Remove install_source_configs — Tupfile-driven config

docs/reference.md

@@ -259,11 +259,10 @@ putup              # Pass 2: Build with generated configs
 
 **How it works:**
 1. Installs root config if `--config` is specified
-2. Copies subdir `tup.config` files from config root to build tree (out-of-tree only)
-3. Parses all Tupfiles using root `tup.config` only
-4. Identifies rules where any output ends with `tup.config`
-5. Executes only those rules (plus their dependencies)
-6. Does not write to `.pup/index` (avoids conflict with subsequent build)
+2. Parses all Tupfiles using root `tup.config` only
+3. Identifies rules where any output ends with `tup.config`
+4. Executes only those rules (plus their dependencies)
+5. Does not write to `.pup/index` (avoids conflict with subsequent build)
 
 **Relevant Options:**
 - `-v` - Verbose output
@@ -278,7 +277,7 @@ putup              # Pass 2: Build with generated configs
 
 **Using --config for pre-made configs:**
 
-The `--config` option copies an existing config file to the output directory as the root `tup.config`. It then continues with steps 2–6 above: copying subdir configs and running any config-generating rules. Useful for:
+The `--config` option copies an existing config file to the output directory as the root `tup.config`. It then continues with steps 2–5 above, running any config-generating rules. Useful for:
 - Cross-compilation with pre-made toolchain configs
 - CI/CD where configs are externally managed
 - Mixed workflows with a static root config + auto-generated subdir configs
@@ -288,26 +287,25 @@ putup configure -B build --config configs/arm-cross.config
 putup configure -B build-debug -c debug.config
 ```
 
-**Subdir tup.config copying (step 2):**
+**Subdir config installation:**
 
-For out-of-tree builds (`config_root != output_root`), configure automatically copies any `tup.config` files found in subdirectories of the config root to the corresponding locations in the build tree. The root-level `tup.config` is excluded (handled by `--config` or config-generating rules).
+Subdirectory configs are installed via Tupfile copy rules — putup has no built-in config copying. Each subdirectory that needs a scoped `tup.config` ships a `defaults.config` alongside its Tupfile with a copy rule:
 
-This enables per-component scoped configs: each subdirectory ships a `tup.config` alongside its Tupfile. At configure time, these are installed into the build tree where scoped config merging (§6.1) picks them up during the build.
+```tup
+: defaults.config |> cp %f %o |> tup.config
+```
+
+At configure time, these rules are discovered and executed like any other config-generating rule. The resulting `tup.config` files are placed in the build tree where scoped config merging (§6.1) picks them up during the build.
 
 ```bash
-# Config root has per-component configs:
-#   gmp/tup.config, mpfr/tup.config, mpc/tup.config
-#
-# configure installs root config AND copies subdir configs:
+# Each subdir Tupfile has a copy rule for its defaults.config:
 putup configure --config configs/toolchain.config -C . -S ../src -B ../build
 #   → ../build/tup.config          (from --config)
-#   → ../build/gmp/tup.config      (copied from gmp/tup.config)
-#   → ../build/mpfr/tup.config     (copied from mpfr/tup.config)
-#   → ../build/mpc/tup.config      (copied from mpc/tup.config)
+#   → ../build/gmp/tup.config      (from gmp/Tupfile copy rule)
+#   → ../build/mpfr/tup.config     (from mpfr/Tupfile copy rule)
+#   → ../build/mpc/tup.config      (from mpc/Tupfile copy rule)
 ```
 
-For in-tree builds (`config_root == output_root`), step 2 is a no-op — the configs are already in place.
-
 **Important:** You must run `putup configure` before `putup build`. If you skip the configure step, `putup build` will error:
 
 ```
@@ -1648,7 +1646,7 @@ S = ../..  GMP_DIR = gmp  → $(S)/$(GMP_DIR) = ../../gmp  ✓
 S = ..     GMP_DIR = ../gmp → $(S)/$(GMP_DIR) = ../../gmp  ✓
 ```
 
-**Scoped `tup.config` defaults:** Components can also ship default config values in their own `tup.config` — parent configs override child configs on collision (see §6.1 *Scoped Config Merging*).
+**Scoped `tup.config` defaults:** Components ship default config values in a `defaults.config` file with a Tupfile copy rule (`cp %f %o`) that installs it as `tup.config` during configure. Parent configs override child configs on collision (see §6.1 *Scoped Config Merging*).
 
 See `examples/bsp/gcc/` for a complete working example with three interdependent libraries.
 

examples/bsp/Makefile.pup

@@ -40,38 +40,38 @@ configure: resolve-mpn setup-host-configs
 
 # Copy host-specific library configs when building for non-Linux hosts.
 # Linux configs are the in-tree defaults; other hosts overlay from configs/host-$(HOST)/.
-# To restore Linux defaults: git checkout -- gcc/*/tup.config binutils/tup.config
+# To restore Linux defaults: git checkout -- gcc/*/defaults.config binutils/defaults.config
 setup-host-configs:
 	@if [ "$(HOST)" != "linux" ] && [ -d configs/host-$(HOST) ]; then \
 		for cfg in configs/host-$(HOST)/*.config; do \
 			lib=$$(basename "$$cfg" .config); \
-			if [ -f "$$lib/tup.config" ]; then \
-				echo "  COPY $$lib/tup.config (host-$(HOST))"; \
-				cp "$$cfg" "$$lib/tup.config"; \
-			elif [ -f "gcc/$$lib/tup.config" ]; then \
-				echo "  COPY gcc/$$lib/tup.config (host-$(HOST))"; \
-				cp "$$cfg" "gcc/$$lib/tup.config"; \
+			if [ -f "$$lib/defaults.config" ]; then \
+				echo "  COPY $$lib/defaults.config (host-$(HOST))"; \
+				cp "$$cfg" "$$lib/defaults.config"; \
+			elif [ -f "gcc/$$lib/defaults.config" ]; then \
+				echo "  COPY gcc/$$lib/defaults.config (host-$(HOST))"; \
+				cp "$$cfg" "gcc/$$lib/defaults.config"; \
 			fi; \
 		done; \
 	fi
 
 # Resolve mpn sources for the selected CPU target.
-# - gcc/gmp/mpn/tup.config: source lists and per-function toggles (child scope)
-# - gcc/gmp/tup.config: GMP_MPARAM and ASM_ENABLED (parent scope, visible to gmp/Tupfile)
+# - gcc/gmp/mpn/defaults.config: source lists and per-function toggles (child scope)
+# - gcc/gmp/defaults.config: GMP_MPARAM and ASM_ENABLED (parent scope, visible to gmp/Tupfile)
 resolve-mpn:
-	@scripts/resolve-mpn.sh $(MPN_CPU) $(SRCDIR)/gcc/gmp/mpn > gcc/gmp/mpn/tup.config
-	@grep -v '^CONFIG_GMP_MPARAM=\|^CONFIG_ASM_ENABLED=\|^CONFIG_NO_ASM=' gcc/gmp/tup.config > gcc/gmp/tup.config.tmp && mv gcc/gmp/tup.config.tmp gcc/gmp/tup.config
+	@scripts/resolve-mpn.sh $(MPN_CPU) $(SRCDIR)/gcc/gmp/mpn > gcc/gmp/mpn/defaults.config
+	@grep -v '^CONFIG_GMP_MPARAM=\|^CONFIG_ASM_ENABLED=\|^CONFIG_NO_ASM=' gcc/gmp/defaults.config > gcc/gmp/defaults.config.tmp && mv gcc/gmp/defaults.config.tmp gcc/gmp/defaults.config
 	@if [ "$(MPN_CPU)" != "generic" ]; then \
 		arch=$${MPN_CPU%%/*}; \
 		if [ -f "$(SRCDIR)/gcc/gmp/mpn/$$arch/gmp-mparam.h" ]; then \
-			echo "CONFIG_GMP_MPARAM=mpn/$$arch/gmp-mparam.h" >> gcc/gmp/tup.config; \
+			echo "CONFIG_GMP_MPARAM=mpn/$$arch/gmp-mparam.h" >> gcc/gmp/defaults.config; \
 		else \
-			echo "CONFIG_GMP_MPARAM=mpn/generic/gmp-mparam.h" >> gcc/gmp/tup.config; \
+			echo "CONFIG_GMP_MPARAM=mpn/generic/gmp-mparam.h" >> gcc/gmp/defaults.config; \
 		fi; \
-		echo "CONFIG_ASM_ENABLED=y" >> gcc/gmp/tup.config; \
+		echo "CONFIG_ASM_ENABLED=y" >> gcc/gmp/defaults.config; \
 	else \
-		echo "CONFIG_GMP_MPARAM=mpn/generic/gmp-mparam.h" >> gcc/gmp/tup.config; \
-		echo "CONFIG_NO_ASM=1" >> gcc/gmp/tup.config; \
+		echo "CONFIG_GMP_MPARAM=mpn/generic/gmp-mparam.h" >> gcc/gmp/defaults.config; \
+		echo "CONFIG_NO_ASM=1" >> gcc/gmp/defaults.config; \
 	fi
 
 # Multi-variant: build for multiple platforms in parallel

examples/bsp/binutils/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # binutils — cross-assembler (as) + cross-archiver (ar)

examples/bsp/gcc/gcc/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # GCC 15.2.0 — C compiler backend

examples/bsp/gcc/gmp/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # GMP 6.2.1

examples/bsp/gcc/gmp/mpn/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # MPN — low-level multiprecision arithmetic
 #

examples/bsp/gcc/libbacktrace/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # libbacktrace - stack trace support (GCC 15.2.0)

examples/bsp/gcc/libcody/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # libcody - C++ modules protocol library

examples/bsp/gcc/libcpp/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # libcpp - C preprocessor library (GCC 15.2.0)

examples/bsp/gcc/libdecnumber/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # libdecnumber - BID decimal floating-point (GCC 15.2.0)

examples/bsp/gcc/libiberty/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # ============================================================
 # libiberty - GCC utility library

examples/bsp/gcc/mpc/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # MPC 1.2.1 - generated files
 

examples/bsp/gcc/mpfr/Tupfile

@@ -1,4 +1,5 @@
 include_rules
+: defaults.config |> ^ INSTALL %o^ cp %f %o |> tup.config
 
 # MPFR 4.1.0 - generated files
 

include/pup/cli/context.hpp

@@ -6,7 +6,6 @@
 #include "options.hpp"
 #include "pup/core/result.hpp"
 #include "pup/parser/ast.hpp"
-#include "pup/parser/ignore.hpp"
 
 #include <cstdint>
 #include <filesystem>
@@ -127,10 +126,6 @@ auto compute_build_scopes(
 [[nodiscard]]
 auto make_layout_options(Options const& opts) -> LayoutOptions;
 
-/// Load .pupignore patterns (with built-in defaults)
-[[nodiscard]]
-auto load_ignore_list(ProjectLayout const& layout, bool verbose) -> parser::IgnoreList;
-
 /// Context for clean commands
 struct CleanContext {
     std::filesystem::path root;

include/pup/exec/scheduler.hpp

@@ -67,6 +67,7 @@ struct SchedulerOptions {
     bool dry_run = false;                             ///< Print commands without executing
     bool verbose = false;                             ///< Print commands as they run
     std::filesystem::path source_root = {};           ///< Source tree root (where Tupfile.ini lives)
+    std::filesystem::path config_root = {};           ///< Config tree root (where Tupfiles live, for 3-tree builds)
     std::filesystem::path output_root = {};           ///< Output tree root (where outputs/.pup go)
     std::optional<std::chrono::seconds> timeout = {}; ///< Per-command timeout
 };

include/pup/graph/dag.hpp

@@ -390,12 +390,15 @@ auto expand_instruction(Graph const& graph, NodeId cmd_id, PathCache& cache) ->
 /// Expand instruction with canonical path resolution for symlinked source trees.
 /// When source_root is provided, build-tree paths are computed relative to the
 /// canonical (physical) CWD instead of the logical CWD.
+/// In 3-tree builds, config_root locates overlay files (like defaults.config)
+/// that live alongside Tupfiles rather than in source_root.
 [[nodiscard]]
 auto expand_instruction(
     Graph const& graph,
     NodeId cmd_id,
     PathCache& cache,
-    std::filesystem::path const& source_root
+    std::filesystem::path const& source_root,
+    std::filesystem::path const& config_root = {}
 ) -> std::string;
 
 /// Expand instruction pattern (convenience overload, creates temporary cache)

src/cli/cmd_build.cpp

@@ -1088,6 +1088,7 @@ auto build_single_variant(
         .dry_run = opts.dry_run,
         .verbose = opts.verbose,
         .source_root = ctx.layout().source_root,
+        .config_root = ctx.layout().config_root,
         .output_root = ctx.layout().output_root,
     };
 

src/cli/cmd_configure.cpp

@@ -9,7 +9,6 @@
 #include "pup/core/path_utils.hpp"
 #include "pup/exec/scheduler.hpp"
 #include "pup/graph/dag.hpp"
-#include "pup/parser/ignore.hpp"
 
 #include <cstdio>
 #include <cstdlib>
@@ -44,73 +43,11 @@ auto install_config_file(
     return EXIT_SUCCESS;
 }
 
-auto install_source_configs(
-    ProjectLayout const& layout,
-    std::string_view variant_name,
-    bool verbose,
-    pup::parser::IgnoreList const& ignore
-) -> void
-{
-    if (layout.config_root == layout.output_root) {
-        return;
-    }
-
-    auto config_canonical = std::filesystem::weakly_canonical(layout.config_root);
-    auto output_canonical = std::filesystem::weakly_canonical(layout.output_root);
-    auto count = 0;
-    auto ec = std::error_code {};
-
-    for (auto it = std::filesystem::recursive_directory_iterator(config_canonical, ec);
-         it != std::filesystem::recursive_directory_iterator();
-         it.increment(ec)) {
-        if (ec) {
-            fprintf(stderr, "[%.*s] Warning: error scanning configs: %s\n", static_cast<int>(variant_name.size()), variant_name.data(), ec.message().c_str());
-            break;
-        }
-
-        // Skip the output tree if it lives inside config_root (e.g., -B build)
-        if (it->is_directory() && it->path() == output_canonical) {
-            it.disable_recursion_pending();
-            continue;
-        }
-
-        // Skip directories matched by .pupignore
-        if (it->is_directory()) {
-            auto rel = std::filesystem::relative(it->path(), config_canonical);
-            if (ignore.is_ignored(rel)) {
-                it.disable_recursion_pending();
-                continue;
-            }
-        }
-
-        if (!it->is_regular_file() || it->path().filename() != "tup.config") {
-            continue;
-        }
-
-        auto rel = std::filesystem::relative(it->path(), config_canonical);
-        if (rel == "tup.config") {
-            continue;
-        }
-
-        auto dest = layout.output_root / rel;
-        std::filesystem::create_directories(dest.parent_path());
-        std::filesystem::copy_file(it->path(), dest, std::filesystem::copy_options::overwrite_existing);
-        if (verbose) {
-            printf("[%.*s] Copied %s -> %s\n", static_cast<int>(variant_name.size()), variant_name.data(), it->path().string().c_str(), dest.string().c_str());
-        }
-        ++count;
-    }
-    if (count > 0) {
-        printf("[%.*s] Installed %d source config(s)\n", static_cast<int>(variant_name.size()), variant_name.data(), count);
-    }
-}
-
 auto configure_single_variant(
     Options const& opts,
     std::string_view variant_name
 ) -> int
 {
-    // Discover layout once for steps 1 & 2
     auto layout = discover_layout(make_layout_options(opts));
     if (!layout) {
         fprintf(stderr, "[%.*s] Error: %s\n", static_cast<int>(variant_name.size()), variant_name.data(), layout.error().message.c_str());
@@ -125,11 +62,7 @@ auto configure_single_variant(
         }
     }
 
-    // Step 2: Copy source subdir tup.config files to build tree
-    auto ignore = load_ignore_list(*layout, opts.verbose);
-    install_source_configs(*layout, variant_name, opts.verbose, ignore);
-
-    // Step 3: Run config-generating rules
+    // Step 2: Run config-generating rules
     auto scopes = compute_build_scopes(opts, *layout);
     auto ctx_opts = BuildContextOptions {
         .verbose = opts.verbose,
@@ -200,6 +133,7 @@ auto configure_single_variant(
         .dry_run = opts.dry_run,
         .verbose = opts.verbose,
         .source_root = ctx.layout().source_root,
+        .config_root = ctx.layout().config_root,
         .output_root = ctx.layout().output_root,
     };
 

src/cli/cmd_parse.cpp

@@ -55,7 +55,7 @@ auto parse_single_variant(Options const& opts, std::string_view variant_name) ->
         for (auto id : commands) {
             if (ctx.graph().get_command_node(id)) {
                 auto display_sv = pup::graph::get_display_str(ctx.graph().graph(), id);
-                auto cmd_sv = pup::graph::expand_instruction(ctx.graph().graph(), id, cache, ctx.layout().source_root);
+                auto cmd_sv = pup::graph::expand_instruction(ctx.graph().graph(), id, cache, ctx.layout().source_root, ctx.layout().config_root);
                 auto label = display_sv.empty() ? cmd_sv : display_sv;
                 printf("[%.*s]   %.*s\n", static_cast<int>(variant_name.size()), variant_name.data(), static_cast<int>(label.size()), label.data());
             }

src/cli/context.cpp

@@ -508,8 +508,6 @@ auto sort_dirs_by_depth(std::set<std::filesystem::path> const& available) -> std
     return dirs;
 }
 
-} // namespace
-
 auto load_ignore_list(ProjectLayout const& layout, bool verbose) -> pup::parser::IgnoreList
 {
     auto ignore = pup::parser::IgnoreList::with_defaults();
@@ -531,6 +529,8 @@ auto load_ignore_list(ProjectLayout const& layout, bool verbose) -> pup::parser:
     return ignore;
 }
 
+} // namespace
+
 auto make_layout_options(Options const& opts) -> LayoutOptions
 {
     auto layout_opts = LayoutOptions {};

src/exec/scheduler.cpp

@@ -821,7 +821,7 @@ auto Scheduler::build_job_list(
         }
 
         // Expand command from instruction pattern + operands
-        auto cmd_str = expand_instruction(graph.graph(), id, cache, impl_->options.source_root);
+        auto cmd_str = expand_instruction(graph.graph(), id, cache, impl_->options.source_root, impl_->options.config_root);
         auto display_str = std::string { get_display_str(graph.graph(), id) };
 
         // Convert exported_vars from StringIds to strings