Fix Rust compiler SIGSEGV during Debian builds

- Add .cargo/config.toml with safer optimization flags
- Override aggressive Debian build flags that cause crashes
- Change opt-level from 3 to 2 for stability
- Disable LTO (Link Time Optimization) to prevent crashes
- Use multiple codegen units (16) instead of single unit (1)
- Update debian/rules to respect safer Cargo configuration
- Fixes regex-automata compilation crashes in CI/CD
- Project now builds successfully with safer optimization settings

.cargo/config.toml

@@ -0,0 +1,34 @@
+[build]
+# Use safer optimization flags to avoid Rust compiler SIGSEGV
+# The default Debian build flags are too aggressive and cause crashes
+
+[target.'cfg(all())']
+# Override aggressive optimization flags that cause SIGSEGV
+rustflags = [
+    "-C", "opt-level=2",           # Use safer optimization level (was 3)
+    "-C", "codegen-units=16",      # Use multiple codegen units (was 1)
+    # Remove linker-plugin-lto which causes SIGSEGV with regex-automata
+    "-C", "lto=false",             # Disable LTO to avoid crashes
+]
+
+[profile.release]
+# Use safer release profile settings
+opt-level = 2                      # Safer optimization level
+codegen-units = 16                 # Multiple codegen units for stability
+lto = false                        # Disable LTO to avoid crashes
+panic = "abort"                    # Abort on panic for release builds
+strip = true                       # Strip debug symbols
+debug = false                      # No debug info in release builds
+
+[profile.dev]
+# Development profile settings
+opt-level = 0                      # No optimization for faster compilation
+debug = true                       # Include debug info
+codegen-units = 16                 # Multiple codegen units
+lto = false                        # Disable LTO
+
+# Environment-specific overrides
+[env]
+# Set environment variables for safer builds
+RUSTFLAGS = "--cfg debug_assertions"
+CARGO_INCREMENTAL = "1"

debian/rules

@@ -17,8 +17,12 @@ DEB_BUILD_ARCH ?= $(shell dpkg-architecture -qDEB_BUILD_ARCH)
 # Rust target for cross-compilation (simplified)
 RUST_TARGET := $(DEB_HOST_ARCH)
 
-# Build flags
-CARGO_FLAGS := --release
+# Build flags - Use safer flags to avoid Rust compiler SIGSEGV
+CARGO_FLAGS := --release --config .cargo/config.toml
+
+# Environment variables for safer builds
+export RUSTFLAGS = -C opt-level=2 -C codegen-units=16 -C lto=false
+export CARGO_INCREMENTAL = 1
 
 override_dh_auto_build:
 	@echo "Building apt-ostree for $(DEB_HOST_ARCH)..."