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Fix: simplecpp ## fails to expand function-like macro when '(' is not adjacent #8578

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Fix: simplecpp ## fails to expand function-like macro when '(' is not adjacent #8578

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49 changes: 44 additions & 5 deletions externals/simplecpp/simplecpp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2377,15 +2377,54 @@ namespace simplecpp {
TokenList tokens(files);
tokens.push_back(new Token(strAB, tok->location));
// for function like macros, push the (...)
if (tokensB.empty() && sameline(B,B->next) && B->next->op=='(') {
const MacroMap::const_iterator it = macros.find(strAB);
if (it != macros.end() && expandedmacros.find(strAB) == expandedmacros.end() && it->second.functionLike()) {
const Token * const tok2 = appendTokens(tokens, loc, B->next, macros, expandedmacros, parametertokens);
bool forwardScan = false;
const MacroMap::const_iterator it = macros.find(strAB);
const bool isFunctionLikeMacro = (it != macros.end() && expandedmacros.find(strAB) == expandedmacros.end() && it->second.functionLike());
if (tokensB.empty() && isFunctionLikeMacro) {
// Determine where '(' for the concatenated function-like macro begins.
const Token *lpar = (sameline(B, B->next) && B->next->op == '(') ? B->next : nullptr;
if (!lpar && !expandResult) {
// Forward scan: handles patterns like PAR(PREFIX_ ## kind, (__VA_ARGS__))
// where '(' is not immediately adjacent to B in the replacement text
// but follows comma separators or parameter tokens on the same line.
// Restricted to appendTokens context (expandResult==false) to avoid
// unintended side-effects in the main expansion loop.
const Token *scan = nextTok;
while (scan && sameline(B, scan)) {
if (scan->op == '(') {
// Literal '(' found after skipping separators
lpar = scan;
forwardScan = true;
break;
}
if (scan->op == ',') {
// Skip argument separator and keep scanning
scan = scan->next;
continue;
}
if (scan->name) {
// Named token — check if it's a parameter that expands to '(...)'
TokenList expanded(files);
if (expandArg(expanded, scan, loc, macros, expandedmacros, parametertokens) &&
expanded.cfront() && expanded.cfront()->op == '(') {
for (Token *t = expanded.front(); t; t = t->next)
t->location = loc;
tokens.takeTokens(expanded);
nextTok = scan->next;
forwardScan = true;
}
break; // stop scan at any name token (consumed or not)
}
break; // other operator — stop scan
}
}
if (lpar) {
const Token * const tok2 = appendTokens(tokens, loc, lpar, macros, expandedmacros, parametertokens);
if (tok2)
nextTok = tok2->next;
}
}
if (expandResult)
if (expandResult || forwardScan)
expandToken(output, loc, tokens.cfront(), macros, expandedmacros, parametertokens);
else
output.takeTokens(tokens);
Expand Down
21 changes: 21 additions & 0 deletions test/testpreprocessor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,7 @@ class TestPreprocessor : public TestFixture {
TEST_CASE(preprocessor_undef);
TEST_CASE(defdef); // Defined multiple times
TEST_CASE(preprocessor_doublesharp);
TEST_CASE(preprocessor_doublesharp_funclike_forward_scan); // simplecpp: ## result used as function-like macro via PAR-style indirection
TEST_CASE(preprocessor_include_in_str);
TEST_CASE(va_args_1);
//TEST_CASE(va_args_2); invalid code
Expand Down Expand Up @@ -1355,6 +1356,26 @@ class TestPreprocessor : public TestFixture {
ASSERT_EQUALS("\n\n\n\nx_y", expandMacros(filedata6, *this));
}

// Test for simplecpp forward-scan fix: when ## concatenation produces a function-like macro
// name and '(' is not immediately adjacent in the replacement text (e.g. PAR pattern), the
// forward scan must find '(' across comma separators or parameter tokens on the same line.
void preprocessor_doublesharp_funclike_forward_scan() {
// PAR pattern: PREFIX_ ## kind, (__VA_ARGS__) where '(' is separated by ','
// Previously caused [unknownMacro] and aborted TU analysis in cppcheck.
const char filedata1[] = "#define PAR(a, ...) a __VA_ARGS__\n"
"#define PREFIX_SCALAR(T, N) T N\n"
"#define DISPATCH(kind, ...) PAR(PREFIX_ ## kind, (__VA_ARGS__))\n"
"DISPATCH(SCALAR, int, x)\n";
ASSERT_EQUALS("\n\n\nint x", expandMacros(filedata1, *this));

// Chained: two DISPATCH calls in a struct context
const char filedata2[] = "#define PAR(a, ...) a __VA_ARGS__\n"
"#define PREFIX_SCALAR(T, N) T N\n"
"#define PREFIX_ARRAY(T, N, S) T N[S]\n"
"#define DISPATCH(kind, ...) PAR(PREFIX_ ## kind, (__VA_ARGS__))\n"
"DISPATCH(SCALAR, int, x) DISPATCH(ARRAY, float, arr, 10)\n";
ASSERT_EQUALS("\n\n\n\nint x float arr [ 10 ]", expandMacros(filedata2, *this));
}


void preprocessor_include_in_str() {
Expand Down