[cfe-commits] r68207 - in /cfe/trunk: include/clang/AST/Type.h lib/AST/Type.cpp lib/Sema/Sema.cpp test/SemaCXX/qualified-names-diag.cpp test/SemaTemplate/qualified-names-diag.cpp www/diagnostics.html
Douglas Gregor
dgregor at apple.com
Wed Apr 1 08:47:24 PDT 2009
Author: dgregor
Date: Wed Apr 1 10:47:24 2009
New Revision: 68207
URL: http://llvm.org/viewvc/llvm-project?rev=68207&view=rev
Log:
Give Type::getDesugaredType a "for-display" mode that can apply more
heuristics to determine when it's useful to desugar a type for display
to the user. Introduce two C++-specific heuristics:
- For a qualified type (like "foo::bar"), only produce a new
desugred type if desugaring the qualified type ("bar", in this
case) produces something interesting. For example, if "foo::bar"
refers to a class named "bar", don't desugar. However, if
"foo::bar" refers to a typedef of something else, desugar to that
something else. This gives some useful desugaring such as
"foo::bar (aka 'int')".
- Don't desugar class template specialization types like
"basic_string<char>" down to their underlying "class
basic_string<char, char_traits<char>, allocator<char>>, etc.";
it's better just to leave such types alone.
Update diagnostics.html with some discussion and examples of type
preservation in C++, showing qualified names and class template
specialization types.
Modified:
cfe/trunk/include/clang/AST/Type.h
cfe/trunk/lib/AST/Type.cpp
cfe/trunk/lib/Sema/Sema.cpp
cfe/trunk/test/SemaCXX/qualified-names-diag.cpp
cfe/trunk/test/SemaTemplate/qualified-names-diag.cpp
cfe/trunk/www/diagnostics.html
Modified: cfe/trunk/include/clang/AST/Type.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Type.h?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Type.h (original)
+++ cfe/trunk/include/clang/AST/Type.h Wed Apr 1 10:47:24 2009
@@ -162,7 +162,7 @@
/// to getting the canonical type, but it doesn't remove *all* typedefs. For
/// example, it returns "T*" as "T*", (not as "int*"), because the pointer is
/// concrete.
- QualType getDesugaredType() const;
+ QualType getDesugaredType(bool ForDisplay = false) const;
/// operator==/!= - Indicate whether the specified types and qualifiers are
/// identical.
@@ -461,7 +461,7 @@
/// to getting the canonical type, but it doesn't remove *all* typedefs. For
/// example, it returns "T*" as "T*", (not as "int*"), because the pointer is
/// concrete.
- QualType getDesugaredType() const;
+ QualType getDesugaredType(bool ForDisplay = false) const;
/// More type predicates useful for type checking/promotion
bool isPromotableIntegerType() const; // C99 6.3.1.1p2
Modified: cfe/trunk/lib/AST/Type.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Type.cpp?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Type.cpp (original)
+++ cfe/trunk/lib/AST/Type.cpp Wed Apr 1 10:47:24 2009
@@ -75,8 +75,13 @@
/// to getting the canonical type, but it doesn't remove *all* typedefs. For
/// example, it returns "T*" as "T*", (not as "int*"), because the pointer is
/// concrete.
-QualType QualType::getDesugaredType() const {
- return getTypePtr()->getDesugaredType()
+///
+/// \param ForDisplay When true, the desugaring is provided for
+/// display purposes only. In this case, we apply more heuristics to
+/// decide whether it is worth providing a desugared form of the type
+/// or not.
+QualType QualType::getDesugaredType(bool ForDisplay) const {
+ return getTypePtr()->getDesugaredType(ForDisplay)
.getWithAdditionalQualifiers(getCVRQualifiers());
}
@@ -86,7 +91,12 @@
/// to getting the canonical type, but it doesn't remove *all* typedefs. For
/// example, it return "T*" as "T*", (not as "int*"), because the pointer is
/// concrete.
-QualType Type::getDesugaredType() const {
+///
+/// \param ForDisplay When true, the desugaring is provided for
+/// display purposes only. In this case, we apply more heuristics to
+/// decide whether it is worth providing a desugared form of the type
+/// or not.
+QualType Type::getDesugaredType(bool ForDisplay) const {
if (const TypedefType *TDT = dyn_cast<TypedefType>(this))
return TDT->LookThroughTypedefs().getDesugaredType();
if (const TypeOfExprType *TOE = dyn_cast<TypeOfExprType>(this))
@@ -95,16 +105,26 @@
return TOT->getUnderlyingType().getDesugaredType();
if (const TemplateSpecializationType *Spec
= dyn_cast<TemplateSpecializationType>(this)) {
+ if (ForDisplay)
+ return QualType(this, 0);
+
QualType Canon = Spec->getCanonicalTypeInternal();
if (Canon->getAsTemplateSpecializationType())
return QualType(this, 0);
return Canon->getDesugaredType();
}
- if (const QualifiedNameType *QualName = dyn_cast<QualifiedNameType>(this))
- return QualName->getNamedType().getDesugaredType();
+ if (const QualifiedNameType *QualName = dyn_cast<QualifiedNameType>(this)) {
+ if (ForDisplay) {
+ // If desugaring the type that the qualified name is referring to
+ // produces something interesting, that's our desugared type.
+ QualType NamedType = QualName->getNamedType().getDesugaredType();
+ if (NamedType != QualName->getNamedType())
+ return NamedType;
+ } else
+ return QualName->getNamedType().getDesugaredType();
+ }
- // FIXME: remove this cast.
- return QualType(const_cast<Type*>(this), 0);
+ return QualType(this, 0);
}
/// isVoidType - Helper method to determine if this is the 'void' type.
Modified: cfe/trunk/lib/Sema/Sema.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/Sema.cpp (original)
+++ cfe/trunk/lib/Sema/Sema.cpp Wed Apr 1 10:47:24 2009
@@ -40,7 +40,7 @@
// If this is a sugared type (like a typedef, typeof, etc), then unwrap one
// level of the sugar so that the type is more obvious to the user.
- QualType DesugaredTy = Ty->getDesugaredType();
+ QualType DesugaredTy = Ty->getDesugaredType(true);
DesugaredTy.setCVRQualifiers(DesugaredTy.getCVRQualifiers() |
Ty.getCVRQualifiers());
Modified: cfe/trunk/test/SemaCXX/qualified-names-diag.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/qualified-names-diag.cpp?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/qualified-names-diag.cpp (original)
+++ cfe/trunk/test/SemaCXX/qualified-names-diag.cpp Wed Apr 1 10:47:24 2009
@@ -21,12 +21,12 @@
void test() {
foo::wibble::x a;
::bar::y b;
- a + b; // expected-error{{invalid operands to binary expression ('foo::wibble::x' (aka 'struct foo::wibble::x') and '::bar::y' (aka 'int'))}}
+ a + b; // expected-error{{invalid operands to binary expression ('foo::wibble::x' and '::bar::y' (aka 'int'))}}
::foo::wibble::bar::wonka::x::y c;
- c + b; // expected-error{{invalid operands to binary expression ('::foo::wibble::bar::wonka::x::y' (aka 'struct foo::wibble::bar::wonka::x::y') and '::bar::y' (aka 'int'))}}
+ c + b; // expected-error{{invalid operands to binary expression ('::foo::wibble::bar::wonka::x::y' and '::bar::y' (aka 'int'))}}
- (void)sizeof(bar::incomplete); // expected-error{{invalid application of 'sizeof' to an incomplete type 'bar::incomplete' (aka 'struct bar::incomplete')}}
+ (void)sizeof(bar::incomplete); // expected-error{{invalid application of 'sizeof' to an incomplete type 'bar::incomplete'}}
}
int ::foo::wibble::bar::wonka::x::y::* ptrmem;
Modified: cfe/trunk/test/SemaTemplate/qualified-names-diag.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/qualified-names-diag.cpp?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/qualified-names-diag.cpp (original)
+++ cfe/trunk/test/SemaTemplate/qualified-names-diag.cpp Wed Apr 1 10:47:24 2009
@@ -12,5 +12,5 @@
std::vector<INT> v1;
vector<Real> v2;
- v1 = v2; // expected-error{{incompatible type assigning 'vector<Real>' (aka 'class std::vector<float>'), expected 'std::vector<INT>' (aka 'class std::vector<int>')}}
+ v1 = v2; // expected-error{{incompatible type assigning 'vector<Real>', expected 'std::vector<INT>'}}
}
Modified: cfe/trunk/www/diagnostics.html
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/diagnostics.html?rev=68207&r1=68206&r2=68207&view=diff
==============================================================================
--- cfe/trunk/www/diagnostics.html (original)
+++ cfe/trunk/www/diagnostics.html Wed Apr 1 10:47:24 2009
@@ -156,6 +156,48 @@
<p>If the user was somehow confused about how the system "pid_t" typedef is
defined, Clang helpfully displays it with "aka".</p>
+<p>In C++, type preservation includes retaining any qualification written into type names. For example, if we take a small snippet of code such as:
+
+<blockquote>
+<pre>
+namespace services {
+ struct WebService { };
+}
+namespace myapp {
+ namespace servers {
+ struct Server { };
+ }
+}
+
+using namespace myapp;
+void addHTTPService(servers::Server const &server, ::services::WebService const *http) {
+ server += http;
+}
+</pre>
+</blockquote>
+
+<p>and then compile it, we see that Clang is both providing more accurate information and is retaining the types as written by the user (e.g., "servers::Server", "::services::WebService"):
+
+<pre>
+ $ <b>g++-4.2 -fsyntax-only t.cpp</b>
+ t.cpp:9: error: no match for 'operator+=' in 'server += http'
+ $ <b>clang -fsyntax-only t.cpp</b>
+ t.cpp:9:10: error: invalid operands to binary expression ('servers::Server const' and '::services::WebService const *')
+ <font color="darkgreen">server += http;</font>
+ <font color="blue">~~~~~~ ^ ~~~~</font>
+</pre>
+
+<p>Naturally, type preservation extends to uses of templates, and Clang retains information about how a particular template specialization (like <code>std::vector<Real></code>) was spelled within the source code. For example:</p>
+
+<pre>
+ $ <b>g++-4.2 -fsyntax-only t.cpp</b>
+ t.cpp:12: error: no match for 'operator=' in 'str = vec'
+ $ <b>clang -fsyntax-only t.cpp</b>
+ t.cpp:12:7: error: incompatible type assigning 'vector<Real>', expected 'std::string' (aka 'class std::basic_string<char>')
+ <font color="darkgreen">str = vec</font>;
+ <font color="blue">^ ~~~</font>
+</pre>
+
<h2>Fix-it Hints</h2>
<p>simple example + template<> example</p>
@@ -203,11 +245,6 @@
<p>In practice, we've found that this is actually more useful in multiply nested
macros that in simple ones.</p>
-<h2>C++ Fun Examples</h2>
-
-<p>...</p>
-
-
</div>
</body>
</html>
More information about the cfe-commits
mailing list