feat: custom build folder

ci/run_tests.sh

@@ -366,5 +366,8 @@ pushd both_lib_types
 test $(ls lib/libboth_lib_types* | wc -l) -eq 2
 popd
 
+# Test custom build directory functionality 
+bash "../ci/test_custom_build_dir.sh" "$fpm" hello_world
+
 # Cleanup
 rm -rf ./*/build

ci/test_custom_build_dir.sh

@@ -0,0 +1,98 @@
+#!/usr/bin/env bash
+set -ex
+
+# Test script for custom build directory functionality
+# Usage: ./test_custom_build_dir.sh [fpm_executable] [example_package_dir]
+
+if [ "$1" ]; then
+   fpm="$1"
+else
+   fpm=fpm
+fi
+
+if [ "$2" ]; then
+   test_package="$2"
+else
+   test_package="hello_world"
+fi
+
+echo "Testing custom build directory functionality with package: $test_package"
+
+# Test 1: Custom build directory with CLI option
+pushd "$test_package"
+echo "Test 1: CLI option --build-dir"
+rm -rf ./build custom_build_test
+"$fpm" build --build-dir custom_build_test
+test -d custom_build_test
+test -f custom_build_test/.gitignore
+"$fpm" run --build-dir custom_build_test --target "$test_package"
+# Verify standard build directory was not created
+test ! -d build
+echo "✓ CLI option --build-dir works"
+
+# Test 2: Environment variable
+echo "Test 2: Environment variable FPM_BUILD_DIR"
+rm -rf custom_build_test env_build_test
+FPM_BUILD_DIR=env_build_test "$fpm" build
+test -d env_build_test
+test -f env_build_test/.gitignore
+FPM_BUILD_DIR=env_build_test "$fpm" run --target "$test_package"
+echo "✓ Environment variable FPM_BUILD_DIR works"
+
+# Test 3: CLI option overrides environment variable
+echo "Test 3: CLI option overrides environment variable"
+rm -rf env_build_test cli_override_test
+FPM_BUILD_DIR=env_build_test "$fpm" build --build-dir cli_override_test
+test -d cli_override_test
+test ! -d env_build_test
+echo "✓ CLI option correctly overrides environment variable"
+
+# Test 4: Build directory validation - reserved names
+echo "Test 4: Build directory validation"
+# These should fail with specific error messages
+if "$fpm" build --build-dir src 2>&1 | grep -q "conflicts with source directory"; then
+    echo "✓ Correctly rejected 'src'"
+else
+    echo "ERROR: Should reject 'src'" && exit 1
+fi
+
+if "$fpm" build --build-dir app 2>&1 | grep -q "conflicts with source directory"; then
+    echo "✓ Correctly rejected 'app'"
+else
+    echo "ERROR: Should reject 'app'" && exit 1
+fi
+
+if "$fpm" build --build-dir test 2>&1 | grep -q "conflicts with source directory"; then
+    echo "✓ Correctly rejected 'test'"
+else
+    echo "ERROR: Should reject 'test'" && exit 1
+fi
+
+if "$fpm" build --build-dir . 2>&1 | grep -q "would overwrite the current"; then
+    echo "✓ Correctly rejected '.'"
+else
+    echo "ERROR: Should reject '.'" && exit 1
+fi
+
+# Test 5: Path normalization
+echo "Test 5: Path normalization"
+if "$fpm" build --build-dir ./src 2>&1 | grep -q "conflicts with source directory"; then
+    echo "✓ Correctly rejected './src' (path normalization works)"
+else
+    echo "ERROR: Should reject './src'" && exit 1
+fi
+
+# Test 6: Different commands with custom build directory
+echo "Test 6: Different commands with custom build directory"
+rm -rf test_build_all
+"$fpm" build --build-dir test_build_all
+"$fpm" run --build-dir test_build_all --target "$test_package"
+# Some packages may not have tests, so this might fail but that's expected
+"$fpm" test --build-dir test_build_all 2>/dev/null || echo "No tests in $test_package (expected)"
+echo "✓ All commands work with custom build directory"
+
+# Cleanup test directories
+rm -rf custom_build_test env_build_test cli_override_test test_build_all
+popd
+
+echo "All custom build directory tests passed!"

src/fpm.f90

@@ -69,7 +69,8 @@ subroutine build_model(model, settings, package, error)
     end if
 
     call new_compiler_flags(model,settings)
-    model%build_prefix         = join_path("build", basename(model%compiler%fc))
+    model%build_dir            = settings%build_dir
+    model%build_prefix         = join_path(settings%build_dir, basename(model%compiler%fc))
     model%include_tests        = settings%build_tests
     model%enforce_module_names = package%build%module_naming
     model%module_prefix        = package%build%module_prefix
@@ -79,8 +80,8 @@ subroutine build_model(model, settings, package, error)
     if (allocated(error)) return
 
     ! Create dependencies
-    call new_dependency_tree(model%deps, cache=join_path("build", "cache.toml"), &
-    & path_to_config=settings%path_to_config)
+    call new_dependency_tree(model%deps, cache=join_path(settings%build_dir, "cache.toml"), &
+    & path_to_config=settings%path_to_config, build_dir=settings%build_dir)
 
     ! Build and resolve model dependencies
     call model%deps%add(package, error)
@@ -90,9 +91,9 @@ subroutine build_model(model, settings, package, error)
     call model%deps%update(error)
     if (allocated(error)) return
 
-    ! build/ directory should now exist
-    if (.not.exists("build/.gitignore")) then
-      call filewrite(join_path("build", ".gitignore"),["*"])
+    ! build directory should now exist
+    if (.not.exists(join_path(settings%build_dir, ".gitignore"))) then
+      call filewrite(join_path(settings%build_dir, ".gitignore"),["*"])
     end if
 
     allocate(model%packages(model%deps%ndep))

src/fpm/cmd/export.f90

@@ -44,8 +44,8 @@ subroutine cmd_export(settings)
     if (len_trim(settings%dump_dependencies)>0) then
 
         !> Generate dependency tree
-        filename = join_path("build", "cache.toml")
-        call new_dependency_tree(deps, cache=filename, verbosity=merge(2, 1, settings%verbose))
+        filename = join_path(settings%build_dir, "cache.toml")
+        call new_dependency_tree(deps, cache=filename, verbosity=merge(2, 1, settings%verbose), build_dir=settings%build_dir)
         call deps%add(package, error)
         call handle_error(error)
 

src/fpm/cmd/update.f90

@@ -1,5 +1,5 @@
 module fpm_cmd_update
-  use fpm_command_line, only : fpm_update_settings
+  use fpm_command_line, only : fpm_update_settings, get_fpm_env
   use fpm_dependency, only : dependency_tree_t, new_dependency_tree
   use fpm_error, only : error_t, fpm_stop
   use fpm_filesystem, only : exists, mkdir, join_path, delete_file, filewrite
@@ -20,21 +20,24 @@ subroutine cmd_update(settings)
     type(dependency_tree_t) :: deps
     type(error_t), allocatable :: error
     integer :: ii
-    character(len=:), allocatable :: cache
+    character(len=:), allocatable :: cache, build_dir
 
     call get_package_data(package, "fpm.toml", error, apply_defaults=.true.)
     call handle_error(error)
 
-    if (.not. exists("build")) then
-      call mkdir("build")
-      call filewrite(join_path("build", ".gitignore"),["*"])
+    ! Get build directory from environment variable or use default
+    build_dir = get_fpm_env("BUILD_DIR", "build")
+
+    if (.not. exists(build_dir)) then
+      call mkdir(build_dir)
+      call filewrite(join_path(build_dir, ".gitignore"),["*"])
     end if
 
-    cache = join_path("build", "cache.toml")
+    cache = join_path(build_dir, "cache.toml")
     if (settings%clean) call delete_file(cache)
 
     call new_dependency_tree(deps, cache=cache, verbosity=merge(2, 1, settings%verbose), &
-    & path_to_config=settings%path_to_config)
+    & path_to_config=settings%path_to_config, build_dir=build_dir)
 
     call deps%add(package, error)
     call handle_error(error)

src/fpm/dependency.f90

@@ -205,7 +205,7 @@ module fpm_dependency
 contains
 
   !> Create a new dependency tree
-  subroutine new_dependency_tree(self, verbosity, cache, path_to_config)
+  subroutine new_dependency_tree(self, verbosity, cache, path_to_config, build_dir)
     !> Instance of the dependency tree
     type(dependency_tree_t), intent(out) :: self
     !> Verbosity of printout
@@ -214,9 +214,15 @@ subroutine new_dependency_tree(self, verbosity, cache, path_to_config)
     character(len=*), intent(in), optional :: cache
     !> Path to the global config file.
     character(len=*), intent(in), optional :: path_to_config
+    !> Custom build directory
+    character(len=*), intent(in), optional :: build_dir
 
     call resize(self%dep)
-    self%dep_dir = join_path("build", "dependencies")
+    if (present(build_dir)) then
+        self%dep_dir = join_path(build_dir, "dependencies")
+    else
+        self%dep_dir = join_path("build", "dependencies")
+    end if
 
     if (present(verbosity)) self%verbosity = verbosity
 

src/fpm_backend.F90

@@ -115,7 +115,7 @@ subroutine build_package(targets,model,verbose,dry_run)
     plain_output = .true.
 #endif
 
-    progress = build_progress_t(queue,plain_output)
+    progress = build_progress_t(queue,plain_output,model%build_dir)
 
     ! Loop over parallel schedule regions
     do i=1,size(schedule_ptr)-1

src/fpm_backend_output.f90

@@ -33,6 +33,8 @@ module fpm_backend_output
     logical :: plain_mode = .true.
     !> Store needed when updating previous console lines
     integer, allocatable :: output_lines(:)
+    !> Build directory
+    character(:), allocatable :: build_dir
     !> Queue of scheduled build targets
     type(build_target_ptr), pointer :: target_queue(:)
     !> The compile_commands.json table
@@ -56,11 +58,13 @@ module fpm_backend_output
 contains
 
     !> Initialise a new build progress object
-    function new_build_progress(target_queue,plain_mode) result(progress)
+    function new_build_progress(target_queue,plain_mode,build_dir) result(progress)
         !> The queue of scheduled targets
         type(build_target_ptr), intent(in), target :: target_queue(:)
         !> Enable 'plain' output for progress object
         logical, intent(in), optional :: plain_mode
+        !> Build directory
+        character(*), intent(in), optional :: build_dir
         !> Progress object to initialise
         type(build_progress_t) :: progress
 
@@ -71,6 +75,12 @@ function new_build_progress(target_queue,plain_mode) result(progress)
         progress%plain_mode = plain_mode
         progress%n_complete = 0
 
+        if (present(build_dir)) then
+            progress%build_dir = build_dir
+        else
+            progress%build_dir = "build"
+        end if
+
         allocate(progress%output_lines(progress%n_target))
 
     end function new_build_progress
@@ -191,7 +201,7 @@ subroutine output_write_compile_commands(progress,error)
         type(error_t), allocatable :: error
 
         ! Write compile commands 
-        path = join_path('build','compile_commands.json')
+        path = join_path(progress%build_dir,'compile_commands.json')
 
         call progress%compile_commands%write(filename=path, error=error)