Use an auto-patched copy of rustc_codegen_ssa (dubbed pqp_cg_ssa).

Author: eddyb

.github/workflows/ci.yaml

@@ -76,13 +76,18 @@ jobs:
       - name: build example shaders
         if: ${{ matrix.target != 'aarch64-linux-android' }}
         env:
-          OUT_DIR: "target/tmp"
+          PROFILE: release
+          OUT_DIR: "target/release/ci/out"
         run: cargo run -p example-runner-wgpu-builder --release --no-default-features --features "use-installed-tools"
 
-      - name: build example shaders dev
+      - name: build example shaders (dev aka "debug mode")
         if: ${{ matrix.target != 'aarch64-linux-android' && matrix.target != 'x86_64-apple-darwin' }}
         env:
-          OUT_DIR: "target/tmp"
+          # HACK(eddyb) see `[profile.dev]` in `Cargo.toml` for more on why
+          # `-Zshare-generics=off` is useful (and why it had to be moved here).
+          RUSTFLAGS: -Zshare-generics=off
+          PROFILE: debug
+          OUT_DIR: "target/debug/ci/out"
         run: cargo run -p example-runner-wgpu-builder --no-default-features --features "use-installed-tools"
 
       - name: Build WGPU Example for Android

.github/workflows/lint.sh

@@ -87,3 +87,16 @@ function version_test() {
 # FIXME(eddyb) try to get this working for `spirv-builder`, which has a larger
 # dependency graph, with too much imprecision in upstream `Cargo.toml` files.
 version_test crates/spirv-std
+
+# 3. Ensure `rustc_codegen_spirv` still compiles with `rustc_codegen_ssa`.
+
+# HACK(eddyb) see `crates/rustc_codegen_spirv/build.rs` for more on `pqp_cg_ssa`
+# (a patched copy of `rustc_codegen_ssa`).
+echo ::group::rustc_codegen_spirv_disable_pqp_cg_ssa
+cargo clippy \
+    --manifest-path "crates/rustc_codegen_spirv/Cargo.toml" \
+    --no-default-features \
+    --features "$FEAT" \
+    --all-targets \
+    -- -D warnings --cfg rustc_codegen_spirv_disable_pqp_cg_ssa
+echo ::endgroup::

Cargo.lock

@@ -1,3 +1,8 @@
+# HACK(eddyb) meant for `[profile.dev]` `rustflags` overrides below, but sadly
+# not configurable w/o breaking `Cargo.toml` parsing from non-nightly Cargo.
+#
+# cargo-features = ["profile-rustflags"]
+
 [workspace]
 resolver = "2"
 members = [
@@ -60,3 +65,15 @@ codegen-units = 256
 opt-level = 3
 incremental = true
 codegen-units = 256
+
+# HACK(eddyb) reduce the number of linker exports and/or imports, by avoiding
+# inter-CGU linkage, to stay under the 64Ki MSVC limit for `rustc_codegen_spirv`
+# when building it in "debug mode" (only relevant to CI for now, realistically),
+# i.e. working around this issue: https://github.com/rust-lang/rust/issues/53014.
+[profile.dev]
+# HACK(eddyb) fewer inter-crate exports/imports (not just inter-CGU), but sadly
+# not configurable w/o breaking `Cargo.toml` parsing from non-nightly Cargo
+# (moved to `.github/workflows/ci.yaml` as `RUSTFLAGS: -Zshare-generics=off`).
+#
+# rustflags = ["-Zshare-generics=off"]
+codegen-units = 1

Cargo.toml

@@ -39,6 +39,11 @@ num-traits = { workspace = true, default-features = true }
 once_cell = "1"
 regex = { version = "1", features = ["perf"] }
 
+# HACK(eddyb) deps of `rustc_codegen_ssa`, for `pqp_cg_ssa` (see `build.rs`),
+# that cannot be handled with just `extern crate` pulling out of the sysroot.
+object = { version = "0.32.1",  default-features = false, features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write", "wasm"] }
+thorin-dwp = "0.7"
+
 # Normal dependencies.
 ar = "0.9.0"
 either = "1.8.0"
@@ -56,7 +61,10 @@ itertools = "0.10.5"
 [dev-dependencies]
 pipe = "0.4"
 pretty_assertions = "1.0"
-tempfile = "3.4"
+
+# HACK(eddyb) can't re-introduce deps of `rustc_codegen_ssa`, for `pqp_cg_ssa`
+# (see `build.rs`).
+# tempfile = "3.4"
 
 # Note that in order to use RA and have access to `rustc_*` crates, you also
 # need to set `"rust-analyzer.rustcSource": "discover"` in e.g. VSCode.