Importing a -shared module's export declare C binding crashes #368

Importing a function that a -shared module binds to a C runtime function with export declare crashes the importing program.

// export_declare_linkname.ts - built with -shared
namespace C {
    @linkname("strlen")          // @dllname("strlen") behaves the same way
    export declare function len(s: string): index;
}

// import_declare_linkname.ts
import './export_declare_linkname'

function main() {
    assert(C.len("hello") == 5);
    print("done.");
}

test-runner -shared import_declare_linkname.ts export_declare_linkname.ts compiles both files, then the program faults when it calls C.len.

Cause

• The importer re-prints the declaration from __decls as @dllimport @dllname("strlen").
• At startup it looks strlen up in the loaded tslang libraries (tslang_search_for_address_of_symbol).
• The exporting DLL never contains strlen: nothing in that module calls it, so the unused declaration is dropped.
• The lookup returns null, and the call jumps through it.

This is older than @linkname: the @dllname spelling crashes the same way on a 2026-09-23 build.

Test

test-compile-shared-export-import-declare-linkname (added in #366) is registered DISABLED until this is fixed. Its static-link twin, test-compile-export-import-declare-linkname, passes.

Possible fixes:

• the importer resolves a declared binding against the process's own symbols, not the tslang library's;
• or the exporting module forwards the symbol.

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