search: fix use of cps_path

This must be @Prefix@ prefaced, and is used to describe how the prefix
is calculated when the cps file is passed by path, not to calculate a
prefix which is different than where the cps file is located.

src/cps/loader.cpp

@@ -1,5 +1,5 @@
 // Copyright © 2023-2024 Dylan Baker
-// Copyright © 2024 Bret Brown
+// Copyright © 2024 Dylan Baker
 // SPDX-License-Identifier: MIT
 
 #include "cps/loader.hpp"
@@ -293,8 +293,7 @@ namespace cps::loader {
         auto const name = CPS_TRY(get_required<std::string>(root, "package", "name"));
         auto const cps_version = CPS_TRY(get_required<std::string>(root, "package", "cps_version"));
         auto const components = CPS_TRY(get_required<Components>(root, "package", "components"));
-        auto const cps_path =
-            CPS_TRY(get_optional<std::string>(root, "package", "cps_path")).value_or(filename.parent_path());
+        auto const cps_path = CPS_TRY(get_optional<std::string>(root, "package", "cps_path"));
         auto const default_components =
             CPS_TRY(get_optional<std::vector<std::string>>(root, "package", "default_components"));
         auto const platform = std::nullopt; // TODO: parse platform
@@ -315,6 +314,7 @@ namespace cps::loader {
             .cps_version = std::move(cps_version),
             .components = std::move(components),
             .cps_path = std::move(cps_path),
+            .filename = filename,
             .default_components = std::move(default_components),
             .platform = std::move(platform),
             .require = std::move(require), // requires is a keyword

src/cps/loader.hpp

@@ -135,7 +135,8 @@ namespace cps::loader {
         // TODO: compat-version
         // TODO: configuration
         // TODO: configurations
-        std::string cps_path;
+        std::optional<std::string> cps_path;
+        std::string filename;
         std::optional<std::vector<std::string>> default_components;
         std::optional<Platform> platform;
         Requires require; // Requires is a keyword

src/cps/search.cpp

@@ -309,13 +309,27 @@ namespace cps::search {
             }
         }
 
-        fs::path calculate_prefix(const fs::path & path) {
+        fs::path calculate_prefix(const std::optional<std::string> & path, const fs::path & filename) {
             // TODO: Windows
             // TODO: /cps/<name-like>
-            std::vector<std::string> split = utils::split(std::string{path}, "/");
-            if (split.back() == "") {
-                split.pop_back();
+            if (path) {
+                fs::path p{path.value()};
+                if (p.stem() == "") {
+                    p = p.parent_path();
+                }
+                fs::path f = filename.parent_path();
+                while (p != "@prefix@") {
+                    utils::assert_fn(
+                        p.stem() == f.stem(),
+                        fmt::format("filepath and cps_path have non overlapping stems, prefix: {}, filename {}",
+                                    std::string{p}, std::string{f}));
+                    p = p.parent_path();
+                    f = f.parent_path();
+                }
+                return f;
             }
+
+            std::vector<std::string> split = utils::split(std::string{filename.parent_path()}, "/");
             if (split.back() == "cps") {
                 split.pop_back();
             }
@@ -326,6 +340,7 @@ namespace cps::search {
             if (split.back() == "lib") {
                 split.pop_back();
             }
+
             fs::path p{"/"};
             for (auto && s : split) {
                 p /= s;
@@ -398,20 +413,19 @@ namespace cps::search {
 
         result.version = root->data.package.version.value_or("unknown");
 
-        const auto prefix_path = [&]() -> std::optional<fs::path> {
-            if (prefix_variable) {
-                return fs::path{prefix_variable.value()};
-            }
-            return std::nullopt;
-        }();
+        const auto prefix_path =
+            prefix_variable.has_value() ? std::optional{fs::path{prefix_variable.value()}} : std::nullopt;
 
         for (auto && node : flat) {
 
+            const auto prefix =
+                prefix_path.value_or(calculate_prefix(node->data.package.cps_path, node->data.package.filename));
+
             const auto && prefix_replacer = [&](const std::string & s) -> std::string {
                 // TODO: Windows…
                 auto && split = utils::split(s, "/");
                 if (split[0] == "@prefix@") {
-                    auto p = prefix_path.value_or(calculate_prefix(node->data.package.cps_path));
+                    fs::path p = prefix;
                     for (auto it = split.begin() + 1; it != split.end(); ++it) {
                         p /= *it;
                     }

tests/cases/cps-config.toml

@@ -76,7 +76,13 @@ expected = "-I/err"
 name = "prefix set"
 cps = "cps-path-set"
 args = ["flags", "--cflags-only-I", "--libs-only-l"]
-expected = "-I/sentinel/err -l/sentinel/lib/libfoo.a"
+expected = "-I{prefix}/err -l{prefix}/lib/libfoo.a"
+
+[[case]]
+name = "prefix set (called by path)"
+cps = "{prefix}/cps-path-set.cps"
+args = ["flags", "--cflags-only-I", "--libs-only-l"]
+expected = "-I{prefix}/err -l{prefix}/lib/libfoo.a"
 
 [[case]]
 name = "prefix calculated"

tests/cps-files/lib/cps/cps-path-set.cps

@@ -1,7 +1,7 @@
 {
     "name": "cps-path-set",
     "cps_version": "0.10.0",
-    "cps_path": "/sentinel/lib/cps/",
+    "cps_path": "@prefix@/lib/cps/",
     "version": "1.0.0",
     "components": {
         "default": {

tests/runner.py

@@ -67,7 +67,8 @@ def unordered_compare(out, expected):
     return sorted(out_parts) == sorted(expected_parts)
 
 async def test(runner: str, case_: TestCase) -> Result:
-    cmd = [runner] + case_['args'] + [case_['cps']]
+    cmd = [runner] + case_['args']
+    cmd.append(case_['cps'].replace('{prefix}', os.path.join(PREFIX, 'lib/cps')))
     if 'mode' in case_:
         cmd.extend([f"--format={case_['mode']}"])