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Fix #680: Add option to keep comments in preprocessed code #681

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Fix #680: Add option to keep comments in preprocessed code #681

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939c3b8
fix
ludviggunne Jul 13, 2026
8558255
update tests
ludviggunne Jul 13, 2026
04b4e45
add test
ludviggunne Jul 13, 2026
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3 changes: 2 additions & 1 deletion main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -242,7 +242,8 @@ int main(int argc, char **argv)
f.close();
rawtokens = new simplecpp::TokenList(filename,files,&outputList);
}
rawtokens->removeComments();
if (dui.removeComments)
rawtokens->removeComments();
simplecpp::FileDataCache filedata;
simplecpp::preprocess(outputTokens, *rawtokens, files, filedata, dui, &outputList);
simplecpp::cleanup(filedata);
Expand Down
10 changes: 5 additions & 5 deletions simplecpp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3341,7 +3341,7 @@ simplecpp::FileDataCache simplecpp::load(const simplecpp::TokenList &rawtokens,
return cache;
}

static bool preprocessToken(simplecpp::TokenList &output, const simplecpp::Token *&tok1, simplecpp::MacroMap &macros, std::vector<std::string> &files, simplecpp::OutputList *outputList)
static bool preprocessToken(simplecpp::TokenList &output, const simplecpp::Token *&tok1, simplecpp::MacroMap &macros, std::vector<std::string> &files, simplecpp::OutputList *outputList, const simplecpp::DUI &dui)
{
const simplecpp::Token * const tok = tok1;
const simplecpp::MacroMap::const_iterator it = tok->name ? macros.find(tok->str()) : macros.end();
Expand Down Expand Up @@ -3372,7 +3372,7 @@ static bool preprocessToken(simplecpp::TokenList &output, const simplecpp::Token
}
output.takeTokens(value);
} else {
if (!tok->comment)
if (!tok->comment || !dui.removeComments)
output.push_back(new simplecpp::Token(*tok));
tok1 = tok->next;
}
Expand Down Expand Up @@ -3647,7 +3647,7 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
TokenList inc2(files);
if (!inc1.empty() && inc1.cfront()->name) {
const Token *inctok = inc1.cfront();
if (!preprocessToken(inc2, inctok, macros, files, outputList)) {
if (!preprocessToken(inc2, inctok, macros, files, outputList, dui)) {
output.clear();
return;
}
Expand Down Expand Up @@ -3817,7 +3817,7 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
maybeUsedMacros[rawtok->next->str()].emplace_back(rawtok->next->location);

const Token *tmp = tok;
if (!preprocessToken(expr, tmp, macros, files, outputList)) {
if (!preprocessToken(expr, tmp, macros, files, outputList, dui)) {
output.clear();
return;
}
Expand Down Expand Up @@ -3915,7 +3915,7 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
const Location loc(rawtok->location);
TokenList tokens(files);

if (!preprocessToken(tokens, rawtok, macros, files, outputList)) {
if (!preprocessToken(tokens, rawtok, macros, files, outputList, dui)) {
output.clear();
return;
}
Expand Down
37 changes: 33 additions & 4 deletions test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -517,12 +517,15 @@ static void combineOperators_ellipsis()

static void comment()
{
simplecpp::DUI dui;
dui.removeComments = true;

ASSERT_EQUALS("// abc", readfile("// abc"));
ASSERT_EQUALS("", preprocess("// abc"));
ASSERT_EQUALS("", preprocess("// abc", dui));
ASSERT_EQUALS("/*\n\n*/abc", readfile("/*\n\n*/abc"));
ASSERT_EQUALS("\n\nabc", preprocess("/*\n\n*/abc"));
ASSERT_EQUALS("\n\nabc", preprocess("/*\n\n*/abc", dui));
ASSERT_EQUALS("* p = a / * b / * c ;", readfile("*p=a/ *b/ *c;"));
ASSERT_EQUALS("* p = a / * b / * c ;", preprocess("*p=a/ *b/ *c;"));
ASSERT_EQUALS("* p = a / * b / * c ;", preprocess("*p=a/ *b/ *c;", dui));
}

static void comment_multiline()
Expand Down Expand Up @@ -562,6 +565,27 @@ static void comment_multiline()
ASSERT_EQUALS("// abc\ndef", readfile("// abc\\\ndef"));
}

static void keep_comments()
{
simplecpp::DUI dui;
dui.removeComments = false;

{
const char code[] = "/* comment */\n";
ASSERT_EQUALS("/* comment */", preprocess(code,dui));
}

{
const char code[] = "// comment\n";
ASSERT_EQUALS("// comment", preprocess(code,dui));
}

{
const char code[] = "#define MACRO /* comment */\nMACRO\n";
ASSERT_EQUALS("\n/* comment */", preprocess(code,dui));

@danmar danmar Jul 13, 2026

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this may be questionable. do we want that comments are expanded. maybe the comment should only be kept on line 1.

but for now .. as far as I see it does not matter much. If somebody has strong opinions later and wants to change I am not against changing..

}
}


static void constFold()
{
Expand Down Expand Up @@ -2568,13 +2592,16 @@ static void location11()

static void location12()
{
simplecpp::DUI dui;
dui.removeComments = true;

const char code[] =
"/**//**/#/**//**/line/**//**/3/**//**/\"file.c\"/**/\n"
"__LINE__ __FILE__\n";
ASSERT_EQUALS("\n"
"#line 3 \"file.c\"\n"
"3 \"file.c\"",
preprocess(code));
preprocess(code, dui));
}

static void missingHeader1()
Expand Down Expand Up @@ -3012,6 +3039,7 @@ static void include9()
simplecpp::TokenList out(files);
simplecpp::DUI dui;
dui.includePaths.emplace_back(".");
dui.removeComments = true;
simplecpp::preprocess(out, rawtokens_c, files, cache, dui);

ASSERT_EQUALS("\n#line 2 \"1.h\"\nx = 1 ;", out.stringify());
Expand Down Expand Up @@ -4066,6 +4094,7 @@ static void runTests(int argc, char **argv, Input input)

TEST_CASE(comment);
TEST_CASE(comment_multiline);
TEST_CASE(keep_comments);

TEST_CASE(constFold);

Expand Down
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