bridge_harfbuzz: no longer require ICU

The motivation for this change is to fix the Windows pkg-config CI,
where MSYS2's switch to the `pkgconf` implementation of `pkg-config` has
surfaced challenges in this crate's build script. But, it is also true
that we only need harfbuzz-icu for versions of Harfbuzz that are very
old at this point, and separating out that dependency will help us work
towards potentially one day being able to swap out the ICU dependency
with something else. So it's good to make that jump for bigger reasons
than just the CI.

Author: pkgw

Cargo.lock

@@ -158,7 +158,7 @@ x86_64-pc-windows-msvc = { triplet = "x64-windows-static-release", install = [
 tectonic_bridge_core = "thiscommit:2023-06-11:PvhF7YB"
 tectonic_bridge_flate = "thiscommit:2021-01-01:eer4ahL4"
 tectonic_bridge_graphite2 = "2c1ffcd702a662c003bd3d7d0ca4d169784cb6ad"
-tectonic_bridge_harfbuzz = "2c1ffcd702a662c003bd3d7d0ca4d169784cb6ad"
+tectonic_bridge_harfbuzz = "thiscommit:2023-09-17:FZwRtUP"
 tectonic_bridge_icu = "thiscommit:2023-09-17:AwTXf3W"
 tectonic_bundles = "thiscommit:2022-03-29:SFnXSaL"
 tectonic_cfg_support = "thiscommit:aeRoo7oa"

Cargo.toml

@@ -1,11 +1,11 @@
-# Copyright 2020-2021 the Tectonic Project
+# Copyright 2020-2023 the Tectonic Project
 # Licensed under the MIT License.
 
 # See README.md for discussion of features (or lack thereof) in this crate.
 
 [package]
 name = "tectonic_bridge_harfbuzz"
-version = "0.0.0-dev.0"  # assigned with cranko (see README)
+version = "0.0.0-dev.0" # assigned with cranko (see README)
 authors = ["Peter Williams <peter@newton.cx>"]
 description = """
 Expose the Harfbuzz C/C++ APIs to Rust/Cargo.
@@ -21,7 +21,6 @@ exclude = ["/harfbuzz/docs/", "/harfbuzz/perf/", "/harfbuzz/test/"]
 
 [dependencies]
 tectonic_bridge_graphite2 = { path = "../bridge_graphite2", version = "0.0.0-dev.0" }
-tectonic_bridge_icu = { path = "../bridge_icu", version = "0.0.0-dev.0" }
 
 [build-dependencies]
 cc = "^1.0.66"
@@ -32,5 +31,4 @@ external-harfbuzz = []
 
 [package.metadata.internal_dep_versions]
 tectonic_bridge_graphite2 = "2722731f9e32c6963fe8c8566a201b33672c5c5a"
-tectonic_bridge_icu = "2c1ffcd702a662c003bd3d7d0ca4d169784cb6ad"
 tectonic_dep_support = "5faf4205bdd3d31101b749fc32857dd746f9e5bc"

crates/bridge_harfbuzz/Cargo.toml

@@ -1,4 +1,4 @@
-// Copyright 2020 the Tectonic Project
+// Copyright 2020-2023 the Tectonic Project
 // Licensed under the MIT License.
 
 //! Harfbuzz build script.
@@ -7,15 +7,23 @@
 mod inner {
     use tectonic_dep_support::{Configuration, Dependency, Spec};
 
-    // TODO: ICU not necessary if Harfbuzz >= 2.5.
     struct HarfbuzzSpec;
 
     impl Spec for HarfbuzzSpec {
+        // We require Harfbuzz >= 1.4, but that version is ancient, and
+        // specifying the version constraint in this string causes problems with
+        // the `pkgconf` implementation of pkg-config on Windows/MSYS2.
+        // (Specifically, its `--modversion` mode won't print anything out when
+        // given two arguments, causing an unhandled crash inside the pkg_config
+        // Rust library.) Likewise, for Harfbuzz < 2.5, the `harfbuzz-icu`
+        // pkg-config item is needed, but this may also cause problems for
+        // pkgconf. If you really need to compile against very old Harfbuzz,
+        // patch this file and don't use pkgconf.
         fn get_pkgconfig_spec(&self) -> &str {
-            "harfbuzz >= 1.4 harfbuzz-icu"
+            "harfbuzz"
         }
 
-        // TODO: can we ensure that the ICU and graphite2 options are enabled?
+        // TODO: can we ensure that the graphite2 option is enabled?
         fn get_vcpkg_spec(&self) -> &[&str] {
             &["harfbuzz"]
         }
@@ -75,26 +83,19 @@ mod inner {
         // Include paths exported by our internal dependencies:
         let graphite2_include_path = env::var("DEP_GRAPHITE2_INCLUDE_PATH").unwrap();
         let graphite2_static = !env::var("DEP_GRAPHITE2_DEFINE_STATIC").unwrap().is_empty();
-        let icu_include_path = env::var("DEP_ICUUC_INCLUDE_PATH").unwrap();
 
         let mut cfg = cc::Build::new();
 
         cfg.cpp(true)
             .flag("-std=c++11")
             .warnings(false)
             .define("HAVE_GRAPHITE2", "1")
-            .define("HAVE_ICU", "1")
-            .file("harfbuzz/src/harfbuzz.cc")
-            .file("harfbuzz/src/hb-icu.cc");
+            .file("harfbuzz/src/harfbuzz.cc");
 
         for item in graphite2_include_path.split(';') {
             cfg.include(item);
         }
 
-        for item in icu_include_path.split(';') {
-            cfg.include(item);
-        }
-
         if graphite2_static {
             cfg.define("GRAPHITE2_STATIC", "1");
         }
@@ -129,10 +130,6 @@ mod inner {
             print!(";{}", item);
         }
 
-        for item in icu_include_path.split(';') {
-            print!(";{}", item);
-        }
-
         println!();
 
         let dest_dir = include_dir.join("harfbuzz");

crates/bridge_harfbuzz/build.rs

@@ -1,4 +1,4 @@
-// Copyright 2020 the Tectonic Project
+// Copyright 2020-2023 the Tectonic Project
 // Licensed under the MIT License.
 
 //! No Rust code. This crate exists to export the Harfbuzz *C/C++* API into the
@@ -9,7 +9,4 @@
 mod linkage {
     #[allow(unused_imports)]
     use tectonic_bridge_graphite2 as clippyrenamehack1;
-
-    #[allow(unused_imports)]
-    use tectonic_bridge_icu as clippyrenamehack2;
 }

crates/bridge_harfbuzz/src/lib.rs

@@ -40,6 +40,7 @@ authorization from the copyright holders.
 #include <harfbuzz/hb.h>
 #include <harfbuzz/hb-graphite2.h>
 #if !HB_VERSION_ATLEAST(2,5,0)
+/* Note: this configuration is no longer actively tested */
 #include <harfbuzz/hb-icu.h>
 #endif
 #include <harfbuzz/hb-ot.h>