Add additional C flags to your build (improving your code)
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Description
Try to build with the following C flags and improve your code:
-Wall -Wextra -Wconversion -Wcast-align -Wstrict-prototypes -Wuninitialized -Wshadow -Wformat=2 -Werror=incompatible-pointer-types
You will get some nice warnings, function declarations isnt' a prototype, unused-parameters and quite a lot of sign-conversion warnings.
Maybe it's worth looking into those warnings! Those are there for a reason... Those warnings can now be spotted and fixed, improving your code quality.
Small snippet from the output (NOT the full output):
[build] ../lib/commonmarker/src/buffer.c:161:39: note: in expansion of macro ‘MIN’
[build] 161 | int result = memcmp(a->ptr, b->ptr, MIN(a->size, b->size));
[build] | ^~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_strchr’:
[build] ../lib/commonmarker/src/buffer.c:173:60: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 173 | (unsigned char *)memchr(buf->ptr + pos, c, buf->size - pos);
[build] | ~~~~~~~~~~^~~~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_drop’:
[build] ../lib/commonmarker/src/buffer.c:211:42: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 211 | memmove(buf->ptr, buf->ptr + n, buf->size);
[build] | ~~~^~~~~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_rtrim’:
[build] ../lib/commonmarker/src/buffer.c:222:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 222 | if (!cmark_isspace(buf->ptr[buf->size - 1]))
[build] | ~~~~~~~~^~~~~~~~~~~~~~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_trim’:
[build] ../lib/commonmarker/src/buffer.c:237:49: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 237 | while (i < buf->size && cmark_isspace(buf->ptr[i]))
[build] | ~~~~~~~~^~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_normalize_whitespace’:
[build] ../lib/commonmarker/src/buffer.c:252:29: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 252 | if (cmark_isspace(s->ptr[r])) {
[build] | ~~~~~~^~~
[build] ../lib/commonmarker/src/buffer.c: In function ‘cmark_strbuf_unescape’:
[build] ../lib/commonmarker/src/buffer.c:271:54: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 271 | if (buf->ptr[r] == '\\' && cmark_ispunct(buf->ptr[r + 1]))
[build] | ~~~~~~~~^~~~~~~
[build] [41/58 58% :: 0.717] Building C object lib/whereami/CMakeFiles/whereami.dir/whereami.c.o
[build] ../lib/whereami/whereami.c: In function ‘wai_getExecutablePath’:
[build] ../lib/whereami/whereami.c:204:29: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 204 | memcpy(out, resolved, length);
[build] | ^~~~~~
[build] ../lib/whereami/whereami.c: In function ‘wai_getModulePath’:
[build] ../lib/whereami/whereami.c:329:35: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 329 | memcpy(out, resolved, length);
[build] | ^~~~~~
[build] [42/58 60% :: 0.731] Building C object lib/commonmarker/src/CMakeFiles/LibCommonMarker.dir/references.c.o
[build] In file included from ../lib/commonmarker/src/references.c:1:
[build] ../lib/commonmarker/src/cmark-gfm.h:114:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
[build] 114 | cmark_mem *cmark_get_default_mem_allocator();
[build] | ^~~~~~~~~
[build] ../lib/commonmarker/src/cmark-gfm.h:120:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
[build] 120 | cmark_mem *cmark_get_arena_mem_allocator();
[build] | ^~~~~~~~~
[build] In file included from ../lib/commonmarker/src/map.h:4,
[build] from ../lib/commonmarker/src/references.h:4,
[build] from ../lib/commonmarker/src/parser.h:5,
[build] from ../lib/commonmarker/src/references.c:2:
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_ltrim’:
[build] ../lib/commonmarker/src/chunk.h:32:41: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 32 | while (c->len && cmark_isspace(c->data[0])) {
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_rtrim’:
[build] ../lib/commonmarker/src/chunk.h:42:31: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 42 | if (!cmark_isspace(c->data[c->len - 1]))
[build] | ~~~~~~~^~~~~~~~~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_strchr’:
[build] ../lib/commonmarker/src/chunk.h:57:61: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 57 | (unsigned char *)memchr(ch->data + offset, c, ch->len - offset);
[build] | ~~~~~~~~^~~~~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_to_cstr’:
[build] ../lib/commonmarker/src/chunk.h:68:45: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 68 | str = (unsigned char *)mem->calloc(c->len + 1, 1);
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h:70:27: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 70 | memcpy(str, c->data, c->len);
[build] | ~^~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_set_cstr’:
[build] ../lib/commonmarker/src/chunk.h:88:51: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 88 | c->data = (unsigned char *)mem->calloc(c->len + 1, 1);
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h:90:33: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 90 | memcpy(c->data, str, c->len + 1);
[build] | ~~~~~~~^~~
[build] [42/58 62% :: 0.770] Linking C static library lib/whereami/libwhereami.a
[build] [42/58 63% :: 0.884] Building C object lib/commonmarker/src/CMakeFiles/LibCommonMarker.dir/blocks.c.o
[build] In file included from ../lib/commonmarker/src/syntax_extension.h:4,
[build] from ../lib/commonmarker/src/blocks.c:13:
[build] ../lib/commonmarker/src/cmark-gfm.h:114:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
[build] 114 | cmark_mem *cmark_get_default_mem_allocator();
[build] | ^~~~~~~~~
[build] ../lib/commonmarker/src/cmark-gfm.h:120:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
[build] 120 | cmark_mem *cmark_get_arena_mem_allocator();
[build] | ^~~~~~~~~
[build] In file included from ../lib/commonmarker/src/map.h:4,
[build] from ../lib/commonmarker/src/references.h:4,
[build] from ../lib/commonmarker/src/parser.h:5,
[build] from ../lib/commonmarker/src/blocks.c:15:
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_ltrim’:
[build] ../lib/commonmarker/src/chunk.h:32:41: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 32 | while (c->len && cmark_isspace(c->data[0])) {
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_rtrim’:
[build] ../lib/commonmarker/src/chunk.h:42:31: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 42 | if (!cmark_isspace(c->data[c->len - 1]))
[build] | ~~~~~~~^~~~~~~~~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_strchr’:
[build] ../lib/commonmarker/src/chunk.h:57:61: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 57 | (unsigned char *)memchr(ch->data + offset, c, ch->len - offset);
[build] | ~~~~~~~~^~~~~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_to_cstr’:
[build] ../lib/commonmarker/src/chunk.h:68:45: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 68 | str = (unsigned char *)mem->calloc(c->len + 1, 1);
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h:70:27: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘bufsize_t’ {aka ‘int’} may change the sign of the result [-Wsign-conversion]
[build] 70 | memcpy(str, c->data, c->len);
[build] | ~^~~~~
[build] ../lib/commonmarker/src/chunk.h: In function ‘cmark_chunk_set_cstr’:
[build] ../lib/commonmarker/src/chunk.h:88:51: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 88 | c->data = (unsigned char *)mem->calloc(c->len + 1, 1);
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/chunk.h:90:33: warning: conversion to ‘size_t’ {aka ‘long unsigned int’} from ‘int’ may change the sign of the result [-Wsign-conversion]
[build] 90 | memcpy(c->data, str, c->len + 1);
[build] | ~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c: In function ‘S_set_last_line_blank’:
[build] ../lib/commonmarker/src/blocks.c:51:20: warning: conversion from ‘int’ to ‘uint16_t’ {aka ‘short unsigned int’} may change value [-Wconversion]
[build] 51 | node->flags &= ~CMARK_NODE__LAST_LINE_BLANK;
[build] | ^
[build] ../lib/commonmarker/src/blocks.c: In function ‘remove_trailing_blank_lines’:
[build] ../lib/commonmarker/src/blocks.c:221:54: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 221 | if (c != ' ' && c != '\t' && !S_is_line_end_char(c))
[build] | ^
[build] ../lib/commonmarker/src/blocks.c:233:29: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 233 | if (!S_is_line_end_char(c))
[build] | ^
[build] ../lib/commonmarker/src/blocks.c: In function ‘finalize’:
[build] ../lib/commonmarker/src/blocks.c:284:15: warning: conversion from ‘int’ to ‘uint16_t’ {aka ‘short unsigned int’} may change value [-Wconversion]
[build] 284 | b->flags &= ~CMARK_NODE__OPEN;
[build] | ^
[build] ../lib/commonmarker/src/blocks.c:324:49: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 324 | if (S_is_line_end_char(node_content->ptr[pos]))
[build] | ~~~~~~~~~~~~~~~~~^~~~~
[build] ../lib/commonmarker/src/blocks.c: In function ‘parse_list_marker’:
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:555:24: note: in expansion of macro ‘peek_at’
[build] 555 | if (!cmark_isspace(peek_at(input, pos))) {
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:562:32: note: in expansion of macro ‘peek_at’
[build] 562 | while (S_is_space_or_tab(peek_at(input, i))) {
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c:577:28: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 577 | } else if (cmark_isdigit(c)) {
[build] | ^
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:588:42: note: in expansion of macro ‘peek_at’
[build] 588 | } while (digits < 9 && cmark_isdigit(peek_at(input, pos)));
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:596:26: note: in expansion of macro ‘peek_at’
[build] 596 | if (!cmark_isspace(peek_at(input, pos))) {
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:602:34: note: in expansion of macro ‘peek_at’
[build] 602 | while (S_is_space_or_tab(peek_at(input, i))) {
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c:33:32: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 33 | #define peek_at(i, n) (i)->data[n]
[build] | ~~~~~~~~~^~~
[build] ../lib/commonmarker/src/blocks.c:605:32: note: in expansion of macro ‘peek_at’
[build] 605 | if (S_is_line_end_char(peek_at(input, i))) {
[build] | ^~~~~~~
[build] ../lib/commonmarker/src/blocks.c: In function ‘S_parser_feed’:
[build] ../lib/commonmarker/src/blocks.c:711:30: warning: conversion to ‘char’ from ‘unsigned char’ may change the sign of the result [-Wsign-conversion]
[build] 711 | if (S_is_line_end_char(*eol)) {
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the warning output with the listed compiler flags, then review the examples in lib/commonmarker/src/buffer.c, cmark-gfm.h, chunk.h, blocks.c, and lib/whereami/whereami.c. Inspect the complete build output to identify the remaining warnings and determine which are appropriate to fix. Done means the relevant warnings are addressed and the project still builds and tests successfully.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c
- Domain
- build-system
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100