diff options
Diffstat (limited to 'gcc/c-family/c-common.c')
| -rw-r--r-- | gcc/c-family/c-common.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 09594e4..dfcfb19 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -7946,6 +7946,164 @@ c_flt_eval_method (bool maybe_c11_only_p) return c_ts18661_flt_eval_method (); } +/* An enum for get_missing_token_insertion_kind for describing the best + place to insert a missing token, if there is one. */ + +enum missing_token_insertion_kind +{ + MTIK_IMPOSSIBLE, + MTIK_INSERT_BEFORE_NEXT, + MTIK_INSERT_AFTER_PREV +}; + +/* Given a missing token of TYPE, determine if it is reasonable to + emit a fix-it hint suggesting the insertion of the token, and, + if so, where the token should be inserted relative to other tokens. + + It only makes sense to do this for values of TYPE that are symbols. + + Some symbols should go before the next token, e.g. in: + if flag) + we want to insert the missing '(' immediately before "flag", + giving: + if (flag) + rather than: + if( flag) + These use MTIK_INSERT_BEFORE_NEXT. + + Other symbols should go after the previous token, e.g. in: + if (flag + do_something (); + we want to insert the missing ')' immediately after the "flag", + giving: + if (flag) + do_something (); + rather than: + if (flag + )do_something (); + These use MTIK_INSERT_AFTER_PREV. */ + +static enum missing_token_insertion_kind +get_missing_token_insertion_kind (enum cpp_ttype type) +{ + switch (type) + { + /* Insert missing "opening" brackets immediately + before the next token. */ + case CPP_OPEN_SQUARE: + case CPP_OPEN_PAREN: + return MTIK_INSERT_BEFORE_NEXT; + + /* Insert other missing symbols immediately after + the previous token. */ + case CPP_CLOSE_PAREN: + case CPP_CLOSE_SQUARE: + case CPP_SEMICOLON: + case CPP_COMMA: + case CPP_COLON: + return MTIK_INSERT_AFTER_PREV; + + /* Other kinds of token don't get fix-it hints. */ + default: + return MTIK_IMPOSSIBLE; + } +} + +/* Given RICHLOC, a location for a diagnostic describing a missing token + of kind TOKEN_TYPE, potentially add a fix-it hint suggesting the + insertion of the token. + + The location of the attempted fix-it hint depends on TOKEN_TYPE: + it will either be: + (a) immediately after PREV_TOKEN_LOC, or + + (b) immediately before the primary location within RICHLOC (taken to + be that of the token following where the token was expected). + + If we manage to add a fix-it hint, then the location of the + fix-it hint is likely to be more useful as the primary location + of the diagnostic than that of the following token, so we swap + these locations. + + For example, given this bogus code: + 123456789012345678901234567890 + 1 | int missing_semicolon (void) + 2 | { + 3 | return 42 + 4 | } + + we will emit: + + "expected ';' before '}'" + + RICHLOC's primary location is at the closing brace, so before "swapping" + we would emit the error at line 4 column 1: + + 123456789012345678901234567890 + 3 | return 42 |< fix-it hint emitted for this line + | ; | + 4 | } |< "expected ';' before '}'" emitted at this line + | ^ | + + It's more useful for the location of the diagnostic to be at the + fix-it hint, so we swap the locations, so the primary location + is at the fix-it hint, with the old primary location inserted + as a secondary location, giving this, with the error at line 3 + column 12: + + 123456789012345678901234567890 + 3 | return 42 |< "expected ';' before '}'" emitted at this line, + | ^ | with fix-it hint + 4 | ; | + | } |< secondary range emitted here + | ~ |. */ + +void +maybe_suggest_missing_token_insertion (rich_location *richloc, + enum cpp_ttype token_type, + location_t prev_token_loc) +{ + gcc_assert (richloc); + + enum missing_token_insertion_kind mtik + = get_missing_token_insertion_kind (token_type); + + switch (mtik) + { + default: + gcc_unreachable (); + break; + + case MTIK_IMPOSSIBLE: + return; + + case MTIK_INSERT_BEFORE_NEXT: + /* Attempt to add the fix-it hint before the primary location + of RICHLOC. */ + richloc->add_fixit_insert_before (cpp_type2name (token_type, 0)); + break; + + case MTIK_INSERT_AFTER_PREV: + /* Attempt to add the fix-it hint after PREV_TOKEN_LOC. */ + richloc->add_fixit_insert_after (prev_token_loc, + cpp_type2name (token_type, 0)); + break; + } + + /* If we were successful, use the fix-it hint's location as the + primary location within RICHLOC, adding the old primary location + back as a secondary location. */ + if (!richloc->seen_impossible_fixit_p ()) + { + fixit_hint *hint = richloc->get_last_fixit_hint (); + location_t hint_loc = hint->get_start_loc (); + location_t old_loc = richloc->get_loc (); + + richloc->set_range (line_table, 0, hint_loc, true); + richloc->add_range (old_loc, false); + } +} + #if CHECKING_P namespace selftest { |