llvm-activate

#!/bin/bash
# llvm-activate: Activates a specific LLVM version for the current session.
# Usage:
#   source llvm-activate             -> Lists available versions
#   source llvm-activate <version>   -> Activates the specified version

# Check if script is being sourced
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    echo "Error: This script must be sourced, not executed directly."
    echo "Usage: source llvm-activate [version]"
    exit 1
fi

# Define the toolchains directory
TOOLCHAINS_DIR="$HOME/.llvm/toolchains"

# If no version is specified, list installed versions
if [ $# -eq 0 ]; then
    echo "Installed versions in $TOOLCHAINS_DIR:"
    if [ -d "$TOOLCHAINS_DIR" ]; then
        for version in "$TOOLCHAINS_DIR"/*; do
            if [ -d "$version" ]; then
                echo "  - $(basename "$version")"
            fi
        done
    else
        echo "No versions installed in $TOOLCHAINS_DIR."
    fi
    return 0
fi

VERSION="$1"
LLVM_DIR="$TOOLCHAINS_DIR/$VERSION"

# Check if the version is installed
if [ ! -d "$LLVM_DIR" ]; then
    echo "Error: Version '$VERSION' is not installed in $TOOLCHAINS_DIR."
    return 1
fi

# Check if another version is already active
if [ -n "$_ACTIVE_LLVM" ]; then
    echo "Error: Another version is already active: $_ACTIVE_LLVM."
    echo "To change, run 'source llvm-deactivate' first."
    return 1
fi

# Backup environment variables if not already backed up
if [ -z "$_OLD_PATH" ]; then
    export _OLD_PATH="$PATH"
    export _OLD_CC="$CC"
    export _OLD_CXX="$CXX"
    export _OLD_LD="$LD"
    export _OLD_PS1="$PS1"
fi

# Update PATH to include the selected LLVM's bin directory
export PATH="$LLVM_DIR/bin:$PATH"

# Update compiler variables (CC and CXX)
export CC="$LLVM_DIR/bin/clang"
export CXX="$LLVM_DIR/bin/clang++"

# Update LD if lld exists
if [ -x "$LLVM_DIR/bin/lld" ]; then
    export LD="$LLVM_DIR/bin/lld"
fi

# Modify the prompt to indicate active LLVM version
export PS1="(LLVM: $VERSION) $_OLD_PS1"

# Set internal variable to indicate active version
export _ACTIVE_LLVM="$VERSION"
export _ACTIVE_LLVM_PATH="$LLVM_DIR"

log_info "LLVM version '$VERSION' activated for this session."
log_info "CC, CXX, and LD have been set; PATH and PS1 have been updated."
log_info "To deactivate, run 'source llvm-deactivate'."