Add edge case with env! arg to test and known problems

clippy_lints/src/print.rs

@@ -84,6 +84,9 @@ declare_clippy_lint! {
 /// (c.f., https://github.com/matthiaskrgr/rust-str-bench) and unnecessary
 /// (i.e., just put the literal in the format string)
 ///
+/// **Known problems:** Will also warn with macro calls as arguments that expand to literals
+/// -- e.g., `println!("{}", env!("FOO"))`.
+///
 /// **Example:**
 /// ```rust
 /// println!("{}", "foo");

tests/ui/print_literal.rs

@@ -10,6 +10,12 @@ fn main() {
     println!("Hello {}", world);
     println!("3 in hex is {:X}", 3);
 
+    // this in theory shouldn't yield a warning,
+    // but at present time, it's a known edge case
+    // that isn't handled (because we can't expand
+    // `println!` and not `env!`)
+    println!("foo: {}", env!("BAR"));
+
     // these should throw warnings
     print!("Hello {}", "world");
     println!("Hello {} {}", world, "world");

tests/ui/print_literal.stderr

@@ -1,100 +1,106 @@
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:14:24
+  --> $DIR/print_literal.rs:17:25
    |
-14 |     print!("Hello {}", "world");
-   |                        ^^^^^^^
+17 |     println!("foo: {}", env!("BAR"));
+   |                         ^^^^^^^^^^^
    |
    = note: `-D print-literal` implied by `-D warnings`
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:15:36
+  --> $DIR/print_literal.rs:20:24
    |
-15 |     println!("Hello {} {}", world, "world");
+20 |     print!("Hello {}", "world");
+   |                        ^^^^^^^
+
+error: printing a literal with an empty format string
+  --> $DIR/print_literal.rs:21:36
+   |
+21 |     println!("Hello {} {}", world, "world");
    |                                    ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:16:26
+  --> $DIR/print_literal.rs:22:26
    |
-16 |     println!("Hello {}", "world");
+22 |     println!("Hello {}", "world");
    |                          ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:17:30
+  --> $DIR/print_literal.rs:23:30
    |
-17 |     println!("10 / 4 is {}", 2.5);
+23 |     println!("10 / 4 is {}", 2.5);
    |                              ^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:18:28
+  --> $DIR/print_literal.rs:24:28
    |
-18 |     println!("2 + 1 = {}", 3);
+24 |     println!("2 + 1 = {}", 3);
    |                            ^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:19:31
+  --> $DIR/print_literal.rs:25:31
    |
-19 |     println!("2 + 1 = {:.4}", 3);
+25 |     println!("2 + 1 = {:.4}", 3);
    |                               ^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:20:32
+  --> $DIR/print_literal.rs:26:32
    |
-20 |     println!("2 + 1 = {:5.4}", 3);
+26 |     println!("2 + 1 = {:5.4}", 3);
    |                                ^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:21:33
+  --> $DIR/print_literal.rs:27:33
    |
-21 |     println!("Debug test {:?}", "hello, world");
+27 |     println!("Debug test {:?}", "hello, world");
    |                                 ^^^^^^^^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:26:25
+  --> $DIR/print_literal.rs:32:25
    |
-26 |     println!("{0} {1}", "hello", "world");
+32 |     println!("{0} {1}", "hello", "world");
    |                         ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:26:34
+  --> $DIR/print_literal.rs:32:34
    |
-26 |     println!("{0} {1}", "hello", "world");
+32 |     println!("{0} {1}", "hello", "world");
    |                                  ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:27:25
+  --> $DIR/print_literal.rs:33:25
    |
-27 |     println!("{1} {0}", "hello", "world");
+33 |     println!("{1} {0}", "hello", "world");
    |                         ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:27:34
+  --> $DIR/print_literal.rs:33:34
    |
-27 |     println!("{1} {0}", "hello", "world");
+33 |     println!("{1} {0}", "hello", "world");
    |                                  ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:30:33
+  --> $DIR/print_literal.rs:36:33
    |
-30 |     println!("{foo} {bar}", foo="hello", bar="world");
+36 |     println!("{foo} {bar}", foo="hello", bar="world");
    |                                 ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:30:46
+  --> $DIR/print_literal.rs:36:46
    |
-30 |     println!("{foo} {bar}", foo="hello", bar="world");
+36 |     println!("{foo} {bar}", foo="hello", bar="world");
    |                                              ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:31:33
+  --> $DIR/print_literal.rs:37:33
    |
-31 |     println!("{bar} {foo}", foo="hello", bar="world");
+37 |     println!("{bar} {foo}", foo="hello", bar="world");
    |                                 ^^^^^^^
 
 error: printing a literal with an empty format string
-  --> $DIR/print_literal.rs:31:46
+  --> $DIR/print_literal.rs:37:46
    |
-31 |     println!("{bar} {foo}", foo="hello", bar="world");
+37 |     println!("{bar} {foo}", foo="hello", bar="world");
    |                                              ^^^^^^^
 
-error: aborting due to 16 previous errors
+error: aborting due to 17 previous errors