feat: add LLVM backend version reporting and improve help formatting (#246)

Add compile-time LLVM version detection and display in --version output,
plus improve help text readability with aligned columns.

Changes:
- Set LLVM version at build time via cargo:rustc-env:
  - Export WAVE_LLVM_MAJOR=14 in all platform-specific linkers
  - Linux (linux_original), macOS (link_macos), Windows (link_windows)
- Add backend() function to llvm_temporary/lib.rs:
  - Retrieve WAVE_LLVM_MAJOR from compile-time environment
  - Return formatted string "LLVM {version}" or None
- Display backend version in --version output:
  - Call llvm_temporary::backend() from version_wave()
  - Print "backend: LLVM 14" with gray color formatting
  - Fallback to "backend: unknown backend" if unavailable
- Improve help text formatting in print_help():
  - Use consistent column width alignment ({:<18}, {:<22})
  - Add descriptive text for each command and option
  - Group related options (Commands, Optimization, Debug)
  - Expand optimization flag descriptions (-O0..-O3, -Oz, -Ofast)
  - Clarify debug option purposes (tokens, AST, IR, MC, hex)
  - Keep practical usage examples at bottom

Output example:
  wavec 0.1.5-pre-beta (Linux 6.x.x)
    backend: LLVM 14

This provides transparency about the compiler toolchain configuration
and improves CLI user experience with readable help formatting.

Signed-off-by: LunaStev <luna@lunastev.org>

Author: LunaStev

llvm_temporary/build.rs

@@ -27,6 +27,8 @@ fn linux_original() {
     println!("cargo:rustc-link-lib=llvm-14");
     println!("cargo:rustc-link-search=native=/usr/lib/llvm-14/lib");
 
+    println!("cargo:rustc-env=WAVE_LLVM_MAJOR=14");
+
     println!("cargo:rustc-link-lib=stdc++");
     println!("cargo:rustc-link-lib=ffi");
     println!("cargo:rustc-link-lib=z");
@@ -53,6 +55,7 @@ fn try_macos_paths() {
 }
 
 fn link_macos(prefix: PathBuf) {
+    println!("cargo:rustc-env=WAVE_LLVM_MAJOR=14");
     let lib = prefix.join("lib");
 
     println!("cargo:rustc-link-search=native={}", lib.display());
@@ -83,6 +86,7 @@ fn try_windows_paths() {
 }
 
 fn link_windows(prefix: PathBuf) {
+    println!("cargo:rustc-env=WAVE_LLVM_MAJOR=14");
     let lib = prefix.join("lib");
 
     println!("cargo:rustc-link-search=native={}", lib.display());

llvm_temporary/src/lib.rs

@@ -1 +1,6 @@
 pub mod llvm_temporary;
+
+pub fn backend() -> Option<String> {
+    option_env!("WAVE_LLVM_MAJOR")
+        .map(|v| format!("LLVM {}", v))
+}

src/lib.rs

@@ -8,6 +8,7 @@ use colorex::Colorize;
 use crate::version::get_os_pretty_name;
 
 use commands::DebugFlags;
+use llvm_temporary::backend;
 
 pub unsafe fn compile_and_run(path: &Path, opt_flag: &str, debug: &DebugFlags) {
     runner::run_wave_file(path, opt_flag, debug);
@@ -26,4 +27,10 @@ pub fn version_wave() {
         version::version().color("2,161,47"),
         os
     );
+
+    if let Some(backend) = backend() {
+        println!("  backend: {}", backend.color("117,117,117"));
+    } else {
+        println!("{}", "  backend: unknown backend".color("117,117,117"));
+    }
 }

src/main.rs

@@ -85,29 +85,84 @@ fn print_usage() {
 }
 
 fn print_help() {
-    println!("{}", "Wave Compiler — Commands & Options".color("145,161,2"));
+    println!("{}", "Wave Compiler".color("145,161,2"));
+    println!("{}", "Commands & Options");
     print_usage();
 
     println!("\nCommands:");
-    println!("  {}      {}", "run <file>".color("38,139,235"), "Execute Wave file");
-    println!("  {}    {}", "build <file>".color("38,139,235"), "Compile Wave file");
-    println!("  {}           {}", "--help".color("38,139,235"), "Show help");
-    println!("  {}       {}", "--version".color("38,139,235"), "Show version");
+    println!(
+        "  {:<18} {}",
+        "run <file>".color("38,139,235"),
+        "Execute Wave file"
+    );
+    println!(
+        "  {:<18} {}",
+        "build <file>".color("38,139,235"),
+        "Compile Wave file"
+    );
+    println!(
+        "  {:<18} {}",
+        "--help".color("38,139,235"),
+        "Show this help message"
+    );
+    println!(
+        "  {:<18} {}",
+        "--version".color("38,139,235"),
+        "Show compiler version"
+    );
 
     println!("\nOptimization:");
-    println!("  -O0, -O1, -O2, -O3, -Oz, -Ofast");
+    println!(
+        "  {:<18} {}",
+        "-O0 .. -O3".color("38,139,235"),
+        "Set optimization level"
+    );
+    println!(
+        "  {:<18} {}",
+        "-Oz".color("38,139,235"),
+        "Optimize for binary size"
+    );
+    println!(
+        "  {:<18} {}",
+        "-Ofast".color("38,139,235"),
+        "Enable aggressive optimizations"
+    );
 
     println!("\nDebug options:");
-    println!("  --debug-wave=tokens");
-    println!("  --debug-wave=ast");
-    println!("  --debug-wave=ir");
-    println!("  --debug-wave=mc");
-    println!("  --debug-wave=hex");
-    println!("  --debug-wave=all");
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=tokens".color("38,139,235"),
+        "Print lexer tokens"
+    );
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=ast".color("38,139,235"),
+        "Print AST"
+    );
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=ir".color("38,139,235"),
+        "Print LLVM IR"
+    );
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=mc".color("38,139,235"),
+        "Print machine code"
+    );
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=hex".color("38,139,235"),
+        "Print raw hex output"
+    );
+    println!(
+        "  {:<22} {}",
+        "--debug-wave=all".color("38,139,235"),
+        "Enable all debug outputs"
+    );
 
     println!("\nExamples:");
     println!("  wavec run test.wave");
     println!("  wavec run -O3 test.wave");
     println!("  wavec run --debug-wave=ir test.wave");
     println!("  wavec run -Ofast --debug-wave=all test.wave");
-}
+}