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[c99, cpp]: Use fallthrough attribute #709

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[c99, cpp]: Use fallthrough attribute #709

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0aac7c3
Avoid case fallthrough before case terminate
lb90 Jul 19, 2025
f85c324
[c99, cpp]: Use fallthrough attribute
lb90 Jul 18, 2025
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14 changes: 13 additions & 1 deletion src/c99-flex.skl
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,19 @@ m4_define([[M4_HOOK_STATE_ENTRY_FORMAT]], [[ &yy_transition[$1],
]])
m4_define([[M4_HOOK_NORMAL_STATE_CASE_ARM]], [[ case $1:]])
m4_define([[M4_HOOK_EOF_STATE_CASE_ARM]], [[ case YY_STATE_EOF($1):]])
m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[ /* FALLTHROUGH */]])
m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[
m4_changequote(<<, >>)
#if defined(__has_c_attribute)
#if __has_c_attribute(fallthrough)
[[fallthrough]];
#endif
#elif defined(__has_attribute)
#if __has_attribute (fallthrough)
__attribute__((fallthrough));
#endif
#endif
m4_changequote([[, ]])
]])
m4_define([[M4_HOOK_EOF_STATE_CASE_TERMINATE]], [[ yyterminate();
]])
m4_define([[M4_HOOK_TAKE_YYTEXT]], [[yy_do_before_action(yyscanner, yy_cp, yy_bp); /* set up yytext */]])
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14 changes: 13 additions & 1 deletion src/cpp-flex.skl
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,19 @@ m4_define([[M4_HOOK_STATE_ENTRY_FORMAT]], [[ &yy_transition[$1],
]])
m4_define([[M4_HOOK_NORMAL_STATE_CASE_ARM]], [[ case $1:]])
m4_define([[M4_HOOK_EOF_STATE_CASE_ARM]], [[ case YY_STATE_EOF($1):]])
m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[ /* FALLTHROUGH */]])
m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[
m4_changequote(<<, >>)
#if defined(__has_cpp_attribute)
#if __has_cpp_attribute(fallthrough)
[[fallthrough]];
#endif
#elif defined(__has_attribute)
#if __has_attribute (fallthrough)
__attribute__((fallthrough));
#endif
#endif
m4_changequote([[, ]])
]])
m4_define([[M4_HOOK_EOF_STATE_CASE_TERMINATE]], [[ yyterminate();
]])
m4_define([[M4_HOOK_TAKE_YYTEXT]], [[YY_DO_BEFORE_ACTION; /* set up yytext */]])
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6 changes: 4 additions & 2 deletions src/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -239,10 +239,12 @@ int flex_main (int argc, char *argv[])
/* generate cases for any missing EOF rules */
for (i = 1; i <= lastsc; ++i)
if (!sceof[i]) {
if (did_eof_rule) {
out ("M4_HOOK_EOF_STATE_CASE_FALLTHROUGH");
outc('\n');
}
out_str ("M4_HOOK_EOF_STATE_CASE_ARM(%s)", scname[i]);
outc('\n');
out ("M4_HOOK_EOF_STATE_CASE_FALLTHROUGH");
outc('\n');
did_eof_rule = true;
}

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