From ccdea7d5f756cdd58d1f416ce3d1de36e522f1e4 Mon Sep 17 00:00:00 2001
From: firewave <firewave@users.noreply.github.com>
Date: Sat, 10 Jan 2026 17:14:04 +0100
Subject: [PATCH] fixed #616 - report bad macro syntax via `OutputList`

---
 simplecpp.cpp | 17 +++++++++++++++--
 test.cpp      | 14 ++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/simplecpp.cpp b/simplecpp.cpp
index 62dca039..3a05ec84 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -3341,8 +3341,21 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
             continue;
         const std::string lhs(macrostr.substr(0,eq));
         const std::string rhs(eq==std::string::npos ? std::string("1") : macrostr.substr(eq+1));
-        const Macro macro(lhs, rhs, dummy);
-        macros.insert(std::pair<TokenString,Macro>(macro.name(), macro));
+        try {
+            const Macro macro(lhs, rhs, dummy);
+            macros.insert(std::pair<TokenString,Macro>(macro.name(), macro));
+        } catch (const std::runtime_error& e) {
+            if (outputList) {
+                simplecpp::Output err = {
+                    Output::DUI_ERROR,
+                    {},
+                    e.what()
+                };
+                outputList->push_back(std::move(err));
+            }
+            output.clear();
+            return;
+        }
     }
 
     const bool strictAnsiUndefined = dui.undefined.find("__STRICT_ANSI__") != dui.undefined.cend();
diff --git a/test.cpp b/test.cpp
index 78df4a0e..9583468f 100644
--- a/test.cpp
+++ b/test.cpp
@@ -3442,6 +3442,18 @@ static void tokenlist_api()
 #endif // __cpp_lib_span
 }
 
+static void bad_macro_syntax() // #616
+{
+    simplecpp::DUI dui;
+    dui.defines.emplace_back("\"");
+
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess("", dui, &outputList));
+    ASSERT_EQUALS(1, outputList.size());
+    ASSERT_EQUALS(simplecpp::Output::Type::DUI_ERROR, outputList.cbegin()->type);
+    ASSERT_EQUALS("bad macro syntax. macroname=\" value=1", outputList.cbegin()->msg);
+}
+
 static void isAbsolutePath() {
 #ifdef _WIN32
     ASSERT_EQUALS(true, simplecpp::isAbsolutePath("C:\\foo\\bar"));
@@ -3769,6 +3781,8 @@ int main(int argc, char **argv)
 
     TEST_CASE(isAbsolutePath);
 
+    TEST_CASE(bad_macro_syntax);
+
     TEST_CASE(fuzz_crash);
 
     TEST_CASE(leak);