Fix printing of strings inside functions

Previously we normalised all whitespace in printed out functions,
which would effect whitespace inside strings.

lib/function.gi

@@ -78,13 +78,21 @@ end);
 
 InstallMethod(String, "for a function, with whitespace reduced", [IsFunction and IsInternalRep],
 function(fun)
-    local  s, stream;
+    local  s, stream,lines, pos, i;
     s := "";
     stream := OutputTextString(s, true);
     PrintTo(stream, fun);
     CloseStream(stream);
-    NormalizeWhitespace(s);
-    return MakeImmutable(s);
+    lines := SplitString(s, "\n");
+    for i in [1..Length(lines)] do
+        Chomp(lines[i]);
+        pos := 1;
+        while pos <= Length(lines[i]) and lines[i][pos] = ' ' do
+            pos := pos + 1;
+        od;
+        lines[i] := lines[i]{[pos..Length(lines[i])]};
+    od;
+    return MakeImmutable(JoinStringsWithSeparator(lines, " "));
 end);
 
 BIND_GLOBAL( "VIEW_STRING_OPERATION",

tst/testinstall/function.tst

@@ -137,6 +137,31 @@ gap> Print({x,y} -> x + y, "\n");
 function ( x, y )
     return x + y;
 end
+gap> String({x,y} -> x + y);
+"function ( x, y ) return x + y; end"
+
+# Test nesting
+gap> Print(function(x) if x then if x then while x do od; fi; fi; end, "\n");
+function ( x )
+    if x then
+        if x then
+            while x do
+                ;
+            od;
+        fi;
+    fi;
+    return;
+end
+gap> String(function(x) if x then if x then while x do od; fi; fi; end);
+"function ( x ) if x then if x then while x do ; od; fi; fi; return; end"
+
+# Check strings in functions
+gap> Print({x} -> "a     b","\n");
+function ( x )
+    return "a     b";
+end
+gap> String({x} -> "a     b");
+"function ( x ) return \"a     b\"; end"
 gap> f := ({x,y} -> x + y);
 function( x, y ) ... end
 gap> f(2,3);