https://llvm.org/bugs/show_bug.cgi?id=25023
Bug ID: 25023
Summary: Byte order mark (BOM) leads to diagnostic: expected
"FILENAME" or <FILENAME>
Product: clang
Version: 3.7
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: libclang
Assignee: unassignedclangb...@nondot.org
Reporter: nikolai.kos...@theqtcompany.com
CC: kli...@google.com, llvm-bugs@lists.llvm.org
Classification: Unclassified
Created attachment 14978
--> https://llvm.org/bugs/attachment.cgi?id=14978&action=edit
Input files and test program using libclang.
...if CXTranslationUnit_PrecompiledPreamble and clang_reparseTranslationUnit()
is used. The preamble might be truncated due to that.
Consider the UTF-8 source file containing a BOM at the beginning (EF BB BF):
$ cat -v bomfile.cpp
M-oM-;M-?#include <nonExistingHeader.h>
int main() { return 0; }
...and the program making use of libclang, which can be configured to use a
preamble and set the reparse count:
$ cat libclangclient.cpp
#include <clang-c/Index.h>
#include <cstdlib>
#include <cstdio>
int main(int argc, char *argv[])
{
if (argc != 4) {
fprintf(stderr, "Usage: $0 <file> <usePreamble> <reparseCount>\n");
return 0;
}
const bool usePreamble = (argv[2][0] == '1');
int reparseCount = atoi(argv[3]);
CXIndex index = clang_createIndex(0, /*displayDiagnostics*/ 1); // ...to
compare
const unsigned options = usePreamble ?
CXTranslationUnit_PrecompiledPreamble : CXTranslationUnit_None;
CXTranslationUnit tu = clang_parseTranslationUnit(index, argv[1], 0, 0,
NULL, 0, options);
for (;reparseCount; --reparseCount)
clang_reparseTranslationUnit(tu, 0, 0,
clang_defaultReparseOptions(tu));
const unsigned diagnosticCount = clang_getNumDiagnostics(tu);
for(unsigned i = 0; i < diagnosticCount; i++) {
const CXDiagnostic diagnostic = clang_getDiagnostic(tu, i);
const CXSourceLocation location =
clang_getDiagnosticLocation(diagnostic);
unsigned line, column;
clang_getSpellingLocation(location, NULL, &line, &column, NULL);
const CXString text = clang_getDiagnosticSpelling(diagnostic);
fprintf(stderr, "-- Extracted diagnostic: %u:%u: %s\n", line, column,
clang_getCString(text));
clang_disposeString(text);
}
return 0;
}
The output of the program consists of two lines:
* The first line comes from libclang due to clang_createIndex(0,1)
* The second line is generated with the help of clang_getDiagnostic().
Consider the runs with the following configurations:
$ ./libclangclient bomfile.cpp 0 0 # OK, as expected
bomfile.cpp:1:13: fatal error: 'nonExistingHeader.h' file not found
-- Extracted diagnostic: 1:13: 'nonExistingHeader.h' file not found
$ ./libclangclient bomfile.cpp 1 0 # OK, as expected
bomfile.cpp:1:13: fatal error: 'nonExistingHeader.h' file not found
-- Extracted diagnostic: 1:13: 'nonExistingHeader.h' file not found
$ ./libclangclient bomfile.cpp 0 1 # OK, as expected
bomfile.cpp:1:13: fatal error: 'nonExistingHeader.h' file not found
-- Extracted diagnostic: 1:13: 'nonExistingHeader.h' file not found
$ ./libclangclient bomfile.cpp 1 1 # OPS
bomfile.cpp:1:13: fatal error: 'nonExistingHeader.h' file not found
-- Extracted diagnostic: 1:33: expected "FILENAME" or <FILENAME>
$ ./libclangclient bomfile.cpp 1 2 # OPS
bomfile.cpp:1:13: fatal error: 'nonExistingHeader.h' file not found
-- Extracted diagnostic: 1:33: expected "FILENAME" or <FILENAME>
Observations:
(1) As soon as the preamble option is activated and reparse count >= 1 a
misleading diagnostic will be printed. In real world source files with a
BOM much more diagnostics will be generated after that one (as if the
header file was not included...).
(2) Copy bomfile.cpp and append an extra '>' to the include line:
$ ./libclangclient bomfile_with_extra_angle.cpp 1 1
bomfile_with_extra_angle.cpp:1:34: warning: extra tokens at end of
#include directive [-Wextra-tokens]
bomfile_with_extra_angle.cpp:1:13: fatal error: 'nonExistingHeader.h'
file not found
-- Extracted diagnostic: 1:13: 'nonExistingHeader.h' file not found
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