Re: [cfe-commits] r59502 - in /cfe/trunk: Driver/ include/clang/Analysis/ include/clang/Analysis/PathSensitive/ include/clang/Basic/ include/clang/Driver/ lib/Analysis/ lib/Basic/ lib/CodeGen/ lib/Driver/ lib/Lex/ lib/Parse/ lib/Sema/

Wed, 19 Nov 2008 21:28:21 -0800

On Nov 18, 2008, at 8:13 AM, Douglas Gregor wrote:
+  DiagnosticInfo &operator<<(const SourceRange &R) {
+    assert((unsigned)DiagObj->NumDiagArgs <
+           sizeof(DiagObj->DiagRanges)/sizeof(DiagObj-
DiagRanges[0]) &&
+           "Too many arguments to diagnostic!");
+    DiagObj->DiagRanges[DiagObj->NumDiagRanges++] = &R;
+    return *this;
+  }
+
};

These operator<<'s should be free functions, because we will certainly  
have other operator<<'s for DiagnosticInfo elsewhere in the compiler  
that must be free functions, e.g.,

DiagnosticInfo& operator<<(DiagnosticInfo& DI, QualType Ty); // in  
clang/AST/Type.h

and we don't want non-member and member operator<<'s overloaded  
because the available conversions on the first argument differ, and  
that causes overloading weirdness.

Yes, I totally agree.  Okay, I'm to the point where I want to do this.  However, this is not my day.  Please take a look at this patch:

Attachment: operators.patch
Description: Binary data


I just move the operators out of the class in a straightforward way.  With this patch, I get build errors like these:

Lexer.cpp: In function ‘char DecodeTrigraphChar(const char*, clang::Lexer*)’:
Lexer.cpp:352: error: no match for ‘operator<<’ in ‘clang::Lexer::Diag(const char*, unsigned int) const((CP - 2u), 9u) << std::operator+(const std::basic_string<_CharT, _Traits, _Alloc>&, _CharT) [with _Char
T = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>](((int)Res))’
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:366: note: candidates are: clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, const std::string&)
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:371: note:                 clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, const char*)
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:376: note:                 clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, int)
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:381: note:                 clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, unsigned int)
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:386: note:                 clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, const clang::IdentifierInfo*)
/Users/sabre/llvm/tools/clang/lib/Lex/../../include/clang/Basic/Diagnostic.h:392: note:                 clang::DiagnosticInfo& clang::operator<<(clang::DiagnosticInfo&, const clang::SourceRange&)

This is the source line:
Lexer *L; char Res;
...
  L->Diag(CP-2, diag::trigraph_converted) << std::string()+Res;

This is a good point where we can step back and look at the amazing awfulness of this diagnostic.  It's 'pretty' printing out the _expression_ in question, in a horribly mangled form.  Then it dumps out a candidate list, but manages to not tell me the types that it actually *has* on the LHS/RHS of the <<.  In practice, I think the problem is that Diag is returning a temporary:

class Lexer {
...
  DiagnosticInfo Diag(const char *Loc, unsigned DiagID) const;

and this isn't matching as the non-constant reference form of <<.  Imagine if it told me that it had near match! :)

All bitching about diagnostics aside, how should I go about fixing this?  Should have hack the overloads to use const references and cast away the const?  Do you have a better suggestion?

-Chris


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