Fix @attr+do/body concatenation and expand issue0601 tests

Handle `do` and `body` after @-attribute identifiers (e.g. `@safe do`,
`@nogc body`) by routing them through formatKeyword().

`do` is a keyword so any `identifier do` must be a contract.
`body` is an identifier that can also be a variable name, so it needs
the additional guard peekIs(tok!"{") to distinguish contract `body`
from variable declarations like `@custom body = 3;`.

Also add regression tests for `@custom body = 3;` and
`SomeStruct body = foo();`.

Author: dejlek

src/dfmt/formatter.d

@@ -305,7 +305,9 @@ private:
             else
                 formatBlockHeader();
         }
-        else if ((current.text == "body" || current == tok!"do") && peekBackIsFunctionDeclarationEnding())
+        else if ((current.text == "body" || current == tok!"do") && peekBackIsFunctionDeclarationEnding()
+                || current == tok!"do" && peekBackIs(tok!"identifier")
+                || current.text == "body" && peekBackIs(tok!"identifier") && peekIs(tok!"{"))
         {
             formatKeyword();
         }

tests/allman/issue0601.d.ref

@@ -11,4 +11,40 @@ struct S
     void h() @nogc @trusted return
     {
     }
+
+    void i() @system return
+    {
+    }
+
+    void j() pure @safe return
+    {
+    }
+
+    void k() @nogc return
+    {
+    }
+
+    void l() @trusted
+    do
+    {
+    }
+
+    void m() @safe
+    do
+    {
+    }
+
+    void n() @nogc @system
+    do
+    {
+    }
+
+    void o() pure @safe
+    do
+    {
+    }
+
+    // Regression: 'body' as variable name must not be treated as contract keyword
+    @custom body = 3;
+    SomeStruct body = foo();
 }

tests/issue0601.d

@@ -11,4 +11,36 @@ struct S
     void h() @nogc @trusted return
     {
     }
+
+    void i() @system return
+    {
+    }
+
+    void j() pure @safe return
+    {
+    }
+
+    void k() @nogc return
+    {
+    }
+
+    void l() @trusted do
+    {
+    }
+
+    void m() @safe do
+    {
+    }
+
+    void n() @nogc @system do
+    {
+    }
+
+    void o() pure @safe do
+    {
+    }
+
+    // Regression: 'body' as variable name must not be treated as contract keyword
+    @custom body = 3;
+    SomeStruct body = foo();
 }

tests/knr/issue0601.d.ref

@@ -10,4 +10,36 @@ struct S {
     void h() @nogc @trusted return
     {
     }
+
+    void i() @system return
+    {
+    }
+
+    void j() pure @safe return
+    {
+    }
+
+    void k() @nogc return
+    {
+    }
+
+    void l() @trusted
+    do {
+    }
+
+    void m() @safe
+    do {
+    }
+
+    void n() @nogc @system
+    do {
+    }
+
+    void o() pure @safe
+    do {
+    }
+
+    // Regression: 'body' as variable name must not be treated as contract keyword
+    @custom body = 3;
+    SomeStruct body = foo();
 }

tests/otbs/issue0601.d.ref

@@ -7,4 +7,33 @@ struct S {
 
     void h() @nogc @trusted return {
     }
+
+    void i() @system return {
+    }
+
+    void j() pure @safe return {
+    }
+
+    void k() @nogc return {
+    }
+
+    void l() @trusted
+    do {
+    }
+
+    void m() @safe
+    do {
+    }
+
+    void n() @nogc @system
+    do {
+    }
+
+    void o() pure @safe
+    do {
+    }
+
+    // Regression: 'body' as variable name must not be treated as contract keyword
+    @custom body = 3;
+    SomeStruct body = foo();
 }