diff --git a/tests/ui/const_is_empty.rs b/tests/ui/const_is_empty.rs
index bd7e3a7c5d5b..f3fd84250f81 100644
--- a/tests/ui/const_is_empty.rs
+++ b/tests/ui/const_is_empty.rs
@@ -1,4 +1,5 @@
 #![warn(clippy::const_is_empty)]
+#![allow(clippy::needless_late_init, unused_must_use)]
 
 fn test_literal() {
     if "".is_empty() {
@@ -99,3 +100,40 @@ fn main() {
     let _ = b"".is_empty();
     //~^ ERROR: this expression always evaluates to true
 }
+
+fn str_from_arg(var: &str) {
+    var.is_empty();
+    // Do not lint, we know nothiny about var
+}
+
+fn update_str() {
+    let mut value = "duck";
+    value = "penguin";
+
+    let _ = value.is_empty();
+    // Do not lint since value is mutable
+}
+
+fn macros() {
+    // Content from Macro
+    let file = include_str!("const_is_empty.rs");
+    let _ = file.is_empty();
+    // No lint because initializer comes from a macro result
+
+    let var = env!("PATH");
+    let _ = var.is_empty();
+    // No lint because initializer comes from a macro result
+}
+
+fn conditional_value() {
+    let value;
+
+    if true {
+        value = "hey";
+    } else {
+        value = "hej";
+    }
+
+    let _ = value.is_empty();
+    // Do not lint, current constant folding is too simple to detect this
+}
diff --git a/tests/ui/const_is_empty.stderr b/tests/ui/const_is_empty.stderr
index ef5aa556e6a0..138f2d1340a5 100644
--- a/tests/ui/const_is_empty.stderr
+++ b/tests/ui/const_is_empty.stderr
@@ -1,5 +1,5 @@
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:4:8
+  --> tests/ui/const_is_empty.rs:5:8
    |
 LL |     if "".is_empty() {
    |        ^^^^^^^^^^^^^
@@ -8,145 +8,145 @@ LL |     if "".is_empty() {
    = help: to override `-D warnings` add `#[allow(clippy::const_is_empty)]`
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:7:8
+  --> tests/ui/const_is_empty.rs:8:8
    |
 LL |     if "foobar".is_empty() {
    |        ^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:13:8
+  --> tests/ui/const_is_empty.rs:14:8
    |
 LL |     if b"".is_empty() {
    |        ^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:16:8
+  --> tests/ui/const_is_empty.rs:17:8
    |
 LL |     if b"foobar".is_empty() {
    |        ^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:33:8
+  --> tests/ui/const_is_empty.rs:34:8
    |
 LL |     if empty2.is_empty() {
    |        ^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:36:8
+  --> tests/ui/const_is_empty.rs:37:8
    |
 LL |     if non_empty2.is_empty() {
    |        ^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:58:13
+  --> tests/ui/const_is_empty.rs:59:13
    |
 LL |     let _ = EMPTY_STR.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:60:13
+  --> tests/ui/const_is_empty.rs:61:13
    |
 LL |     let _ = NON_EMPTY_STR.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:62:13
+  --> tests/ui/const_is_empty.rs:63:13
    |
 LL |     let _ = EMPTY_BSTR.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:64:13
+  --> tests/ui/const_is_empty.rs:65:13
    |
 LL |     let _ = NON_EMPTY_BSTR.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:66:13
+  --> tests/ui/const_is_empty.rs:67:13
    |
 LL |     let _ = EMPTY_ARRAY.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:68:13
+  --> tests/ui/const_is_empty.rs:69:13
    |
 LL |     let _ = EMPTY_ARRAY_REPEAT.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:70:13
+  --> tests/ui/const_is_empty.rs:71:13
    |
 LL |     let _ = EMPTY_U8_SLICE.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:72:13
+  --> tests/ui/const_is_empty.rs:73:13
    |
 LL |     let _ = NON_EMPTY_U8_SLICE.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:74:13
+  --> tests/ui/const_is_empty.rs:75:13
    |
 LL |     let _ = NON_EMPTY_ARRAY.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:76:13
+  --> tests/ui/const_is_empty.rs:77:13
    |
 LL |     let _ = NON_EMPTY_ARRAY_REPEAT.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:78:13
+  --> tests/ui/const_is_empty.rs:79:13
    |
 LL |     let _ = EMPTY_REF_ARRAY.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:80:13
+  --> tests/ui/const_is_empty.rs:81:13
    |
 LL |     let _ = NON_EMPTY_REF_ARRAY.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:82:13
+  --> tests/ui/const_is_empty.rs:83:13
    |
 LL |     let _ = EMPTY_SLICE.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:84:13
+  --> tests/ui/const_is_empty.rs:85:13
    |
 LL |     let _ = NON_EMPTY_SLICE.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:86:13
+  --> tests/ui/const_is_empty.rs:87:13
    |
 LL |     let _ = NON_EMPTY_SLICE_REPEAT.is_empty();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:92:13
+  --> tests/ui/const_is_empty.rs:93:13
    |
 LL |     let _ = value.is_empty();
    |             ^^^^^^^^^^^^^^^^
 
 error: this expression always evaluates to false
-  --> tests/ui/const_is_empty.rs:95:13
+  --> tests/ui/const_is_empty.rs:96:13
    |
 LL |     let _ = x.is_empty();
    |             ^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:97:13
+  --> tests/ui/const_is_empty.rs:98:13
    |
 LL |     let _ = "".is_empty();
    |             ^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:99:13
+  --> tests/ui/const_is_empty.rs:100:13
    |
 LL |     let _ = b"".is_empty();
    |             ^^^^^^^^^^^^^^