From e31a0941e20851933eb80b14da8d2a11b6f614b1 Mon Sep 17 00:00:00 2001
From: Devon Hollowood <devonhollowood@gmail.com>
Date: Thu, 12 Oct 2017 05:53:20 -0300
Subject: [PATCH] Fix output for write macros

---
 clippy_lints/src/suggest_print.rs | 23 +++++++++++-----------
 tests/ui/suggest_print.stderr     | 32 +++++++++++++++----------------
 2 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/clippy_lints/src/suggest_print.rs b/clippy_lints/src/suggest_print.rs
index 1bc58297476f..bf202b20057f 100644
--- a/clippy_lints/src/suggest_print.rs
+++ b/clippy_lints/src/suggest_print.rs
@@ -56,14 +56,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
                 None
             },
         ], {
-            let dest_expr = &write_args[0];
-            let (span, calling_macro) =
-                if let Some(span) = is_expn_of(dest_expr.span, "write") {
-                    (span, Some("write"))
-                } else if let Some(span) = is_expn_of(dest_expr.span, "writeln") {
-                    (span, Some("writeln"))
+            let write_span = unwrap_args[0].span;
+            let calling_macro =
+                // ordering is important here, since `writeln!` uses `write!` internally
+                if is_expn_of(write_span, "writeln").is_some() {
+                    Some("writeln")
+                } else if is_expn_of(write_span, "write").is_some() {
+                    Some("write")
                 } else {
-                    (dest_expr.span, None)
+                    None
                 };
             let prefix = if dest_name == "stderr" {
                 "e"
@@ -74,9 +75,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
                 span_lint(
                     cx,
                     SUGGEST_PRINT,
-                    span,
+                    expr.span,
                     &format!(
-                        "use of `{}!({}, ...).unwrap()`. Consider using `{}{}!` instead",
+                        "use of `{}!({}(), ...).unwrap()`. Consider using `{}{}!` instead",
                         macro_name,
                         dest_name,
                         prefix,
@@ -87,9 +88,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
                 span_lint(
                     cx,
                     SUGGEST_PRINT,
-                    span,
+                    expr.span,
                     &format!(
-                        "use of `{}.write_fmt(...).unwrap()`. Consider using `{}print!` instead",
+                        "use of `{}().write_fmt(...).unwrap()`. Consider using `{}print!` instead",
                         dest_name,
                         prefix,
                     )
diff --git a/tests/ui/suggest_print.stderr b/tests/ui/suggest_print.stderr
index f83f6cf7ad35..bae9f6f26795 100644
--- a/tests/ui/suggest_print.stderr
+++ b/tests/ui/suggest_print.stderr
@@ -1,38 +1,38 @@
-error: use of `stdout.write_fmt(...).unwrap()`. Consider using `print!` instead
-  --> $DIR/suggest_print.rs:16:16
+error: use of `write!(stdout(), ...).unwrap()`. Consider using `print!` instead
+  --> $DIR/suggest_print.rs:16:9
    |
 16 |         write!(std::io::stdout(), "test").unwrap();
-   |                ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D suggest-print` implied by `-D warnings`
 
-error: use of `stderr.write_fmt(...).unwrap()`. Consider using `eprint!` instead
-  --> $DIR/suggest_print.rs:17:16
+error: use of `write!(stderr(), ...).unwrap()`. Consider using `eprint!` instead
+  --> $DIR/suggest_print.rs:17:9
    |
 17 |         write!(std::io::stderr(), "test").unwrap();
-   |                ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: use of `stdout.write_fmt(...).unwrap()`. Consider using `print!` instead
-  --> $DIR/suggest_print.rs:18:18
+error: use of `writeln!(stdout(), ...).unwrap()`. Consider using `println!` instead
+  --> $DIR/suggest_print.rs:18:9
    |
 18 |         writeln!(std::io::stdout(), "test").unwrap();
-   |                  ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: use of `stderr.write_fmt(...).unwrap()`. Consider using `eprint!` instead
-  --> $DIR/suggest_print.rs:19:18
+error: use of `writeln!(stderr(), ...).unwrap()`. Consider using `eprintln!` instead
+  --> $DIR/suggest_print.rs:19:9
    |
 19 |         writeln!(std::io::stderr(), "test").unwrap();
-   |                  ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: use of `stdout.write_fmt(...).unwrap()`. Consider using `print!` instead
+error: use of `stdout().write_fmt(...).unwrap()`. Consider using `print!` instead
   --> $DIR/suggest_print.rs:20:9
    |
 20 |         std::io::stdout().write_fmt(format_args!("test")).unwrap();
-   |         ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: use of `stderr.write_fmt(...).unwrap()`. Consider using `eprint!` instead
+error: use of `stderr().write_fmt(...).unwrap()`. Consider using `eprint!` instead
   --> $DIR/suggest_print.rs:21:9
    |
 21 |         std::io::stderr().write_fmt(format_args!("test")).unwrap();
-   |         ^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^