
+    };
+}