Bug #:
Submitted by:
Reviewed by:
The following code illustrates a bug in the semantic analysis for assignments:
int func() {
int *P;
char *x;
P = x; // type of this assignment expression should be "int *", NOT "char *".
}
While the type checking/diagnostics are correct, the type of the assignment
expression is incorrect (which shows up during code gen). With the fix,
the llvm code looks correct...
[dylan:~/llvm/tools/clang] admin% ../../Debug/bin/clang cast.c -emit-llvm
cast.c:4:5: warning: incompatible pointer types assigning 'char *' to 'int *'
P = x; // type of assignment expression is "int *", NOT "char *".
~ ^ ~
; ModuleID = 'foo'
define i32 @func() {
entry:
%P = alloca i32* ; <i32**> [#uses=1]
%x = alloca i8* ; <i8**> [#uses=1]
%allocapt = bitcast i32 undef to i32 ; <i32> [#uses=0]
%tmp = load i8** %x ; <i8*> [#uses=1]
%conv = bitcast i8* %tmp to i32* ; <i32*> [#uses=1]
store i32* %conv, i32** %P
ret i32 undef
}
Even though the fix was simple, I decided to rename/refactor the surrounding code
to make a clearer distinction between constraint checking and conversion.
- Renamed AssignmentConversionResult -> AssignmentCheckResult.
- Renamed UsualAssignmentConversions -> CheckAssignmentConstraints.
- Changed the return type of CheckAssignmentConstraints and CheckPointerTypesForAssignment
from QualType -> AssignmentCheckResult. These routines no longer take a reference to the result (obviously).
- Changed CheckAssignmentOperands to return the correct type (with spec annotations).
llvm-svn: 39601
This commit is contained in:
Steve Naroff
parent
2e550fea6a
commit
98cf3e95ce
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@ -273,7 +273,7 @@ private:
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// or array, this routine simply returns the input type (unmodified).
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QualType DefaultFunctionArrayConversion(QualType t);
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enum AssignmentConversionResult {
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enum AssignmentCheckResult {
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Compatible,
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Incompatible,
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PointerFromInt,
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@ -281,14 +281,13 @@ private:
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IncompatiblePointer,
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CompatiblePointerDiscardsQualifiers
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};
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// UsualAssignmentConversions - conversions for assignment, argument passing,
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// CheckAssignmentConstraints - conversions for assignment, argument passing,
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// variable initialization, and function return values. Currently used by
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// CheckAssignmentOperands, ParseCallExpr, and ParseReturnStmt.
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QualType UsualAssignmentConversions(QualType lhs, QualType rhs, // C99 6.5.16
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AssignmentConversionResult &r);
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// Helper function for UsualAssignmentConversions (C99 6.5.16.1p1)
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QualType CheckPointerTypesForAssignment(QualType lhsType, QualType rhsType,
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AssignmentConversionResult &r);
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// CheckAssignmentOperands, ParseCallExpr, and ParseReturnStmt. C99 6.5.16.
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AssignmentCheckResult CheckAssignmentConstraints(QualType lhs, QualType rhs);
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// Helper function for CheckAssignmentConstraints (C99 6.5.16.1p1)
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AssignmentCheckResult CheckPointerTypesForAssignment(QualType lhsType,
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QualType rhsType);
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/// the following "Check" methods will return a valid/converted QualType
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/// or a null QualType (indicating an error diagnostic was issued).
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@ -415,9 +415,9 @@ ParseCallExpr(ExprTy *Fn, SourceLocation LParenLoc,
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if (lhsType == rhsType) // common case, fast path...
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continue;
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AssignmentConversionResult result;
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UsualAssignmentConversions(lhsType, rhsType, result);
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AssignmentCheckResult result = CheckAssignmentConstraints(lhsType,
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rhsType);
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SourceLocation l = argExpr->getLocStart();
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// decode the result (notice that AST's are still created for extensions).
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@ -634,9 +634,8 @@ QualType Sema::UsualArithmeticConversions(QualType t1, QualType t2) {
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// routine is it effectively iqnores the qualifiers on the top level pointee.
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// This circumvents the usual type rules specified in 6.2.7p1 & 6.7.5.[1-3].
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// FIXME: add a couple examples in this comment.
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QualType Sema::CheckPointerTypesForAssignment(QualType lhsType,
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QualType rhsType,
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AssignmentConversionResult &r) {
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Sema::AssignmentCheckResult
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Sema::CheckPointerTypesForAssignment(QualType lhsType, QualType rhsType) {
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QualType lhptee, rhptee;
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// get the "pointed to" type (ignoring qualifiers at the top level)
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@ -647,6 +646,8 @@ QualType Sema::CheckPointerTypesForAssignment(QualType lhsType,
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lhptee = lhptee.getCanonicalType();
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rhptee = rhptee.getCanonicalType();
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AssignmentCheckResult r = Compatible;
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// C99 6.5.16.1p1: This following citation is common to constraints
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// 3 & 4 (below). ...and the type *pointed to* by the left has all the
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// qualifiers of the type *pointed to* by the right;
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@ -668,10 +669,10 @@ QualType Sema::CheckPointerTypesForAssignment(QualType lhsType,
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else if (!Type::typesAreCompatible(lhptee.getUnqualifiedType(),
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rhptee.getUnqualifiedType()))
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r = IncompatiblePointer; // this "trumps" PointerAssignDiscardsQualifiers
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return rhsType;
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return r;
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}
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/// UsualAssignmentConversions (C99 6.5.16) - This routine currently
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/// CheckAssignmentConstraints (C99 6.5.16) - This routine currently
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/// has code to accommodate several GCC extensions when type checking
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/// pointers. Here are some objectionable examples that GCC considers warnings:
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///
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@ -688,44 +689,37 @@ QualType Sema::CheckPointerTypesForAssignment(QualType lhsType,
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/// C99 spec dictates.
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/// Note: the warning above turn into errors when -pedantic-errors is enabled.
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///
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QualType Sema::UsualAssignmentConversions(QualType lhsType, QualType rhsType,
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AssignmentConversionResult &r) {
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Sema::AssignmentCheckResult
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Sema::CheckAssignmentConstraints(QualType lhsType, QualType rhsType) {
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// This check seems unnatural, however it is necessary to insure the proper
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// conversion of functions/arrays. If the conversion were done for all
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// DeclExpr's (created by ParseIdentifierExpr), it would mess up the unary
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// expressions that surpress this implicit conversion (&, sizeof).
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rhsType = DefaultFunctionArrayConversion(rhsType);
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r = Compatible;
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if (lhsType->isArithmeticType() && rhsType->isArithmeticType())
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return lhsType;
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return Compatible;
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else if (lhsType->isPointerType()) {
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if (rhsType->isIntegerType()) {
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r = PointerFromInt;
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return rhsType;
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}
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if (rhsType->isIntegerType())
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return PointerFromInt;
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if (rhsType->isPointerType())
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return CheckPointerTypesForAssignment(lhsType, rhsType, r);
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return CheckPointerTypesForAssignment(lhsType, rhsType);
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} else if (rhsType->isPointerType()) {
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if (lhsType->isIntegerType()) {
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// C99 6.5.16.1p1: the left operand is _Bool and the right is a pointer.
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if (lhsType != Context.BoolTy)
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r = IntFromPointer;
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return rhsType;
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}
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// C99 6.5.16.1p1: the left operand is _Bool and the right is a pointer.
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if ((lhsType->isIntegerType()) && (lhsType != Context.BoolTy))
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return IntFromPointer;
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if (lhsType->isPointerType())
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return CheckPointerTypesForAssignment(lhsType, rhsType, r);
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return CheckPointerTypesForAssignment(lhsType, rhsType);
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} else if (isa<TagType>(lhsType) && isa<TagType>(rhsType)) {
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if (Type::tagTypesAreCompatible(lhsType, rhsType))
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return rhsType;
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return Compatible;
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} else if (lhsType->isReferenceType() || rhsType->isReferenceType()) {
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if (Type::referenceTypesAreCompatible(lhsType, rhsType))
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// C++ 5.17p1: ...the type of the assignment exression is that of its left
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// operand.
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return lhsType;
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return Compatible;
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}
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r = Incompatible;
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return QualType();
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return Incompatible;
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}
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inline void Sema::InvalidOperands(SourceLocation loc, Expr *lex, Expr *rex) {
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@ -898,8 +892,7 @@ inline QualType Sema::CheckAssignmentOperands( // C99 6.5.16.1
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if (lhsType == rhsType) // common case, fast path...
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return lhsType;
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AssignmentConversionResult result;
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QualType resType = UsualAssignmentConversions(lhsType, rhsType, result);
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AssignmentCheckResult result = CheckAssignmentConstraints(lhsType, rhsType);
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// decode the result (notice that extensions still return a type).
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switch (result) {
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@ -935,7 +928,13 @@ inline QualType Sema::CheckAssignmentOperands( // C99 6.5.16.1
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lex->getSourceRange(), rex->getSourceRange());
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break;
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}
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return hadError ? QualType() : resType;
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// C99 6.5.16p3: The type of an assignment expression is the type of the
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// left operand unless the left operand has qualified type, in which case
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// it is the unqualified version of the type of the left operand.
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// C99 6.5.16.1p2: In simple assignment, the value of the right operand
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// is converted to the type of the assignment expression (above).
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// C++ 5.17p1: the type of the assignment expression is that of its left oprdu.
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return hadError ? QualType() : lhsType.getUnqualifiedType();
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}
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inline QualType Sema::CheckCommaOperands( // C99 6.5.17
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@ -241,8 +241,7 @@ Sema::ParseReturnStmt(SourceLocation ReturnLoc, ExprTy *RetValExp) {
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// C99 6.8.6.4p3(136): The return statement is not an assignment. The
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// overlap restriction of subclause 6.5.16.1 does not apply to the case of
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// function return.
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AssignmentConversionResult result;
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QualType resType = UsualAssignmentConversions(lhsType, rhsType, result);
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AssignmentCheckResult result = CheckAssignmentConstraints(lhsType, rhsType);
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bool hadError = false;
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// decode the result (notice that extensions still return a type).
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@ -10,6 +10,8 @@
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1A30A9E90B93A4C800201A91 /* ExprCXX.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = 1A30A9E80B93A4C800201A91 /* ExprCXX.h */; };
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1A869A700BA2164C008DA07A /* LiteralSupport.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = 1A869A6E0BA2164C008DA07A /* LiteralSupport.h */; };
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1A869AA80BA21ABA008DA07A /* LiteralSupport.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 1A869AA70BA21ABA008DA07A /* LiteralSupport.cpp */; };
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84916BE50C161E580080778F /* Attr.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 84916BE40C161E580080778F /* Attr.cpp */; };
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84916BE70C161E800080778F /* Attr.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = 84916BE60C161E800080778F /* Attr.h */; };
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DE01DA490B12ADA300AC22CE /* PPCallbacks.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = DE01DA480B12ADA300AC22CE /* PPCallbacks.h */; };
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DE06756C0C051CFE00EBBFD8 /* ParseExprCXX.cpp in Sources */ = {isa = PBXBuildFile; fileRef = DE06756B0C051CFE00EBBFD8 /* ParseExprCXX.cpp */; };
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DE06B73E0A8307640050E87E /* LangOptions.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = DE06B73D0A8307640050E87E /* LangOptions.h */; };
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@ -106,6 +108,23 @@
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DED7D9E50A5257F6003AD0FB /* ScratchBuffer.cpp in Sources */ = {isa = PBXBuildFile; fileRef = DED7D9E40A5257F6003AD0FB /* ScratchBuffer.cpp */; };
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/* End PBXBuildFile section */
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/* Begin PBXBuildStyle section */
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84916C3B0C1736920080778F /* Development */ = {
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isa = PBXBuildStyle;
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buildSettings = {
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COPY_PHASE_STRIP = NO;
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};
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name = Development;
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};
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84916C3C0C1736920080778F /* Deployment */ = {
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isa = PBXBuildStyle;
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buildSettings = {
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COPY_PHASE_STRIP = YES;
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};
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name = Deployment;
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};
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/* End PBXBuildStyle section */
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/* Begin PBXCopyFilesBuildPhase section */
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8DD76F690486A84900D96B5E /* CopyFiles */ = {
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isa = PBXCopyFilesBuildPhase;
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@ -160,6 +179,7 @@
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DE928B200C0565B000231DA4 /* ModuleBuilder.h in CopyFiles */,
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DE928B7D0C0A615100231DA4 /* CodeGenModule.h in CopyFiles */,
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DE928B810C0A615B00231DA4 /* CodeGenFunction.h in CopyFiles */,
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84916BE70C161E800080778F /* Attr.h in CopyFiles */,
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);
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runOnlyForDeploymentPostprocessing = 1;
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};
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@ -169,6 +189,8 @@
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1A30A9E80B93A4C800201A91 /* ExprCXX.h */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.c.h; name = ExprCXX.h; path = clang/AST/ExprCXX.h; sourceTree = "<group>"; };
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1A869A6E0BA2164C008DA07A /* LiteralSupport.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = LiteralSupport.h; sourceTree = "<group>"; };
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1A869AA70BA21ABA008DA07A /* LiteralSupport.cpp */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.cpp; path = LiteralSupport.cpp; sourceTree = "<group>"; };
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84916BE40C161E580080778F /* Attr.cpp */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.cpp; name = Attr.cpp; path = AST/Attr.cpp; sourceTree = "<group>"; };
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84916BE60C161E800080778F /* Attr.h */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.c.h; name = Attr.h; path = include/clang/AST/Attr.h; sourceTree = "<group>"; };
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8DD76F6C0486A84900D96B5E /* clang */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = clang; sourceTree = BUILT_PRODUCTS_DIR; };
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DE01DA480B12ADA300AC22CE /* PPCallbacks.h */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.c.h; path = PPCallbacks.h; sourceTree = "<group>"; };
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DE06756B0C051CFE00EBBFD8 /* ParseExprCXX.cpp */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.cpp; name = ParseExprCXX.cpp; path = Parse/ParseExprCXX.cpp; sourceTree = "<group>"; };
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@ -432,6 +454,8 @@
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DED677C80B6C854100AAD4A3 /* Builtins.cpp */,
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DED62ABA0AE2EDF1001E80A4 /* Decl.cpp */,
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DE0FCB330A9C21F100248FD5 /* Expr.cpp */,
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84916BE60C161E800080778F /* Attr.h */,
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84916BE40C161E580080778F /* Attr.cpp */,
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DE3452400AEF1A2D00DBC861 /* Stmt.cpp */,
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DE75EDF00B06880E0020CF81 /* Type.cpp */,
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DE34621C0AFEB19B00DBC861 /* StmtPrinter.cpp */,
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@ -547,6 +571,12 @@
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08FB7793FE84155DC02AAC07 /* Project object */ = {
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isa = PBXProject;
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buildConfigurationList = 1DEB923508733DC60010E9CD /* Build configuration list for PBXProject "clang" */;
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buildSettings = {
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};
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buildStyles = (
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84916C3B0C1736920080778F /* Development */,
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84916C3C0C1736920080778F /* Deployment */,
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);
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hasScannedForEncodings = 1;
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mainGroup = 08FB7794FE84155DC02AAC07 /* clang */;
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projectDirPath = "";
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@ -611,6 +641,7 @@
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DE4772FA0C10EAE5002239E8 /* CGStmt.cpp in Sources */,
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DE4772FC0C10EAEC002239E8 /* CGExpr.cpp in Sources */,
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DE4264FC0C113592005A861D /* CGDecl.cpp in Sources */,
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84916BE50C161E580080778F /* Attr.cpp in Sources */,
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);
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runOnlyForDeploymentPostprocessing = 0;
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};
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