w6c,ww: mangle an imported package's fn main under separate compilation (M4 E3, #99)

The bare-`main` carve-out (which keeps the link entry's main unmangled)
keyed on `leaf == "main" && imported == 0`. Under the combined path a
dependency's body folds in with imported==1, so only the root's main
stayed bare. Under separate compilation each package is its own unit and
a dependency's body carries a path-mangling module-reset but imported==0
(#57) — so an imported `fn main` matched the carve-out, emitted a bare
`TEXT main`, and collided with the root entry (`w6l: duplicate symbol
main`). The combined path was unaffected, so this only surfaced under sep.

Gate the carve-out with sep_isdep = (wwiout != NULL): the producer emits a
.wwi output only for dependency units, never for the root/link-entry unit
(root stripped, #69), symmetric on both stages. Only the root unit's main
now stays bare; an imported package's main mangles on its import path
(e.g. aa.bb.main). Both stages.

Gate: test/wcc/989_depmain_sep.c (table-driven, dotted + single-component
shapes, both stages; asserts the mangled dep main + a single bare root
main + cs==ww byte-id; combined path stays neutral).

selfhost/cmd/w6c/main.combined.ww

@@ -41326,8 +41326,11 @@ fn cgfn(c: *cgen, fn_: *syntax.node) void = {
 	// (undefined `main`). #84's bare-module handling is the orthogonal
 	// axis (a package-LESS `//ww:module-reset` fn, nmod empty), resolved
 	// in modlookupforfn, NOT here.
+	// #99: gate on sepisdep — under sep a dep unit's main is imported==0
+	// (path-carrying `//ww:module-reset`, #57); only the root/link-entry
+	// unit (wwiout==nil, #69) keeps the bare label.
 	emitline("TEXT ");
-	if (syntax.streq(fn_.str, "main") && fn_.imported == 0) {
+	if (syntax.streq(fn_.str, "main") && fn_.imported == 0 && c.sepisdep == 0) {
 		emitbytes(fn_.str.ptr, fn_.str.len: u64);
 	} else {
 		emitfnname(c, fn_.str, fn_.nmod);
@@ -41932,6 +41935,14 @@ type cgen = struct {
 	// must survive to the post-loop emitletdataw/emitdefconstants pass,
 	// like strlits/ffis. Symmetric with cstage Cg.sep_mode.
 	sepmode: i32,
+	// #99: this unit is a sep DEPENDENCY, not the root/link-entry unit.
+	// Set from `wwiout != nil` in main — the producer passes -I (.wwi
+	// output) to DEP units only; the root's .wwi is stripped (#69), so
+	// wwiout==nil <=> root/link-entry unit. Gates the bare-`main` carve-
+	// out: a dep's `fn main` mangles on its path like any decl; only the
+	// root entry stays bare. Like sepmode, NOT reset by cgeninit (per-fn).
+	// Symmetric with cstage Cg.sep_isdep.
+	sepisdep: i32,
 };
 
 // Top-level mutable `let` registry. Mirrors cmd/w6c/cgen.c LetVar.
@@ -45263,7 +45274,12 @@ fn collectmods(c: *cgen, file: *syntax.node) void = {
 				// label). M1 #32: only ROOT main (imported==0) stays bare;
 				// an IMPORTED `fn main` mangles on its path. Mirrors
 				// cstage cgen.c mod_collect.
-				if (!syntax.streq(d.str, "main") || d.imported != 0) {
+				// #99: under sep a dep unit's main is imported==0 too (its
+				// body is composed with a path-carrying `//ww:module-reset`,
+				// #57), so imported==0 no longer means "root unit" per-unit.
+				// sepisdep (wwiout==nil <=> root/link-entry unit, #69)
+				// re-mangles a dep's main; only the root's stays bare.
+				if (!syntax.streq(d.str, "main") || d.imported != 0 || c.sepisdep != 0) {
 					let m: *modent = alloc(modent{mname=d.str, nmod=d.nmod, omod=d.nmod, mnext=c.mods})!;
 					c.mods = m;
 				};
@@ -46339,6 +46355,10 @@ export fn main(argc: i32, argv: **u8) i32 = {
 	let cg: cgen;
 	cgeninit(&cg);
 	cg.sepmode = sepmode;
+	// #99: wwiout != nil <=> this is a sep DEP unit (the producer passes
+	// -I to deps only; the root's .wwi is stripped per #69). Gates the
+	// bare-`main` carve-out so only the root/link-entry main stays bare.
+	if (wwiout != nil) { cg.sepisdep = 1i32; };
 	cgfile(&cg, f);
 	return 0;
 };

selfhost/cmd/w6c/main.ww

@@ -195,6 +195,10 @@ export fn main(argc: i32, argv: **u8) i32 = {
 	let cg: cgen;
 	cgeninit(&cg);
 	cg.sepmode = sepmode;
+	// #99: wwiout != nil <=> this is a sep DEP unit (the producer passes
+	// -I to deps only; the root's .wwi is stripped per #69). Gates the
+	// bare-`main` carve-out so only the root/link-entry main stays bare.
+	if (wwiout != nil) { cg.sepisdep = 1i32; };
 	cgfile(&cg, f);
 	return 0;
 };

selfhost/cmd/wcc/cgen.ww

@@ -544,6 +544,14 @@ type cgen = struct {
 	// must survive to the post-loop emitletdataw/emitdefconstants pass,
 	// like strlits/ffis. Symmetric with cstage Cg.sep_mode.
 	sepmode: i32,
+	// #99: this unit is a sep DEPENDENCY, not the root/link-entry unit.
+	// Set from `wwiout != nil` in main — the producer passes -I (.wwi
+	// output) to DEP units only; the root's .wwi is stripped (#69), so
+	// wwiout==nil <=> root/link-entry unit. Gates the bare-`main` carve-
+	// out: a dep's `fn main` mangles on its path like any decl; only the
+	// root entry stays bare. Like sepmode, NOT reset by cgeninit (per-fn).
+	// Symmetric with cstage Cg.sep_isdep.
+	sepisdep: i32,
 };
 
 // Top-level mutable `let` registry. Mirrors cmd/w6c/cgen.c LetVar.
@@ -3875,7 +3883,12 @@ fn collectmods(c: *cgen, file: *syntax.node) void = {
 				// label). M1 #32: only ROOT main (imported==0) stays bare;
 				// an IMPORTED `fn main` mangles on its path. Mirrors
 				// cstage cgen.c mod_collect.
-				if (!syntax.streq(d.str, "main") || d.imported != 0) {
+				// #99: under sep a dep unit's main is imported==0 too (its
+				// body is composed with a path-carrying `//ww:module-reset`,
+				// #57), so imported==0 no longer means "root unit" per-unit.
+				// sepisdep (wwiout==nil <=> root/link-entry unit, #69)
+				// re-mangles a dep's main; only the root's stays bare.
+				if (!syntax.streq(d.str, "main") || d.imported != 0 || c.sepisdep != 0) {
 					let m: *modent = alloc(modent{mname=d.str, nmod=d.nmod, omod=d.nmod, mnext=c.mods})!;
 					c.mods = m;
 				};

selfhost/cmd/wcc/cgendecl.ww

@@ -607,8 +607,11 @@ fn cgfn(c: *cgen, fn_: *syntax.node) void = {
 	// (undefined `main`). #84's bare-module handling is the orthogonal
 	// axis (a package-LESS `//ww:module-reset` fn, nmod empty), resolved
 	// in modlookupforfn, NOT here.
+	// #99: gate on sepisdep — under sep a dep unit's main is imported==0
+	// (path-carrying `//ww:module-reset`, #57); only the root/link-entry
+	// unit (wwiout==nil, #69) keeps the bare label.
 	emitline("TEXT ");
-	if (syntax.streq(fn_.str, "main") && fn_.imported == 0) {
+	if (syntax.streq(fn_.str, "main") && fn_.imported == 0 && c.sepisdep == 0) {
 		emitbytes(fn_.str.ptr, fn_.str.len: u64);
 	} else {
 		emitfnname(c, fn_.str, fn_.nmod);

selfhost/cmd/wwdump/main.combined.ww

@@ -41326,8 +41326,11 @@ fn cgfn(c: *cgen, fn_: *syntax.node) void = {
 	// (undefined `main`). #84's bare-module handling is the orthogonal
 	// axis (a package-LESS `//ww:module-reset` fn, nmod empty), resolved
 	// in modlookupforfn, NOT here.
+	// #99: gate on sepisdep — under sep a dep unit's main is imported==0
+	// (path-carrying `//ww:module-reset`, #57); only the root/link-entry
+	// unit (wwiout==nil, #69) keeps the bare label.
 	emitline("TEXT ");
-	if (syntax.streq(fn_.str, "main") && fn_.imported == 0) {
+	if (syntax.streq(fn_.str, "main") && fn_.imported == 0 && c.sepisdep == 0) {
 		emitbytes(fn_.str.ptr, fn_.str.len: u64);
 	} else {
 		emitfnname(c, fn_.str, fn_.nmod);
@@ -41932,6 +41935,14 @@ type cgen = struct {
 	// must survive to the post-loop emitletdataw/emitdefconstants pass,
 	// like strlits/ffis. Symmetric with cstage Cg.sep_mode.
 	sepmode: i32,
+	// #99: this unit is a sep DEPENDENCY, not the root/link-entry unit.
+	// Set from `wwiout != nil` in main — the producer passes -I (.wwi
+	// output) to DEP units only; the root's .wwi is stripped (#69), so
+	// wwiout==nil <=> root/link-entry unit. Gates the bare-`main` carve-
+	// out: a dep's `fn main` mangles on its path like any decl; only the
+	// root entry stays bare. Like sepmode, NOT reset by cgeninit (per-fn).
+	// Symmetric with cstage Cg.sep_isdep.
+	sepisdep: i32,
 };
 
 // Top-level mutable `let` registry. Mirrors cmd/w6c/cgen.c LetVar.
@@ -45263,7 +45274,12 @@ fn collectmods(c: *cgen, file: *syntax.node) void = {
 				// label). M1 #32: only ROOT main (imported==0) stays bare;
 				// an IMPORTED `fn main` mangles on its path. Mirrors
 				// cstage cgen.c mod_collect.
-				if (!syntax.streq(d.str, "main") || d.imported != 0) {
+				// #99: under sep a dep unit's main is imported==0 too (its
+				// body is composed with a path-carrying `//ww:module-reset`,
+				// #57), so imported==0 no longer means "root unit" per-unit.
+				// sepisdep (wwiout==nil <=> root/link-entry unit, #69)
+				// re-mangles a dep's main; only the root's stays bare.
+				if (!syntax.streq(d.str, "main") || d.imported != 0 || c.sepisdep != 0) {
 					let m: *modent = alloc(modent{mname=d.str, nmod=d.nmod, omod=d.nmod, mnext=c.mods})!;
 					c.mods = m;
 				};