Support more verbose error reporting

6 files changed, 37 insertions, 3 deletions

diff --git a/share/man/just.1.org b/share/man/just.1.org
index 48cbe25d..14bd8183 100644
--- a/share/man/just.1.org
+++ b/share/man/just.1.org
@@ -339,6 +339,11 @@ well-defined graph file. See *just-graph-file(5)* for more details.
    Log limit (higher is more verbose) in interval [0,6] (Default: 3).\\
    Supported by: analyse|build|describe|install|rebuild|traverse.
 
+   *--expression-log-limit* NUM\\
+   In error messages, truncate the entries in the enumeration of the active
+   environment to the specified number of characters (default: 320).\\
+   Supported by: analyse|build|install
+
    *-P*, *--print-to-stdout* LOGICAL_PATH\\
    After building, print the specified artifact to stdout.\\
 
diff --git a/src/buildtool/build_engine/expression/evaluator.cpp b/src/buildtool/build_engine/expression/evaluator.cpp
index 9789c519..0097bd27 100644
--- a/src/buildtool/build_engine/expression/evaluator.cpp
+++ b/src/buildtool/build_engine/expression/evaluator.cpp
@@ -922,7 +922,7 @@ auto Evaluator::EvaluationError::WhileEvaluating(ExpressionPtr const& expr,
     }
     ss << expr->ToString() << std::endl;
     ss << "  environment " << std::endl;
-    ss << env.Enumerate("  - ", kLineWidth) << std::endl;
+    ss << env.Enumerate("  - ", Config().expression_log_limit) << std::endl;
     ss << ex.what();
     return EvaluationError{ss.str(), true /* while_eval */};
 }
diff --git a/src/buildtool/build_engine/expression/evaluator.hpp b/src/buildtool/build_engine/expression/evaluator.hpp
index b4cd5979..e709de43 100644
--- a/src/buildtool/build_engine/expression/evaluator.hpp
+++ b/src/buildtool/build_engine/expression/evaluator.hpp
@@ -10,7 +10,17 @@
 class Configuration;
 
 class Evaluator {
+    struct ConfigData {
+        std::size_t expression_log_limit{kDefaultExpressionLogLimit};
+    };
+
   public:
+    /// \brief Set the limit for the size of logging a single expression
+    /// in an error message.
+    static void SetExpressionLogLimit(std::size_t width) {
+        Config().expression_log_limit = width;
+    }
+
     class EvaluationError : public std::exception {
       public:
         explicit EvaluationError(std::string const& msg,
@@ -65,12 +75,17 @@ class Evaluator {
         std::function<void(void)> const& note_user_context = []() {}) noexcept
         -> ExpressionPtr;
 
+    constexpr static std::size_t kDefaultExpressionLogLimit = 320;
+
   private:
-    constexpr static std::size_t kLineWidth = 80;
     [[nodiscard]] static auto Evaluate(ExpressionPtr const& expr,
                                        Configuration const& env,
                                        FunctionMapPtr const& functions)
         -> ExpressionPtr;
+    [[nodiscard]] static auto Config() noexcept -> ConfigData& {
+        static ConfigData instance{};
+        return instance;
+    }
 };
 
 #endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP
diff --git a/src/buildtool/common/TARGETS b/src/buildtool/common/TARGETS
index 4f297a12..4cc2dcbf 100644
--- a/src/buildtool/common/TARGETS
+++ b/src/buildtool/common/TARGETS
@@ -3,7 +3,8 @@
   , "name": ["cli"]
   , "hdrs": ["cli.hpp"]
   , "deps":
-    [ ["src/buildtool/compatibility", "compatibility"]
+    [ ["src/buildtool/build_engine/expression", "expression"]
+    , ["src/buildtool/compatibility", "compatibility"]
     , ["src/buildtool/logging", "log_level"]
     , ["@", "cli11", "", "cli11"]
     , ["@", "json", "", "json"]
diff --git a/src/buildtool/common/cli.hpp b/src/buildtool/common/cli.hpp
index adfa3445..b2bd4576 100644
--- a/src/buildtool/common/cli.hpp
+++ b/src/buildtool/common/cli.hpp
@@ -12,6 +12,7 @@
 #include "fmt/core.h"
 #include "gsl-lite/gsl-lite.hpp"
 #include "nlohmann/json.hpp"
+#include "src/buildtool/build_engine/expression/evaluator.hpp"
 #include "src/buildtool/compatibility/compatibility.hpp"
 #include "src/buildtool/logging/log_level.hpp"
 
@@ -30,6 +31,7 @@ struct CommonArguments {
 
 /// \brief Arguments required for analysing targets.
 struct AnalysisArguments {
+    std::optional<std::size_t> expression_log_limit{};
     std::string defines{};
     std::filesystem::path config_file{};
     std::optional<nlohmann::json> target{};
@@ -137,6 +139,12 @@ static inline auto SetupAnalysisArguments(
     gsl::not_null<CLI::App*> const& app,
     gsl::not_null<AnalysisArguments*> const& clargs,
     bool with_graph = true) {
+    app->add_option("--expression-log-limit",
+                    clargs->expression_log_limit,
+                    fmt::format("Maximal size for logging a single expression "
+                                "in error messages (Default {})",
+                                Evaluator::kDefaultExpressionLogLimit))
+        ->type_name("NUM");
     app->add_option(
            "-D,--defines",
            clargs->defines,
diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index d6d999ab..e1630e31 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -15,6 +15,7 @@
 #include "src/buildtool/build_engine/base_maps/rule_map.hpp"
 #include "src/buildtool/build_engine/base_maps/source_map.hpp"
 #include "src/buildtool/build_engine/base_maps/targets_file_map.hpp"
+#include "src/buildtool/build_engine/expression/evaluator.hpp"
 #include "src/buildtool/build_engine/expression/expression.hpp"
 #include "src/buildtool/build_engine/target_map/target_cache.hpp"
 #include "src/buildtool/build_engine/target_map/target_map.hpp"
@@ -1333,6 +1334,10 @@ auto main(int argc, char* argv[]) -> int {
         }
 
         SetupLogging(arguments.common);
+        if (arguments.analysis.expression_log_limit) {
+            Evaluator::SetExpressionLogLimit(
+                *arguments.analysis.expression_log_limit);
+        }
 #ifndef BOOTSTRAP_BUILD_TOOL
         SetupHashFunction();
         SetupExecutionConfig(