remove function body from "too many args" span

clippy_lints/src/functions.rs

@@ -1,4 +1,6 @@
-use crate::utils::{iter_input_pats, snippet, span_lint, type_is_unsafe_function};
+use std::convert::TryFrom;
+
+use crate::utils::{iter_input_pats, snippet, snippet_opt, span_lint, type_is_unsafe_function};
 use matches::matches;
 use rustc::hir;
 use rustc::hir::def::Def;
@@ -8,7 +10,7 @@ use rustc::ty;
 use rustc::{declare_tool_lint, impl_lint_pass};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_target::spec::abi::Abi;
-use syntax::source_map::Span;
+use syntax::source_map::{BytePos, Span};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for functions with too many parameters.
@@ -162,6 +164,19 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
 
 impl<'a, 'tcx> Functions {
     fn check_arg_number(self, cx: &LateContext<'_, '_>, decl: &hir::FnDecl, span: Span) {
+        // Remove the function body from the span. We can't use `SourceMap::def_span` because the
+        // argument list might span multiple lines.
+        let span = if let Some(snippet) = snippet_opt(cx, span) {
+            let snippet = snippet.split('{').nth(0).unwrap_or("").trim_end();
+            if snippet.is_empty() {
+                span
+            } else {
+                span.with_hi(BytePos(span.lo().0 + u32::try_from(snippet.len()).unwrap()))
+            }
+        } else {
+            span
+        };
+
         let args = decl.inputs.len() as u64;
         if args > self.threshold {
             span_lint(

tests/ui/functions.rs

@@ -7,6 +7,26 @@ fn good(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32,
 
 fn bad(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ()) {}
 
+#[rustfmt::skip]
+fn bad_multiline(
+    one: u32,
+    two: u32,
+    three: &str,
+    four: bool,
+    five: f32,
+    six: f32,
+    seven: bool,
+    eight: ()
+) {
+    let _one = one;
+    let _two = two;
+    let _three = three;
+    let _four = four;
+    let _five = five;
+    let _six = six;
+    let _seven = seven;
+}
+
 // don't lint extern fns
 extern "C" fn extern_fn(
     _one: u32,

tests/ui/functions.stderr

@@ -2,24 +2,36 @@ error: this function has too many arguments (8/7)
   --> $DIR/functions.rs:8:1
    |
 LL | fn bad(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ()) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::too-many-arguments` implied by `-D warnings`
 
 error: this function has too many arguments (8/7)
-  --> $DIR/functions.rs:25:5
+  --> $DIR/functions.rs:11:1
+   |
+LL | / fn bad_multiline(
+LL | |     one: u32,
+LL | |     two: u32,
+LL | |     three: &str,
+...  |
+LL | |     eight: ()
+LL | | ) {
+   | |_^
+
+error: this function has too many arguments (8/7)
+  --> $DIR/functions.rs:45:5
    |
 LL |     fn bad(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this function has too many arguments (8/7)
-  --> $DIR/functions.rs:34:5
+  --> $DIR/functions.rs:54:5
    |
 LL |     fn bad_method(_one: u32, _two: u32, _three: &str, _four: bool, _five: f32, _six: f32, _seven: bool, _eight: ()) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:43:34
+  --> $DIR/functions.rs:63:34
    |
 LL |         println!("{}", unsafe { *p });
    |                                  ^
@@ -27,52 +39,52 @@ LL |         println!("{}", unsafe { *p });
    = note: `-D clippy::not-unsafe-ptr-arg-deref` implied by `-D warnings`
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:44:35
+  --> $DIR/functions.rs:64:35
    |
 LL |         println!("{:?}", unsafe { p.as_ref() });
    |                                   ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:45:33
+  --> $DIR/functions.rs:65:33
    |
 LL |         unsafe { std::ptr::read(p) };
    |                                 ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:56:30
+  --> $DIR/functions.rs:76:30
    |
 LL |     println!("{}", unsafe { *p });
    |                              ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:57:31
+  --> $DIR/functions.rs:77:31
    |
 LL |     println!("{:?}", unsafe { p.as_ref() });
    |                               ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:58:29
+  --> $DIR/functions.rs:78:29
    |
 LL |     unsafe { std::ptr::read(p) };
    |                             ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:67:34
+  --> $DIR/functions.rs:87:34
    |
 LL |         println!("{}", unsafe { *p });
    |                                  ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:68:35
+  --> $DIR/functions.rs:88:35
    |
 LL |         println!("{:?}", unsafe { p.as_ref() });
    |                                   ^
 
 error: this public function dereferences a raw pointer but is not marked `unsafe`
-  --> $DIR/functions.rs:69:33
+  --> $DIR/functions.rs:89:33
    |
 LL |         unsafe { std::ptr::read(p) };
    |                                 ^
 
-error: aborting due to 12 previous errors
+error: aborting due to 13 previous errors