M10: the print crate's tests delay-load the print DLLs too (#2630)

The pdfcraft-print unit-test executable imported windows.data.pdf.dll and
prntvpt.dll at load time (the windows crate binds them with raw-dylib), so
on a Windows installation without them it could not start, and the tests
of the missing-DLL guard never ran there. crates/print/build.rs now passes
/DELAYLOAD for both and delayimp.lib on MSVC, as the applications' build
scripts do. Link arguments from a build script reach only this package's
own executables, so dependents are unaffected.

dumpbin /imports: before, both DLLs under "the following imports"; after,
under "the following delay load imports". A copy of each test binary with
prntvpt.dll renamed to a DLL that doesn't exist: the old one exits with
0xC0000135 (STATUS_DLL_NOT_FOUND) before main, the new one starts and runs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq7HyCfwzyRXj4VfQAVVdv

apps/pdfcraft-cli/build.rs

@@ -10,7 +10,7 @@
 /// driver's print capabilities). Trimmed Windows installations (NTLite) can lack them, and a
 /// load-time import of a missing DLL stops the program before `main` (#2630). Delay-loaded, they
 /// load on the first print; `pdfcraft_print::spool` checks they exist before calling in.
-/// Same list in `apps/pdfcraft{,-cli}/build.rs` and `crates/print/src/spool.rs`.
+/// Same list in `apps/pdfcraft{,-cli}/build.rs`, `crates/print/build.rs` and `crates/print/src/spool.rs`.
 const DELAY_LOADED: [&str; 2] = ["windows.data.pdf.dll", "prntvpt.dll"];
 
 fn main() {

apps/pdfcraft/build.rs

@@ -13,7 +13,7 @@ mod windows_manifest;
 /// driver's print capabilities). Trimmed Windows installations (NTLite) can lack them, and a
 /// load-time import of a missing DLL stops the program before `main` (#2630). Delay-loaded, they
 /// load on the first print; `pdfcraft_print::spool` checks they exist before calling in.
-/// Same list in `apps/pdfcraft{,-cli}/build.rs` and `crates/print/src/spool.rs`.
+/// Same list in `apps/pdfcraft{,-cli}/build.rs`, `crates/print/build.rs` and `crates/print/src/spool.rs`.
 const DELAY_LOADED: [&str; 2] = ["windows.data.pdf.dll", "prntvpt.dll"];
 
 fn main() {

crates/print/build.rs

@@ -0,0 +1,23 @@
+//! Windows (MSVC) only: delay-load the print DLLs in this crate's own test executable, as the
+//! applications do (`apps/pdfcraft{,-cli}/build.rs`), so it starts on a Windows installation that
+//! lacks them (#2630) and its tests of the missing-DLL guard in `src/spool.rs` run there. Link
+//! arguments from a build script reach only this package's own executables (its tests), never
+//! the crates that depend on it; each application sets its own.
+//!
+//! On every other target this does nothing.
+
+/// The in-box DLLs only printing uses (Windows.Data.Pdf draws the job, prntvpt reads the
+/// driver's print capabilities). Same list in `apps/pdfcraft{,-cli}/build.rs` and
+/// `src/spool.rs`.
+const DELAY_LOADED: [&str; 2] = ["windows.data.pdf.dll", "prntvpt.dll"];
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    if std::env::var("CARGO_CFG_TARGET_OS").as_deref() != Ok("windows") || std::env::var("CARGO_CFG_TARGET_ENV").as_deref() != Ok("msvc") {
+        return;
+    }
+    for dll in DELAY_LOADED {
+        println!("cargo:rustc-link-arg=/DELAYLOAD:{dll}");
+    }
+    println!("cargo:rustc-link-arg=delayimp.lib");
+}

crates/print/src/spool.rs

@@ -7,9 +7,9 @@ pub use craft_print::{
 };
 
 /// Windows: the in-box DLLs printing draws and describes jobs with. The executables delay-load
-/// them (`apps/pdfcraft{,-cli}/build.rs`, the same list) so a Windows installation without them
-/// still starts (#2630); a call into a missing delay-loaded DLL would end the process, so
-/// printing checks for them first.
+/// them (`apps/pdfcraft{,-cli}/build.rs`, and `build.rs` for this crate's tests: the same list)
+/// so a Windows installation without them still starts (#2630); a call into a missing
+/// delay-loaded DLL would end the process, so printing checks for them first.
 #[cfg(windows)]
 pub(crate) const PRINT_DLLS: [&str; 2] = ["windows.data.pdf.dll", "prntvpt.dll"];