From 2191b0d32a59c5f73cadfb30ca473f64e4dfa285 Mon Sep 17 00:00:00 2001
From: firewave <firewave@users.noreply.github.com>
Date: Wed, 5 Nov 2025 15:48:20 +0100
Subject: [PATCH] fixed #504 / refs #507 - cleaned up and improved parsing of
 line preprocessor directive

---
 simplecpp.cpp | 70 ++++++++++++++++++++++++++-------------------------
 test.cpp      | 15 ++++++++++-
 2 files changed, 50 insertions(+), 35 deletions(-)

diff --git a/simplecpp.cpp b/simplecpp.cpp
index dcc534ba..0152a375 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -696,42 +696,44 @@ void simplecpp::TokenList::readfile(Stream &stream, const std::string &filename,
 
             if (oldLastToken != cback()) {
                 oldLastToken = cback();
-                const Token * const llTok = isLastLinePreprocessor();
-                if (!llTok)
+
+                // #line 3
+                // #line 3 "file.c"
+                // #3
+                // #3 "file.c"
+                const Token * ppTok = isLastLinePreprocessor();
+                if (!ppTok)
                     continue;
-                const Token * const llNextToken = llTok->next;
-                if (!llTok->next)
+
+                const auto advanceAndSkipComments = [](const Token* tok) {
+                    do {
+                        tok = tok->next;
+                    } while (tok && tok->comment);
+                    return tok;
+                };
+
+                // skip #
+                ppTok = advanceAndSkipComments(ppTok);
+                if (!ppTok)
                     continue;
-                if (llNextToken->next) {
-                    // TODO: add support for "# 3"
-                    // #3 "file.c"
-                    // #line 3 "file.c"
-                    if ((llNextToken->number &&
-                         llNextToken->next->str()[0] == '\"') ||
-                        (llNextToken->str() == "line" &&
-                         llNextToken->next->number &&
-                         llNextToken->next->next &&
-                         llNextToken->next->next->str()[0] == '\"'))
-                    {
-                        const Token *strtok = cback();
-                        while (strtok->comment)
-                            strtok = strtok->previous;
-                        const Token *numtok = strtok->previous;
-                        while (numtok->comment)
-                            numtok = numtok->previous;
-                        lineDirective(fileIndex(replaceAll(strtok->str().substr(1U, strtok->str().size() - 2U),"\\\\","\\")),
-                                      std::atol(numtok->str().c_str()), location);
-                    }
-                    // #line 3
-                    else if (llNextToken->str() == "line" &&
-                             llNextToken->next->number)
-                    {
-                        const Token *numtok = cback();
-                        while (numtok->comment)
-                            numtok = numtok->previous;
-                        lineDirective(location.fileIndex, std::atol(numtok->str().c_str()), location);
-                    }
-                }
+
+                if (ppTok->str() == "line")
+                    ppTok = advanceAndSkipComments(ppTok);
+
+                if (!ppTok || !ppTok->number)
+                    continue;
+
+                const unsigned int line = std::atol(ppTok->str().c_str());
+                ppTok = advanceAndSkipComments(ppTok);
+
+                unsigned int fileindex;
+
+                if (ppTok && ppTok->str()[0] == '\"')
+                    fileindex = fileIndex(replaceAll(ppTok->str().substr(1U, ppTok->str().size() - 2U),"\\\\","\\"));
+                else
+                    fileindex = location.fileIndex;
+
+                lineDirective(fileindex, line, location);
             }
 
             continue;
diff --git a/test.cpp b/test.cpp
index bebc535d..603d596d 100644
--- a/test.cpp
+++ b/test.cpp
@@ -2413,7 +2413,8 @@ static void location8()
         "# 3\n"
         "__LINE__ __FILE__\n";
     ASSERT_EQUALS("\n"
-                  "2 \"\"", // TODO: should say 3
+                  "\n"
+                  "3 \"\"",
                   preprocess(code));
 }
 
@@ -2454,6 +2455,17 @@ static void location11()
                   preprocess(code));
 }
 
+static void location12()
+{
+    const char code[] =
+        "/**//**/#/**//**/line/**//**/3/**//**/\"file.c\"/**/\n"
+        "__LINE__ __FILE__\n";
+    ASSERT_EQUALS("\n"
+                  "#line 3 \"file.c\"\n"
+                  "3 \"file.c\"",
+                  preprocess(code));
+}
+
 static void missingHeader1()
 {
     const char code[] = "#include \"notexist.h\"\n";
@@ -4060,6 +4072,7 @@ static void runTests(int argc, char **argv, Input input)
     TEST_CASE(location9);
     TEST_CASE(location10);
     TEST_CASE(location11);
+    TEST_CASE(location12);
 
     TEST_CASE(missingHeader1);
     TEST_CASE(missingHeader2);