Fix missing backtick in escape.d error message

[dkorpel]

No description provided.

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[ibuclaw]

@dkorpel FYI, I expect these tests to fail.

FAIL: gdc.test/fail_compilation/retscope2.d   (internal compiler error: in expand_d_format, at d/d-diagnostic.cc:127)
FAIL: gdc.test/fail_compilation/retscope3.d   (internal compiler error: in expand_d_format, at d/d-diagnostic.cc:127)
FAIL: gdc.test/fail_compilation/retscope6.d   (internal compiler error: in expand_d_format, at d/d-diagnostic.cc:127)
FAIL: gdc.test/fail_compilation/test18282.d   (internal compiler error: in expand_d_format, at d/d-diagnostic.cc:127)

[ibuclaw]

Doesn't have to be addressed in this PR, one good way to prevent this from recurring is to copy the strict backtick checking from gdc.

Here is where dmd does backtick highlighting.

dmd/compiler/src/dmd/errors.d

Lines 837 to 871 in ca01894

	private void colorSyntaxHighlight(ref OutBuffer buf)
	{
	//printf("colorSyntaxHighlight('%.*s')\n", cast(int)buf.length, buf[].ptr);
	bool inBacktick = false;
	size_t iCodeStart = 0;
	size_t offset = 0;
	for (size_t i = offset; i < buf.length; ++i)
	{
	char c = buf[i];
	switch (c)
	{
	case '`':
	if (inBacktick)
	{
	inBacktick = false;
	OutBuffer codebuf;
	codebuf.write(buf[iCodeStart .. i]);
	codebuf.writeByte(0);
	// escape the contents, but do not perform highlighting except for DDOC_PSYMBOL
	colorHighlightCode(codebuf);
	buf.remove(iCodeStart, i - iCodeStart);
	immutable pre = "";
	i = buf.insert(iCodeStart, pre);
	i = buf.insert(i, codebuf[]);
	break;
	}
	inBacktick = true;
	iCodeStart = i + 1;
	break;
	default:
	break;
	}
	}
	}

At the end of the function there could be an assert to ensure inBacktick is false.

[dkorpel]

At the end of the function there could be an assert to ensure inBacktick is false.

Wouldn't that trigger when an argument contains a single backtick? For example:

int x = "`";

Error: cannot implicitly convert expression `"`"` of type `string` to `int`

[ibuclaw]

Error: cannot implicitly convert expression ""of typestringtoint`

The format string for that is

cannot implicitly convert expression `%s` of type `%s` to `%s`

So unless highlighting is done after all format specifiers are expanded, then there shouldn't be a problem. Didn't check too closely what dmd is doing.

[dkorpel]

It's doing syntax highlighting after expanding. Also, some messages are formatted with OutBuffer.printf and passed to error() as a single complete string.

[ibuclaw]

Alright, so there's something more fundamentally the issue. Will not push the matter for now then. :-)

BTW, gdc rewrites the format string as:

cannot implicitly convert expression %<%s%> of type %<%s%> to %<%s%>

then gcc has it's own printf-style routines that expand it to the right thing.