The driver handled one file. It now loads the graph rooted at the entry file
and checks every unit in it.
The import root is derived rather than configured: a unit named `a.b` read
from `<root>/a/b.fe` fixes `<root>`, so a sibling `import c.d;` is looked for
at `<root>/c/d.fe`. That is enough for the fixtures and for any tree that
follows 8.1, and it means there is no path flag to get wrong yet.
Loading is depth-first with the chain of units currently open kept on a stack,
so meeting one again is a cycle rather than a revisit -- a unit reached twice
by different paths is loaded once. Cycles, imports with no source file, and two
imports claiming the same binding are all reported.
One thing this exposed: FeDiags held a single source buffer, so once a build
spanned several files every excerpt was drawn from whichever file was parsed
last. `cycle/b.fe:3` printed the text of a.fe. fe_diags_source switches it, and
loading and checking both set it per unit.
The cycle fixtures lost their line markers on purpose. Which import closes the
cycle depends on which file you enter from -- entering at a.fe reports b.fe,
entering at b.fe reports a.fe -- so pinning a line would pin an arbitrary half
of a symmetric pair. The message is pinned; the line is not.
units: missing, bindconf and cycle pass, on top of the identity cases.
146 -> 148 of 188. What is left in units/ needs cross-unit name resolution and
visibility: an importer still cannot see `util.answer`.
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.
coolguy