don't check if from macro invocation

clippy_lints/src/strings.rs

@@ -253,6 +253,10 @@ impl<'tcx> LateLintPass<'tcx> for StringLitAsBytes {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
         use rustc_ast::LitKind;
 
+        if e.span.from_expansion() {
+            return;
+        }
+
         if_chain! {
             // Find std::str::converts::from_utf8
             if let Some(args) = match_function_call(cx, e, &paths::STR_FROM_UTF8);

tests/ui/string_lit_as_bytes.fixed

@@ -3,6 +3,12 @@
 #![allow(dead_code, unused_variables)]
 #![warn(clippy::string_lit_as_bytes)]
 
+macro_rules! b {
+    ($b:literal) => {
+        const C: &[u8] = $b.as_bytes();
+    }
+}
+
 fn str_lit_as_bytes() {
     let bs = b"hello there";
 
@@ -11,6 +17,8 @@ fn str_lit_as_bytes() {
     let bs = b"lit to string".to_vec();
     let bs = b"lit to owned".to_vec();
 
+    b!("aaa");
+
     // no warning, because these cannot be written as byte string literals:
     let ubs = "☃".as_bytes();
     let ubs = "hello there! this is a very long string".as_bytes();

tests/ui/string_lit_as_bytes.rs

@@ -3,6 +3,12 @@
 #![allow(dead_code, unused_variables)]
 #![warn(clippy::string_lit_as_bytes)]
 
+macro_rules! b {
+    ($b:literal) => {
+        const C: &[u8] = $b.as_bytes();
+    }
+}
+
 fn str_lit_as_bytes() {
     let bs = "hello there".as_bytes();
 
@@ -11,6 +17,8 @@ fn str_lit_as_bytes() {
     let bs = "lit to string".to_string().into_bytes();
     let bs = "lit to owned".to_owned().into_bytes();
 
+    b!("aaa");
+
     // no warning, because these cannot be written as byte string literals:
     let ubs = "☃".as_bytes();
     let ubs = "hello there! this is a very long string".as_bytes();

tests/ui/string_lit_as_bytes.stderr

@@ -1,5 +1,5 @@
 error: calling `as_bytes()` on a string literal
-  --> $DIR/string_lit_as_bytes.rs:7:14
+  --> $DIR/string_lit_as_bytes.rs:13:14
    |
 LL |     let bs = "hello there".as_bytes();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `b"hello there"`
@@ -7,31 +7,31 @@ LL |     let bs = "hello there".as_bytes();
    = note: `-D clippy::string-lit-as-bytes` implied by `-D warnings`
 
 error: calling `as_bytes()` on a string literal
-  --> $DIR/string_lit_as_bytes.rs:9:14
+  --> $DIR/string_lit_as_bytes.rs:15:14
    |
 LL |     let bs = r###"raw string with 3# plus " ""###.as_bytes();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `br###"raw string with 3# plus " ""###`
 
 error: calling `into_bytes()` on a string literal
-  --> $DIR/string_lit_as_bytes.rs:11:14
+  --> $DIR/string_lit_as_bytes.rs:17:14
    |
 LL |     let bs = "lit to string".to_string().into_bytes();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `b"lit to string".to_vec()`
 
 error: calling `into_bytes()` on a string literal
-  --> $DIR/string_lit_as_bytes.rs:12:14
+  --> $DIR/string_lit_as_bytes.rs:18:14
    |
 LL |     let bs = "lit to owned".to_owned().into_bytes();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `b"lit to owned".to_vec()`
 
 error: calling `as_bytes()` on `include_str!(..)`
-  --> $DIR/string_lit_as_bytes.rs:25:22
+  --> $DIR/string_lit_as_bytes.rs:33:22
    |
 LL |     let includestr = include_str!("string_lit_as_bytes.rs").as_bytes();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `include_bytes!(..)` instead: `include_bytes!("string_lit_as_bytes.rs")`
 
 error: calling `as_bytes()` on a string literal
-  --> $DIR/string_lit_as_bytes.rs:27:13
+  --> $DIR/string_lit_as_bytes.rs:35:13
    |
 LL |     let _ = "string with newline/t/n".as_bytes();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using a byte string literal instead: `b"string with newline/t/n"`