diff options
Diffstat (limited to 'www/compatibility.html')
| -rw-r--r-- | www/compatibility.html | 95 |
1 files changed, 47 insertions, 48 deletions
diff --git a/www/compatibility.html b/www/compatibility.html index 725c52ff4b..de864eda4f 100644 --- a/www/compatibility.html +++ b/www/compatibility.html @@ -188,10 +188,9 @@ use the API calls instead of calls like <tt>__builtin_ia32_paddw128</tt>.</p> different type. Clang produces an error on similar code, e.g.,</p> <pre> -lvalue.c:2:3: error: assignment to cast is illegal, lvalue casts are not - supported +<b>lvalue.c:2:3: <span class="error">error:</span> assignment to cast is illegal, lvalue casts are not supported</b> (int*)addr = val; - ^~~~~~~~~~ ~ +<span class="caret"> ^~~~~~~~~~ ~</span> </pre> <p>To fix this problem, move the cast to the right-hand side. In this @@ -232,12 +231,12 @@ the stack is fresh, i.e. still zeroed.) Therefore, Clang rejects this code with a hard error:</p> <pre> -t.c:3:5: error: goto into protected scope +<b>t.c:3:5: <span class="error">error:</span> goto into protected scope</b> goto error; - ^ -t.c:5:15: note: jump bypasses setup of __block variable +<span class="caret"> ^</span> +<b>t.c:5:15: <span class="note">note:</note></b> jump bypasses setup of __block variable __block int result; - ^ +<span class="caret"> ^</span> </pre> <p>The fix is to rewrite the code to not require jumping into a @@ -308,10 +307,9 @@ rejects the instruction with this error message: </p> <pre> -<inline asm>:3:1: error: ambiguous instructions require an explicit suffix (could be 'addb', 'addw', 'addl', or 'addq') +<b><inline asm>:3:1: <span class="error">error:</span> ambiguous instructions require an explicit suffix (could be 'addb', 'addw', 'addl', or 'addq')</b> add $4, (%rax) -^ -1 error generated. +<span class="caret">^</span> </pre> <p>To fix this compatibility issue, add an explicit suffix to the instruction: @@ -331,9 +329,9 @@ can, among other things, be cast to a different type. Clang treats type-cast of <code>super</code>:</p> <pre> -super.m:11:12: error: cannot cast 'super' (it isn't an expression) +<b>super.m:11:12: <span class="error">error:</span> cannot cast 'super' (it isn't an expression)</b> [(Super*)super add:4]; - ~~~~~~~~^ +<span class="caret"> ~~~~~~~~^</span> </pre> <p>To fix this problem, remove the type cast, e.g.</p> @@ -352,10 +350,9 @@ Objective-C class may change over time as instance variables are added ABI:</p> <pre> -sizeof.m:4:14: error: invalid application of 'sizeof' to interface 'NSArray' in - non-fragile ABI +<b>sizeof.m:4:14: <span class="error">error:</span> invalid application of 'sizeof' to interface 'NSArray' in non-fragile ABI</b> int size = sizeof(NSArray); - ^ ~~~~~~~~~ +<span class="caret"> ^ ~~~~~~~~~</span> </pre> <p>Code that relies on the size of an Objective-C class is likely to @@ -377,12 +374,12 @@ this problem, use the Objective-C runtime API function internal Objective-C structures as implementation detail and won't do implicit conversions: <pre> -t.mm:11:2: error: no matching function for call to 'f' +<b>t.mm:11:2: <span class="error">error:</span> no matching function for call to 'f'</b> f((struct objc_object *)p); - ^ -t.mm:5:6: note: candidate function not viable: no known conversion from 'struct objc_object *' to 'id' for 1st argument +<span class="caret"> ^</span> +<b>t.mm:5:6: <span class="note">note:</note></b> candidate function not viable: no known conversion from 'struct objc_object *' to 'id' for 1st argument void f(id x); - ^ +<span class="caret"> ^</span> </pre> <p>Code should use types <tt>id</tt>, <tt>SEL</tt>, and <tt>Class</tt> @@ -465,15 +462,16 @@ int main() { <p>Clang complains: -<pre> <b>my_file.cpp:2:10: <span class="error">error:</span> call to function 'Multiply' that is neither visible in the template definition nor found by argument-dependent lookup</b> - return Multiply(x, x); - <span class="caret"> ^</span> - <b>my_file.cpp:10:3: <span class="note">note:</span> in instantiation of function template specialization 'Squared<int>' requested here</b> - Squared(5); - <span class="caret"> ^</span> - <b>my_file.cpp:5:5: <span class="note">note:</span> 'Multiply' should be declared prior to the call site</b> - int Multiply(int x, int y) { - <span class="caret"> ^</span> +<pre> +<b>my_file.cpp:2:10: <span class="error">error:</span> call to function 'Multiply' that is neither visible in the template definition nor found by argument-dependent lookup</b> + return Multiply(x, x); +<span class="caret"> ^</span> +<b>my_file.cpp:10:3: <span class="note">note:</span></b> in instantiation of function template specialization 'Squared<int>' requested here + Squared(5); +<span class="caret"> ^</span> +<b>my_file.cpp:5:5: <span class="note">note:</span></b> 'Multiply' should be declared prior to the call site +int Multiply(int x, int y) { +<span class="caret"> ^</span> </pre> <p>The C++ standard says that unqualified names like <q>Multiply</q> @@ -526,15 +524,16 @@ void Use() { <p>Again, Clang complains:</p> -<pre> <b>my_file2.cpp:5:13: <span class="error">error:</span> call to function 'operator<<' that is neither visible in the template definition nor found by argument-dependent lookup</b> - std::cout << value << "\n"; - <span class="caret"> ^</span> - <b>my_file2.cpp:17:3: <span class="error">note:</span> in instantiation of function template specialization 'Dump<ns::Data>' requested here</b> - Dump(ns::Data()); - <span class="caret"> ^</span> - <b>my_file2.cpp:12:15: <span class="error">note:</span> 'operator<<' should be declared prior to the call site or in namespace 'ns'</b> - std::ostream& operator<<(std::ostream& out, ns::Data data) { - <span class="caret"> ^</span> +<pre> +<b>my_file2.cpp:5:13: <span class="error">error:</span> call to function 'operator<<' that is neither visible in the template definition nor found by argument-dependent lookup</b> + std::cout << value << "\n"; +<span class="caret"> ^</span> +<b>my_file2.cpp:17:3: <span class="note">note:</span></b> in instantiation of function template specialization 'Dump<ns::Data>' requested here + Dump(ns::Data()); +<span class="caret"> ^</span> +<b>my_file2.cpp:12:15: <span class="note">note:</span></b> 'operator<<' should be declared prior to the call site or in namespace 'ns' +std::ostream& operator<<(std::ostream& out, ns::Data data) { +<span class="caret"> ^</span> </pre> <p>Just like before, unqualified lookup didn't find any declarations @@ -587,18 +586,18 @@ Clang correctly rejects it with the following errors (when <tt>Derived</tt> is eventually instantiated): <pre> -my_file.cpp:8:5: error: use of undeclared identifier 'DoThis' +<b>my_file.cpp:8:5: <span class="error">error:</span> use of undeclared identifier 'DoThis'</b> DoThis(x); - ^ +<span class="caret"> ^</span> this-> -my_file.cpp:2:8: note: must qualify identifier to find this declaration in dependent base class +<b>my_file.cpp:2:8: <span class="note">note:</note></b> must qualify identifier to find this declaration in dependent base class void DoThis(T x) {} - ^ -my_file.cpp:9:5: error: use of undeclared identifier 'DoThat' +<span class="caret"> ^</span> +<b>my_file.cpp:9:5: <span class="error">error:</span> use of undeclared identifier 'DoThat'</b> DoThat(x); - ^ +<span class="caret"> ^</span> this-> -my_file.cpp:3:15: note: must qualify identifier to find this declaration in dependent base class +<b>my_file.cpp:3:15: <span class="note">note:</note></b> must qualify identifier to find this declaration in dependent base class static void DoThat(T x) {} </pre> @@ -820,13 +819,13 @@ void g(Base *p) { <p>Clang produces the following error:</p> <pre> -downcast.mm:6:3: error: no matching function for call to 'f' +<b>downcast.mm:6:3: <span class="error">error:</span> no matching function for call to 'f'</b> f(p); - ^ -downcast.mm:4:6: note: candidate function not viable: cannot convert from +<span class="caret"> ^</span> +<b>downcast.mm:4:6: <span class="note">note:</note></b> candidate function not viable: cannot convert from superclass 'Base *' to subclass 'Derived *' for 1st argument void f(Derived *p); - ^ +<span class="caret"> ^</span> </pre> <p>If the downcast is actually correct (e.g., because the code has |