Restore prove into metal feature (risc0#2195)

With risc0#2092 dropping the `metal` feature and risc0#2179 restoring it as an
no-op feature, this PR restores the `prove` feature into it, with the
goal of maintaining semver compatibility.

.github/workflows/main.yml

@@ -245,6 +245,9 @@ jobs:
         run: cargo test -p risc0-r0vm -F $FEATURE -F disable-dev-mode --no-run
       - name: build risc0-zkvm tests without the prove feature
         run: cargo test -p risc0-zkvm -F $FEATURE --no-run
+      - name: build risc0-zkvm tests with the metal feature
+        if: matrix.os == 'macOS'
+        run: cargo test -p risc0-zkvm -F metal --no-run
       - name: test risc0-r0vm
         run: cargo test -p risc0-r0vm -F $FEATURE -F disable-dev-mode
       - run: cargo test -p cargo-risczero -F experimental

risc0/cargo-risczero/Cargo.toml

@@ -71,5 +71,5 @@ experimental = [
   "dep:zip",
   "risc0-zkvm/prove",
 ]
-metal = []
+metal = ["risc0-zkvm/metal"]
 r0vm = ["dep:risc0-r0vm"]

risc0/circuit/recursion/Cargo.toml

@@ -61,7 +61,7 @@ cuda = [
   "std",
 ]
 default = ["prove", "test"]
-metal = []
+metal = ["prove"]
 prove = [
   "dep:cfg-if",
   "dep:downloader",

risc0/circuit/rv32im/Cargo.toml

@@ -52,7 +52,7 @@ cuda = [
   "std",
 ]
 default = ["prove"]
-metal = []
+metal = ["prove"]
 prove = [
   "dep:bytemuck",
   "dep:cfg-if",

risc0/r0vm/Cargo.toml

@@ -29,4 +29,4 @@ cuda = ["risc0-zkvm/cuda"]
 default = []
 disable-dev-mode = ["risc0-zkvm/disable-dev-mode"]
 dual = ["risc0-zkvm/dual"]
-metal = []
+metal = ["risc0-zkvm/metal"]

risc0/zkp/Cargo.toml

@@ -58,7 +58,7 @@ features = ["prove", "std"]
 circuit_debug = []
 cuda = ["dep:cust", "prove", "risc0-sys/cuda"]
 default = []
-metal = []
+metal = ["prove"]
 metal_prefix_products = []
 prove = [
   "dep:ff",

risc0/zkvm/Cargo.toml

@@ -141,7 +141,7 @@ getrandom = ["risc0-zkvm-platform/getrandom"]
 heap-embedded-alloc = [
   "risc0-zkvm-platform/heap-embedded-alloc"
 ]
-metal = []
+metal = ["prove"]
 prove = [
   "client",
   "dep:addr2line",

risc0/zkvm/src/lib.rs

@@ -176,3 +176,10 @@ pub fn is_dev_mode() -> bool {
 
     cfg!(not(feature = "disable-dev-mode")) && is_env_set
 }
+
+#[cfg(feature = "metal")]
+#[test]
+fn metal_implies_prove() {
+    // we should be able to access prove feature items when metal has been enabled
+    let _prover = get_prover_server(&ProverOpts::default());
+}