Hi!
Trailing blanks is something even git diff diagnoses; while it is a coding
style issue, if it is so common that git diff diagnoses it, I think it could
be useful to various projects to check that at compile time.
Dunno if it should be included in -Wextra, currently it isn't, and due to
tons of trailing whitespace in our sources, haven't enabled it for when
building gcc itself either.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Note, git diff also diagnoses indentation with tab following space, wonder
if we couldn't have trivial warning options where one would simply ask for
checking of indentation with no tabs, just spaces vs. indentation with
tabs followed by spaces (but never tab width or more spaces in the
indentation). I think that would be easy to do also on the libcpp side.
Checking how much something should be exactly indented requires syntax
analysis (at least some limited one) and can consider columns of first token
on line, but what the exact indentation blanks were is something only libcpp
knows.
2024-09-18 Jakub Jelinek <ja...@redhat.com>
libcpp/
* include/cpplib.h (struct cpp_options): Add cpp_warn_trailing_blanks
member.
(enum cpp_warning_reason): Add CPP_W_TRAILING_BLANKS.
* internal.h (struct _cpp_line_note): Document 'B' line note.
* lex.cc (_cpp_clean_line): Add 'B' line note for trailing blanks
except for trailing whitespace after backslash. Formatting fix.
(_cpp_process_line_notes): Emit -Wtrailing-blanks diagnostics.
Formatting fixes.
(lex_raw_string): Clear type on 'B' notes.
gcc/
* doc/invoke.texi (Wtrailing-blanks): Document.
gcc/c-family/
* c.opt (Wtrailing-blanks): New option.
gcc/testsuite/
* c-c++-common/cpp/Wtrailing-blanks.c: New test.
--- libcpp/include/cpplib.h.jj 2024-09-13 16:09:32.690455174 +0200
+++ libcpp/include/cpplib.h 2024-09-18 13:01:26.289338279 +0200
@@ -594,6 +594,9 @@ struct cpp_options
/* True if -finput-charset= option has been used explicitly. */
bool cpp_input_charset_explicit;
+ /* True if -Wtrailing-blanks. */
+ bool cpp_warn_trailing_blanks;
+
/* Dependency generation. */
struct
{
@@ -709,7 +712,8 @@ enum cpp_warning_reason {
CPP_W_EXPANSION_TO_DEFINED,
CPP_W_BIDIRECTIONAL,
CPP_W_INVALID_UTF8,
- CPP_W_UNICODE
+ CPP_W_UNICODE,
+ CPP_W_TRAILING_BLANKS
};
/* Callback for header lookup for HEADER, which is the name of a
--- libcpp/internal.h.jj 2024-09-18 09:45:36.832570227 +0200
+++ libcpp/internal.h 2024-09-18 12:36:04.386099371 +0200
@@ -318,8 +318,8 @@ struct _cpp_line_note
/* Type of note. The 9 'from' trigraph characters represent those
trigraphs, '\\' an escaped newline, ' ' an escaped newline with
- intervening space, 0 represents a note that has already been handled,
- and anything else is invalid. */
+ intervening space, 'B' trailing blanks, 0 represents a note that
+ has already been handled, and anything else is invalid. */
unsigned int type;
};
--- libcpp/lex.cc.jj 2024-09-13 16:09:32.720454758 +0200
+++ libcpp/lex.cc 2024-09-18 14:00:46.344062046 +0200
@@ -928,7 +928,7 @@ _cpp_clean_line (cpp_reader *pfile)
if (p == buffer->next_line || p[-1] != '\\')
break;
- add_line_note (buffer, p - 1, p != d ? ' ': '\\');
+ add_line_note (buffer, p - 1, p != d ? ' ' : '\\');
d = p - 2;
buffer->next_line = p - 1;
}
@@ -943,6 +943,11 @@ _cpp_clean_line (cpp_reader *pfile)
}
}
}
+ done:
+ if (d > buffer->next_line
+ && ISBLANK (d[-1])
+ && CPP_OPTION (pfile, cpp_warn_trailing_blanks))
+ add_line_note (buffer, d - 1, 'B');
}
else
{
@@ -955,7 +960,6 @@ _cpp_clean_line (cpp_reader *pfile)
s++;
}
- done:
*d = '\n';
/* A sentinel note that should never be processed. */
add_line_note (buffer, d + 1, '\n');
@@ -1013,13 +1017,23 @@ _cpp_process_line_notes (cpp_reader *pfi
if (note->type == '\\' || note->type == ' ')
{
- if (note->type == ' ' && !in_comment)
- cpp_error_with_line (pfile, CPP_DL_WARNING,
pfile->line_table->highest_line, col,
- "backslash and newline separated by space");
+ if (note->type == ' ')
+ {
+ if (!in_comment)
+ cpp_error_with_line (pfile, CPP_DL_WARNING,
+ pfile->line_table->highest_line, col,
+ "backslash and newline separated by "
+ "space");
+ else if (CPP_OPTION (pfile, cpp_warn_trailing_blanks))
+ cpp_warning_with_line (pfile, CPP_W_TRAILING_BLANKS,
+ pfile->line_table->highest_line, col,
+ "trailing blanks");
+ }
if (buffer->next_line > buffer->rlimit)
{
- cpp_error_with_line (pfile, CPP_DL_PEDWARN,
pfile->line_table->highest_line, col,
+ cpp_error_with_line (pfile, CPP_DL_PEDWARN,
+ pfile->line_table->highest_line, col,
"backslash-newline at end of file");
/* Prevent "no newline at end of file" warning. */
buffer->next_line = buffer->rlimit;
@@ -1040,15 +1054,16 @@ _cpp_process_line_notes (cpp_reader *pfi
note->type,
(int) _cpp_trigraph_map[note->type]);
else
- {
- cpp_warning_with_line
- (pfile, CPP_W_TRIGRAPHS,
- pfile->line_table->highest_line, col,
- "trigraph ??%c ignored, use -trigraphs to enable",
- note->type);
- }
+ cpp_warning_with_line (pfile, CPP_W_TRIGRAPHS,
+ pfile->line_table->highest_line, col,
+ "trigraph ??%c ignored, use -trigraphs "
+ "to enable", note->type);
}
}
+ else if (note->type == 'B')
+ cpp_warning_with_line (pfile, CPP_W_TRAILING_BLANKS,
+ pfile->line_table->highest_line, col,
+ "trailing blanks");
else if (note->type == 0)
/* Already processed in lex_raw_string. */;
else
@@ -2539,6 +2554,12 @@ lex_raw_string (cpp_reader *pfile, cpp_t
note->type = 0;
note++;
break;
+
+ case 'B':
+ /* Don't warn about trailing blanks in raw string literals. */
+ note->type = 0;
+ note++;
+ break;
default:
gcc_checking_assert (_cpp_trigraph_map[note->type]);
--- gcc/doc/invoke.texi.jj 2024-09-12 18:15:20.458626277 +0200
+++ gcc/doc/invoke.texi 2024-09-18 14:46:39.584782466 +0200
@@ -8996,6 +8996,13 @@ will always be false.
This warning is enabled by @option{-Wall}.
+@opindex Wtrailing-blanks
+@opindex Wno-trailing-blanks
+@item -Wtrailing-blanks
+Warn about trailing blanks (spaces or horizontal tabs) at the end of lines,
+including inside of comments, but excluding trailing blanks in raw string
+literals. This is a coding style warning.
+
@opindex Wtrampolines
@opindex Wno-trampolines
@item -Wtrampolines
--- gcc/c-family/c.opt.jj 2024-09-12 18:15:20.415626861 +0200
+++ gcc/c-family/c.opt 2024-09-18 13:01:56.404927852 +0200
@@ -1450,6 +1450,10 @@ Wtraditional-conversion
C ObjC Var(warn_traditional_conversion) Warning
Warn of prototypes causing type conversions different from what would happen
in the absence of prototype.
+Wtrailing-blanks
+C ObjC C++ ObjC++ CPP(cpp_warn_trailing_blanks)
CppReason(CPP_W_TRAILING_BLANKS) Var(warn_trailing_blanks) Init(0) Warning
+Warn about trailing blanks on lines except when in raw string literals.
+
Wtrigraphs
C ObjC C++ ObjC++ CPP(warn_trigraphs) CppReason(CPP_W_TRIGRAPHS)
Var(cpp_warn_trigraphs) Init(2) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
Warn if trigraphs are encountered that might affect the meaning of the program.
--- gcc/testsuite/c-c++-common/cpp/Wtrailing-blanks.c.jj 2024-09-18
14:44:22.712636656 +0200
+++ gcc/testsuite/c-c++-common/cpp/Wtrailing-blanks.c 2024-09-18
13:21:20.898071467 +0200
@@ -0,0 +1,30 @@
+/* { dg-do compile { target { c || c++11 } } } */
+/* { dg-options "-Wtrailing-blanks" } */
+
+int i;
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-1 } */
+int j;
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-1 } */
+int \
+ k \
+ ;
+/* { dg-warning "backslash and newline separated by space" "" { target *-*-* }
.-3 } */
+/* { dg-warning "backslash and newline separated by space" "" { target *-*-* }
.-3 } */
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-3 } */
+
+
+
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-1 } */
+const char *p = R"*|*(
+
+
+.
+)*|*";
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-1 } */
+// This is a comment with trailing blank
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-1 } */
+/* This is a comment with trailing blanks
+*/
+/* { dg-warning "trailing blanks" "" { target *-*-* } .-2 } */
+/* { dg-warning "trailing blanks" "" { target *-*-* } .+1 } */
+
\ No newline at end of file
Jakub
