Merge pull request #238 from nrc/fn-decl

Customisation of function decls

src/config.rs

@@ -11,7 +11,7 @@
 extern crate toml;
 
 use {NewlineStyle, BraceStyle, ReturnIndent, StructLitStyle};
-use lists::SeparatorTactic;
+use lists::{SeparatorTactic, ListTactic};
 use issues::ReportTactic;
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
@@ -26,6 +26,25 @@ pub enum BlockIndentStyle {
 
 impl_enum_decodable!(BlockIndentStyle, Inherit, Tabbed, Visual);
 
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub enum Density {
+    // Fit as much on one line as possible.
+    Compressed,
+    // Use more lines.
+    Tall,
+}
+
+impl_enum_decodable!(Density, Compressed, Tall);
+
+impl Density {
+    pub fn to_list_tactic(self) -> ListTactic {
+        match self {
+            Density::Compressed => ListTactic::Mixed,
+            Density::Tall => ListTactic::HorizontalVertical,
+        }
+    }
+}
+
 macro_rules! create_config {
     ($($i:ident: $ty:ty),+ $(,)*) => (
         #[derive(RustcDecodable, Clone)]
@@ -70,6 +89,14 @@ create_config! {
     fn_brace_style: BraceStyle,
     fn_return_indent: ReturnIndent,
     fn_args_paren_newline: bool,
+    fn_args_layout: Density,
+    fn_arg_indent: BlockIndentStyle,
+    where_density: Density, // Should we at least try to put the where clause on the same line as
+                            // the rest of the function decl?
+    where_indent: BlockIndentStyle, // Visual will be treated like Tabbed
+    where_layout: ListTactic,
+    where_pred_indent: BlockIndentStyle,
+    generics_indent: BlockIndentStyle,
     struct_trailing_comma: SeparatorTactic,
     struct_lit_trailing_comma: SeparatorTactic,
     struct_lit_style: StructLitStyle,
@@ -95,6 +122,13 @@ impl Default for Config {
             fn_brace_style: BraceStyle::SameLineWhere,
             fn_return_indent: ReturnIndent::WithArgs,
             fn_args_paren_newline: true,
+            fn_args_layout: Density::Tall,
+            fn_arg_indent: BlockIndentStyle::Visual,
+            where_density: Density::Tall,
+            where_indent: BlockIndentStyle::Tabbed,
+            where_layout: ListTactic::Vertical,
+            where_pred_indent: BlockIndentStyle::Visual,
+            generics_indent: BlockIndentStyle::Visual,
             struct_trailing_comma: SeparatorTactic::Vertical,
             struct_lit_trailing_comma: SeparatorTactic::Vertical,
             struct_lit_style: StructLitStyle::BlockIndent,

src/items.rs

@@ -18,7 +18,7 @@ use expr::rewrite_assign_rhs;
 use comment::FindUncommented;
 use visitor::FmtVisitor;
 use rewrite::Rewrite;
-use config::Config;
+use config::{Config, BlockIndentStyle, Density};
 
 use syntax::{ast, abi};
 use syntax::codemap::{self, Span, BytePos};
@@ -99,7 +99,7 @@ impl<'a> FmtVisitor<'a> {
                       vis: ast::Visibility,
                       span: Span)
                       -> String {
-        let newline_brace = self.newline_for_brace(&generics.where_clause);
+        let mut newline_brace = self.newline_for_brace(&generics.where_clause);
 
         let mut result = self.rewrite_fn_base(indent,
                                               ident,
@@ -113,6 +113,10 @@ impl<'a> FmtVisitor<'a> {
                                               span,
                                               newline_brace);
 
+        if self.config.fn_brace_style != BraceStyle::AlwaysNextLine && !result.contains('\n') {
+            newline_brace = false;
+        }
+
         // Prepare for the function body by possibly adding a newline and
         // indent.
         // FIXME we'll miss anything between the end of the signature and the
@@ -196,6 +200,7 @@ impl<'a> FmtVisitor<'a> {
         // Generics.
         let generics_indent = indent + result.len();
         result.push_str(&self.rewrite_generics(generics,
+                                               indent,
                                                generics_indent,
                                                codemap::mk_sp(span.lo,
                                                               span_for_return(&fd.output).lo)));
@@ -237,6 +242,7 @@ impl<'a> FmtVisitor<'a> {
                                            explicit_self,
                                            one_line_budget,
                                            multi_line_budget,
+                                           indent,
                                            arg_indent,
                                            args_span));
         result.push(')');
@@ -279,10 +285,18 @@ impl<'a> FmtVisitor<'a> {
             }
         }
 
+        let where_density = if self.config.where_density == Density::Compressed &&
+                               !result.contains('\n') {
+            Density::Compressed
+        } else {
+            Density::Tall
+        };
+
         // Where clause.
         result.push_str(&self.rewrite_where_clause(where_clause,
                                                    self.config,
                                                    indent,
+                                                   where_density,
                                                    span.hi));
 
         result
@@ -293,6 +307,7 @@ impl<'a> FmtVisitor<'a> {
                     explicit_self: Option<&ast::ExplicitSelf>,
                     one_line_budget: usize,
                     multi_line_budget: usize,
+                    indent: usize,
                     arg_indent: usize,
                     span: Span)
                     -> String {
@@ -341,11 +356,17 @@ impl<'a> FmtVisitor<'a> {
             item.item = arg;
         }
 
+        let indent = match self.config.fn_arg_indent {
+            BlockIndentStyle::Inherit => indent,
+            BlockIndentStyle::Tabbed => indent + self.config.tab_spaces,
+            BlockIndentStyle::Visual => arg_indent,
+        };
+
         let fmt = ListFormatting {
-            tactic: ListTactic::HorizontalVertical,
+            tactic: self.config.fn_args_layout.to_list_tactic(),
             separator: ",",
             trailing_separator: SeparatorTactic::Never,
-            indent: arg_indent,
+            indent: indent,
             h_width: one_line_budget,
             v_width: multi_line_budget,
             ends_with_newline: false,
@@ -424,6 +445,7 @@ impl<'a> FmtVisitor<'a> {
         let body_start = span.lo + BytePos(enum_snippet.find_uncommented("{").unwrap() as u32 + 1);
         let generics_str = self.format_generics(generics,
                                                 " {",
+                                                self.block_indent,
                                                 self.block_indent + self.config.tab_spaces,
                                                 codemap::mk_sp(span.lo,
                                                                body_start));
@@ -565,6 +587,7 @@ impl<'a> FmtVisitor<'a> {
         let generics_str = match generics {
             Some(g) => self.format_generics(g,
                                             opener,
+                                            offset,
                                             offset + header_str.len(),
                                             codemap::mk_sp(span.lo,
                                                            struct_def.fields[0].span.lo)),
@@ -662,14 +685,16 @@ impl<'a> FmtVisitor<'a> {
                        generics: &ast::Generics,
                        opener: &str,
                        offset: usize,
+                       generics_offset: usize,
                        span: Span)
                        -> String {
-        let mut result = self.rewrite_generics(generics, offset, span);
+        let mut result = self.rewrite_generics(generics, offset, generics_offset, span);
 
         if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
             result.push_str(&self.rewrite_where_clause(&generics.where_clause,
                                                        self.config,
                                                        self.block_indent,
+                                                       Density::Tall,
                                                        span.hi));
             result.push_str(&make_indent(self.block_indent));
             result.push('\n');
@@ -714,7 +739,12 @@ impl<'a> FmtVisitor<'a> {
         }
     }
 
-    fn rewrite_generics(&self, generics: &ast::Generics, offset: usize, span: Span) -> String {
+    fn rewrite_generics(&self,
+                        generics: &ast::Generics,
+                        offset: usize,
+                        generics_offset: usize,
+                        span: Span)
+                        -> String {
         // FIXME convert bounds to where clauses where they get too big or if
         // there is a where clause at all.
         let lifetimes: &[_] = &generics.lifetimes;
@@ -723,18 +753,24 @@ impl<'a> FmtVisitor<'a> {
             return String::new();
         }
 
-        let budget = self.config.max_width - offset - 2;
+        let offset = match self.config.generics_indent {
+            BlockIndentStyle::Inherit => offset,
+            BlockIndentStyle::Tabbed => offset + self.config.tab_spaces,
+            // 1 = <
+            BlockIndentStyle::Visual => generics_offset + 1,
+        };
+
+        let h_budget = self.config.max_width - generics_offset - 2;
         // TODO might need to insert a newline if the generics are really long
 
         // Strings for the generics.
-        // 1 = <
         let context = self.get_context();
         // FIXME: don't unwrap
         let lt_strs = lifetimes.iter().map(|lt| {
-            lt.rewrite(&context, budget, offset + 1).unwrap()
+            lt.rewrite(&context, h_budget, offset).unwrap()
         });
         let ty_strs = tys.iter().map(|ty_param| {
-            ty_param.rewrite(&context, budget, offset + 1).unwrap()
+            ty_param.rewrite(&context, h_budget, offset).unwrap()
         });
 
         // Extract comments between generics.
@@ -762,7 +798,7 @@ impl<'a> FmtVisitor<'a> {
             item.item = ty;
         }
 
-        let fmt = ListFormatting::for_fn(budget, offset + 1);
+        let fmt = ListFormatting::for_fn(h_budget, offset);
 
         format!("<{}>", write_list(&items, &fmt))
     }
@@ -771,15 +807,29 @@ impl<'a> FmtVisitor<'a> {
                             where_clause: &ast::WhereClause,
                             config: &Config,
                             indent: usize,
+                            density: Density,
                             span_end: BytePos)
                             -> String {
         if where_clause.predicates.is_empty() {
             return String::new();
         }
 
+        let extra_indent = match self.config.where_indent {
+            BlockIndentStyle::Inherit => 0,
+            BlockIndentStyle::Tabbed | BlockIndentStyle::Visual => config.tab_spaces,
+        };
+
         let context = self.get_context();
-        // 6 = "where ".len()
-        let offset = indent + config.tab_spaces + 6;
+
+        let offset = match self.config.where_pred_indent {
+            BlockIndentStyle::Inherit => indent + extra_indent,
+            BlockIndentStyle::Tabbed => indent + extra_indent + config.tab_spaces,
+            // 6 = "where ".len()
+            BlockIndentStyle::Visual => indent + extra_indent + 6,
+        };
+        // FIXME: if where_pred_indent != Visual, then the budgets below might
+        // be out by a char or two.
+
         let budget = self.config.ideal_width + self.config.leeway - offset;
         let span_start = span_for_where_pred(&where_clause.predicates[0]).lo;
         let items = itemize_list(self.codemap,
@@ -795,7 +845,7 @@ impl<'a> FmtVisitor<'a> {
                                  span_end);
 
         let fmt = ListFormatting {
-            tactic: ListTactic::Vertical,
+            tactic: self.config.where_layout,
             separator: ",",
             trailing_separator: SeparatorTactic::Never,
             indent: offset,
@@ -803,10 +853,17 @@ impl<'a> FmtVisitor<'a> {
             v_width: budget,
             ends_with_newline: true,
         };
+        let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt);
 
-        format!("\n{}where {}",
-                make_indent(indent + config.tab_spaces),
-                write_list(&items.collect::<Vec<_>>(), &fmt))
+        // 9 = " where ".len() + " {".len()
+        if density == Density::Tall || preds_str.contains('\n') ||
+           indent + 9 + preds_str.len() > self.config.max_width {
+            format!("\n{}where {}",
+                    make_indent(indent + extra_indent),
+                    preds_str)
+        } else {
+            format!(" where {}", preds_str)
+        }
     }
 
     fn rewrite_return(&self, ret: &ast::FunctionRetTy) -> String {

src/lists.rs

@@ -28,6 +28,8 @@ pub enum ListTactic {
     Mixed,
 }
 
+impl_enum_decodable!(ListTactic, Vertical, Horizontal, HorizontalVertical, Mixed);
+
 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
 pub enum SeparatorTactic {
     Always,

tests/config/small_tabs.toml

@@ -6,6 +6,13 @@ newline_style = "Unix"
 fn_brace_style = "SameLineWhere"
 fn_return_indent = "WithArgs"
 fn_args_paren_newline = true
+fn_args_layout = "Tall"
+fn_arg_indent = "Visual"
+where_density = "Tall"
+where_indent = "Tabbed"
+where_layout = "Vertical"
+where_pred_indent = "Visual"
+generics_indent = "Visual"
 struct_trailing_comma = "Vertical"
 struct_lit_trailing_comma = "Vertical"
 struct_lit_style = "BlockIndent"

tests/source/fn-custom-2.rs

@@ -0,0 +1,39 @@
+// rustfmt-fn_arg_indent: Inherit
+// rustfmt-generics_indent: Tabbed
+// rustfmt-where_indent: Inherit
+// rustfmt-where_layout: Mixed
+// Test different indents.
+
+fn foo(a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb, TTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>(a: Aaaaaaaaaaaaaaa) {
+    bar();
+}
+
+fn baz() where X: TTTTTTTT {
+    baz();
+}
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+impl Foo {
+    fn foo(self, a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }    
+
+    fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb, TTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>(a: Aaaaaaaaaaaaaaa) {
+        bar();
+    }
+
+    fn baz() where X: TTTTTTTT {
+        baz();
+    }
+}
+
+struct Foo<TTTTTTTTTTTTTTTTTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUUUU, VVVVVVVVVVVVVVVVVVVVVVVVVVV, WWWWWWWWWWWWWWWWWWWWWWWW> {
+    foo: Foo,
+}

tests/source/fn-custom-3.rs

@@ -0,0 +1,34 @@
+// rustfmt-fn_arg_indent: Tabbed
+// rustfmt-generics_indent: Inherit
+// rustfmt-where_layout: HorizontalVertical
+// Test different indents.
+
+fn foo(a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb, TTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>(a: Aaaaaaaaaaaaaaa) {
+    bar();
+}
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+impl Foo {
+    fn foo(self, a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }    
+
+    fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb, TTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>(a: Aaaaaaaaaaaaaaa) {
+        bar();
+    }
+}
+
+struct Foo<TTTTTTTTTTTTTTTTTTTTTTTTTTTT, UUUUUUUUUUUUUUUUUUUUUU, VVVVVVVVVVVVVVVVVVVVVVVVVVV, WWWWWWWWWWWWWWWWWWWWWWWW> {
+    foo: Foo,
+}

tests/source/fn-custom-4.rs

@@ -0,0 +1,15 @@
+// rustfmt-where_pred_indent: Tabbed
+// rustfmt-where_density: Compressed
+// Test different indents.
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+fn qux(a: Aaaaaaaaaaaaaaaaa) where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}

tests/source/fn-custom-5.rs

@@ -0,0 +1,6 @@
+// rustfmt-where_pred_indent: Inherit
+// Test different indents.
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}

tests/source/fn-custom.rs

@@ -0,0 +1,13 @@
+// rustfmt-fn_args_layout: Compressed
+// Test some of the ways function signatures can be customised.
+
+// Test compressed layout of args.
+fn foo(a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+impl Foo {
+    fn foo(self, a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc, d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }    
+}

tests/target/fn-custom-2.rs

@@ -0,0 +1,65 @@
+// rustfmt-fn_arg_indent: Inherit
+// rustfmt-generics_indent: Tabbed
+// rustfmt-where_indent: Inherit
+// rustfmt-where_layout: Mixed
+// Test different indents.
+
+fn foo(a: Aaaaaaaaaaaaaaa,
+b: Bbbbbbbbbbbbbbbb,
+c: Ccccccccccccccccc,
+d: Ddddddddddddddddddddddddd,
+e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb,
+    TTTTTTTTTTTTT,
+    UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>
+    (a: Aaaaaaaaaaaaaaa) {
+    bar();
+}
+
+fn baz()
+where X: TTTTTTTT
+{
+    baz();
+}
+
+fn qux()
+where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+      X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}
+
+impl Foo {
+    fn foo(self,
+    a: Aaaaaaaaaaaaaaa,
+    b: Bbbbbbbbbbbbbbbb,
+    c: Ccccccccccccccccc,
+    d: Ddddddddddddddddddddddddd,
+    e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }
+
+    fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb,
+        TTTTTTTTTTTTT,
+        UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>
+        (a: Aaaaaaaaaaaaaaa) {
+        bar();
+    }
+
+    fn baz()
+    where X: TTTTTTTT
+    {
+        baz();
+    }
+}
+
+struct Foo<TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+    UUUUUUUUUUUUUUUUUUUUUU,
+    VVVVVVVVVVVVVVVVVVVVVVVVVVV,
+    WWWWWWWWWWWWWWWWWWWWWWWW>
+{
+    foo: Foo,
+}

tests/target/fn-custom-3.rs

@@ -0,0 +1,60 @@
+// rustfmt-fn_arg_indent: Tabbed
+// rustfmt-generics_indent: Inherit
+// rustfmt-where_layout: HorizontalVertical
+// Test different indents.
+
+fn foo(a: Aaaaaaaaaaaaaaa,
+    b: Bbbbbbbbbbbbbbbb,
+    c: Ccccccccccccccccc,
+    d: Ddddddddddddddddddddddddd,
+    e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb,
+TTTTTTTTTTTTT,
+UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>
+    (a: Aaaaaaaaaaaaaaa) {
+    bar();
+}
+
+fn qux()
+    where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT, X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}
+
+fn qux()
+    where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+          X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+          X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+          X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}
+
+impl Foo {
+    fn foo(self,
+        a: Aaaaaaaaaaaaaaa,
+        b: Bbbbbbbbbbbbbbbb,
+        c: Ccccccccccccccccc,
+        d: Ddddddddddddddddddddddddd,
+        e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }
+
+    fn bar<'a: 'bbbbbbbbbbbbbbbbbbbbbbbbbbb,
+    TTTTTTTTTTTTT,
+    UUUUUUUUUUUUUUUUUUUU: WWWWWWWWWWWWWWWWWWWWWWWW>
+        (a: Aaaaaaaaaaaaaaa) {
+        bar();
+    }
+}
+
+struct Foo<TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+UUUUUUUUUUUUUUUUUUUUUU,
+VVVVVVVVVVVVVVVVVVVVVVVVVVV,
+WWWWWWWWWWWWWWWWWWWWWWWW>
+{
+    foo: Foo,
+}

tests/target/fn-custom-4.rs

@@ -0,0 +1,23 @@
+// rustfmt-where_pred_indent: Tabbed
+// rustfmt-where_density: Compressed
+// Test different indents.
+
+fn qux()
+    where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+        X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+        X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+        X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}
+
+fn qux() where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT {
+    baz();
+}
+
+fn qux(a: Aaaaaaaaaaaaaaaaa)
+    where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+        X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}

tests/target/fn-custom-5.rs

@@ -0,0 +1,11 @@
+// rustfmt-where_pred_indent: Inherit
+// Test different indents.
+
+fn qux()
+    where X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+    X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+    X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT,
+    X: TTTTTTTTTTTTTTTTTTTTTTTTTTTT
+{
+    baz();
+}

tests/target/fn-custom.rs

@@ -0,0 +1,15 @@
+// rustfmt-fn_args_layout: Compressed
+// Test some of the ways function signatures can be customised.
+
+// Test compressed layout of args.
+fn foo(a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc,
+       d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+    foo();
+}
+
+impl Foo {
+    fn foo(self, a: Aaaaaaaaaaaaaaa, b: Bbbbbbbbbbbbbbbb, c: Ccccccccccccccccc,
+           d: Ddddddddddddddddddddddddd, e: Eeeeeeeeeeeeeeeeeee) {
+        foo();
+    }
+}