implement: unit identity -- dotted paths, name rules, source path

Units start here, with the part that needs no import graph: what a unit is
called and where it must live.

The parser only ever read a single identifier after `unit` and `import`, so
`unit game.main;` and `import std.io;` were syntax errors -- which is why the
dotted fixtures failed at the semicolon. It now reads a dotted path and stores
it canonically, dots included, since that spelling is the unit's identity
everywhere else. `import a.b as c;` parses too, with the alias on the node.

resolve.c is the new pass between parsing and checking, for the questions that
span files. It carries SPEC 8.1 so far: each path segment is ASCII lowercase,
starts with a letter, continues with letters, digits or underscore, and is at
most eight characters; and the dotted path must match the source path it was
read from, so game.world.map has to come from game/world/map.fe. The source
side is folded to lowercase before comparing, because a case-insensitive host
must not let two spellings become two units.

That rule then applied to the fixtures, which were not obeying it: 57 declared
a unit name unrelated to their file, left over from the milestone directories,
and eight had names too long to be legal. Both are now aligned -- the rule is
worth having only if the tree follows it.

units: badupper, badlong and unitbad pass. 138 -> 146 of 188. The rest of
units/ needs the import graph, which is the next piece: resolution, cycles,
bindings and visibility.

fec/tests/format/bad_ari.fe

@@ -1,4 +1,4 @@
-unit m4_bad_arity;
+unit bad_ari;
 
 fn main() -> i32 {
     @print("{} {}", 1);

fec/tests/format/bad_bufw.fe

@@ -1,4 +1,4 @@
-unit m4_bad_buffer_writer;
+unit bad_bufw;
 
 fn main() -> void {
     var raw: [4]u8 = [0, 0, 0, 0];

fec/tests/format/bad_cls.fe

@@ -1,4 +1,4 @@
-unit m4_bad_cls;
+unit bad_cls;
 
 fn main() -> i32 {
     @print("}", 1);

fec/tests/format/bad_many.fe

@@ -1,4 +1,4 @@
-unit m4_bad_many;
+unit bad_many;
 
 fn main() -> i32 {
     @print("{}", 1, 2);

fec/tests/format/bad_open.fe

@@ -1,4 +1,4 @@
-unit m4_bad_open;
+unit bad_open;
 
 fn main() -> i32 {
     @print("{", 1);

fec/tests/format/bad_run.fe

@@ -1,4 +1,4 @@
-unit m4_bad_runtime;
+unit bad_run;
 
 fn main() -> i32 {
     var fmt: str = "{}";

fec/tests/format/bad_try.fe

@@ -1,4 +1,4 @@
-unit m4_bad_try;
+unit bad_try;
 
 fn main() -> i32 {
     try @print("nope");

fec/tests/format/bad_type.fe

@@ -1,4 +1,4 @@
-unit m4_bad_type;
+unit bad_type;
 
 struct Point { x: i32, }
 

fec/tests/format/bad_verb.fe

@@ -1,4 +1,4 @@
-unit m4_bad_verb;
+unit bad_verb;
 
 fn main() -> i32 {
     @print("{q}", 1);

fec/tests/format/bad_writ.fe

@@ -1,4 +1,4 @@
-unit m4_bad_writer;
+unit bad_writ;
 
 fn main() -> i32 {
     var x: i32 = 0;

fec/tests/format/ok_forma.fe

@@ -1,4 +1,4 @@
-unit m4_format;
+unit ok_forma;
 
 const FMT: str = "n={} hex={x} c={c} s={s} b={b} {{ok}}\n";
 

fec/tests/format/ok_prop.fe

@@ -1,4 +1,4 @@
-unit m4_prop;
+unit ok_prop;
 
 pub fn propagate(w: io.Writer) -> !void {
     try @fprint(w, "a{}b", 1);

fec/tests/format/ok_try_f.fe

@@ -1,4 +1,4 @@
-unit m4_try_fprint;
+unit ok_try_f;
 
 fn main() -> !void {
     var raw: [4]u8 = [0, 0, 0, 0];

fec/tests/own/bad_clos.fe

@@ -1,4 +1,4 @@
-unit m5_bad_consuming_close;
+unit bad_clos;
 
 struct FileLike {
     handle: i32,

fec/tests/own/bad_cond.fe

@@ -1,4 +1,4 @@
-unit m5_bad_conditional;
+unit bad_cond;
 
 fn take(p: ^i32) -> void { mem.destroy(p); }
 

fec/tests/own/bad_dbl.fe

@@ -1,4 +1,4 @@
-unit m5_bad_double;
+unit bad_dbl;
 
 fn bad(p: ^i32) -> void {
     mem.destroy(p);

fec/tests/own/bad_dest.fe

@@ -1,4 +1,4 @@
-unit m5_bad_destroy;
+unit bad_dest;
 
 fn bad(x: i32) -> void {
     mem.destroy(x);

fec/tests/own/bad_drop.fe

@@ -1,4 +1,4 @@
-unit m5_bad_drop;
+unit bad_drop;
 
 struct Box {
     value: i32,

fec/tests/own/bad_loop.fe

@@ -1,4 +1,4 @@
-unit m5_bad_loop_move;
+unit bad_loop;
 
 fn take(p: ^i32) -> void { mem.destroy(p); }
 

fec/tests/own/bad_move.fe

@@ -1,4 +1,4 @@
-unit m5_bad_move;
+unit bad_move;
 
 fn take(p: ^i32) -> void { mem.destroy(p); }
 

fec/tests/own/bad_proj.fe

@@ -1,4 +1,4 @@
-unit m5_bad_projection_move;
+unit bad_proj;
 
 struct Holder { p: ^i32 }
 fn take(p: ^i32) -> void { mem.destroy(p); }

fec/tests/own/ok_defer.fe

@@ -1,4 +1,4 @@
-unit m5_defer;
+unit ok_defer;
 
 pub fn cleanup(p: ^i32) -> void {
     defer { mem.destroy(p); }

fec/tests/own/ok_owned.fe

@@ -1,4 +1,4 @@
-unit m5_owned;
+unit ok_owned;
 
 fn main() -> !void {
     var p: ^i32 = try mem.create(0);

fec/tests/parse/keybuilt.fe

@@ -1,4 +1,4 @@
-unit keywords_and_builtins;
+unit keybuilt;
 
 pub fn demo() {
     let a = true and not false;

fec/tests/parse/logical.fe

@@ -1,3 +1,3 @@
 // ERROR:logical operator
-unit old_logic;
+unit logical;
 fn main() { let x = true && false; }

fec/tests/parse/misssemi.fe

@@ -1,3 +1,3 @@
 // ERROR:expected ';'
-unit broken;
+unit misssemi;
 fn main() { let x: i32 = 1 }

fec/tests/parse/unclcomm.fe

@@ -1,3 +1,3 @@
 // ERROR:unterminated block comment
-unit broken;
+unit unclcomm;
 /* no ending delimiter

fec/tests/parse/v012form.fe

@@ -1,4 +1,4 @@
-unit v012_forms;
+unit v012form;
 
 shared atomic var ticks: u16 = 0;
 packed struct Packet {

fec/tests/types/bad_ari.fe

@@ -1,4 +1,4 @@
-unit bad_arity;
+unit bad_ari;
 
 fn add(a: i32, b: i32) -> i32 {
     return a + b;

fec/tests/types/bad_asgn.fe

@@ -1,4 +1,4 @@
-unit bad_assign;
+unit bad_asgn;
 
 fn main() -> i32 {
     let value: i32 = 1;

fec/tests/types/bad_cond.fe

@@ -1,4 +1,4 @@
-unit bad_condition;
+unit bad_cond;
 
 fn main() -> i32 {
     if 1 { return 0; }

fec/tests/types/bad_mlet.fe

@@ -1,4 +1,4 @@
-unit m3_bad_mut_let;
+unit bad_mlet;
 
 fn bad() -> void {
     var raw: [2]u8 = [1, 2];

fec/tests/types/bad_ret.fe

@@ -1,4 +1,4 @@
-unit bad_return;
+unit bad_ret;
 
 fn main() -> i32 {
     return true;

fec/tests/types/bad_shwr.fe

@@ -1,4 +1,4 @@
-unit m3_bad_shared_write;
+unit bad_shwr;
 
 fn bad(s: []u8) -> void {
     s[0] = 1;

fec/tests/types/bad_type.fe

@@ -1,4 +1,4 @@
-unit bad_types;
+unit bad_type;
 
 fn add(a: i32, b: i32) -> i32 {
     return a + b;

fec/tests/types/bad_unit.fe

@@ -1,4 +1,4 @@
-unit bad_uninit;
+unit bad_unit;
 
 fn main() -> i32 {
     var value: i32;

fec/tests/types/bad_unk.fe

@@ -1,4 +1,4 @@
-unit bad_unknown;
+unit bad_unk;
 
 fn main() -> i32 {
     return missing_name;

fec/tests/types/badarr.fe

@@ -1,4 +1,4 @@
-unit fail_m3_array;
+unit badarr;
 fn main() -> i32 {
     let a: [2]i32 = [1, true, 3];
     return a[0];

fec/tests/types/badchar.fe

@@ -1,4 +1,4 @@
-unit fail_m3_char;
+unit badchar;
 
 fn main() -> i32 {
     let u: u8 = 'A';

fec/tests/types/badcycle.fe

@@ -1,4 +1,4 @@
-unit fail_m3_cycle;
+unit badcycle;
 
 struct A { b: B, }
 struct B { a: A, }

fec/tests/types/badfield.fe

@@ -1,4 +1,4 @@
-unit fail_m3_let_field;
+unit badfield;
 
 struct Point { x: i32, y: i32, }
 fn main() -> i32 {

fec/tests/types/badfld.fe

@@ -1,4 +1,4 @@
-unit fail_m3_fields;
+unit badfld;
 struct Point { x: i32, y: i32, }
 fn main() -> i32 {
     let p: Point = Point{ x: 1 };

fec/tests/types/badindex.fe

@@ -1,4 +1,4 @@
-unit fail_m3_let_index;
+unit badindex;
 
 fn main() -> i32 {
     let a: [2]i32 = [1, 2];

fec/tests/types/badmat.fe

@@ -1,4 +1,4 @@
-unit fail_m3_match;
+unit badmat;
 enum Shape { Empty, Circle(i32), }
 fn main() -> i32 {
     match Shape.Empty { Empty => 0; }

fec/tests/types/badstr.fe

@@ -1,4 +1,4 @@
-unit fail_m3_str;
+unit badstr;
 fn main() -> i32 {
     var text: str = "abc";
     text[0] = 'z';

fec/tests/types/ok_arra1.fe

@@ -1,4 +1,4 @@
-unit m3_arrayctx;
+unit ok_arra1;
 
 fn main() -> i32 {
     let bytes: [3]u8 = [1, 2, 3];

fec/tests/types/ok_array.fe

@@ -1,4 +1,4 @@
-unit m3_array;
+unit ok_array;
 
 fn main() -> i32 {
     let a: [3]i32 = [1, 2, 3];

fec/tests/types/ok_castw.fe

@@ -1,4 +1,4 @@
-unit cast_while;
+unit ok_castw;
 
 pub fn main() -> i32 {
     var x: i16 = 0;

fec/tests/types/ok_char.fe

@@ -1,4 +1,4 @@
-unit m3_char;
+unit ok_char;
 
 fn main() -> i32 {
     let c: char = '\u0041';

fec/tests/types/ok_enum.fe

@@ -1,4 +1,4 @@
-unit m3_enum;
+unit ok_enum;
 
 enum Shape { Empty, Circle(i32), Rect { w: i32, h: i32, }, }
 

fec/tests/types/ok_for.fe

@@ -1,4 +1,4 @@
-unit m3_for;
+unit ok_for;
 
 fn main() -> i32 {
     var total: i32 = 0;

fec/tests/types/ok_hello.fe

@@ -1,4 +1,4 @@
-unit hello;
+unit ok_hello;
 
 fn add(a: i32, b: i32) -> i32 {
     return a + b;

fec/tests/types/ok_mutab.fe

@@ -1,4 +1,4 @@
-unit m3_mutable;
+unit ok_mutab;
 
 fn takes_shared(s: []u8) -> u8 { return s[0]; }
 

fec/tests/types/ok_neste.fe

@@ -1,4 +1,4 @@
-unit m3_nested;
+unit ok_neste;
 
 struct Outer { inner: Inner, }
 struct Inner { value: i32, }

fec/tests/types/ok_scope.fe

@@ -1,4 +1,4 @@
-unit scopes;
+unit ok_scope;
 
 fn register(switch: i32) -> i32 {
     let auto: i32 = switch;

fec/tests/types/ok_str.fe

@@ -1,4 +1,4 @@
-unit m3_str;
+unit ok_str;
 
 fn main() -> i32 {
     let text: str = "abc";

fec/tests/types/ok_struc.fe

@@ -1,4 +1,4 @@
-unit m3_struct;
+unit ok_struc;
 
 struct Point { x: i32, y: i32, }
 packed struct PackedPoint { x: u8, y: i32, }