add some more popular examples, color code warning: and error: like the command line.
llvm-svn: 83161
This commit is contained in:
Chris Lattner
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711ab5b8ec
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859f1b5b86
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@ -43,7 +43,7 @@ what is wrong in a particular piece of code, an example is:</p>
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$ <b>gcc-4.2 -fsyntax-only -Wformat format-strings.c</b>
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format-strings.c:91: warning: too few arguments for format
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$ <b>clang -fsyntax-only format-strings.c</b>
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format-strings.c:91:13: warning: '.*' specified field precision is missing a matching 'int' argument
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format-strings.c:91:13: <font color="magenta">warning:</font> '.*' specified field precision is missing a matching 'int' argument
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<font color="darkgreen"> printf("%.*d");</font>
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<font color="blue"> ^</font>
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</pre>
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@ -64,7 +64,7 @@ nonsensical example to illustrate this:</p>
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$ <b>gcc-4.2 -fsyntax-only t.c</b>
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t.c:7: error: invalid operands to binary + (have 'int' and 'struct A')
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$ <b>clang -fsyntax-only t.c</b>
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t.c:7:39: error: invalid operands to binary expression ('int' and 'struct A')
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t.c:7:39: <font color="red">error:</font> invalid operands to binary expression ('int' and 'struct A')
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<font color="darkgreen"> return y + func(y ? ((SomeA.X + 40) + SomeA) / 42 + SomeA.X : SomeA.X);</font>
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<font color="blue"> ~~~~~~~~~~~~~~ ^ ~~~~~</font>
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</pre>
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@ -89,7 +89,7 @@ one:</p>
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$ <b>gcc-4.2 -fsyntax-only t.c</b>
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t.c:5: error: invalid type argument of 'unary *'
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$ <b>clang -fsyntax-only t.c</b>
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t.c:5:11: error: indirection requires pointer operand ('int' invalid)
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t.c:5:11: <font color="red">error:</font> indirection requires pointer operand ('int' invalid)
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<font color="darkgreen"> int y = *SomeA.X;</font>
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<font color="blue"> ^~~~~~~~</font>
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</pre>
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@ -112,7 +112,7 @@ example P and Q have type "int*":</p>
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$ <b>gcc-4.2 -fsyntax-only t.c</b>
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#'exact_div_expr' not supported by pp_c_expression#'t.c:12: error: called object is not a function
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$ <b>clang -fsyntax-only t.c</b>
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t.c:12:8: error: called object type 'int' is not a function or function pointer
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t.c:12:8: <font color="red">error:</font> called object type 'int' is not a function or function pointer
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<font color="darkgreen"> (P-Q)();</font>
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<font color="blue"> ~~~~~^</font>
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</pre>
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@ -134,7 +134,7 @@ a typedef in C:</p>
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$ <b>gcc-4.2 -fsyntax-only t.c</b>
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t.c:15: error: invalid operands to binary / (have 'float __vector__' and 'const int *')
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$ <b>clang -fsyntax-only t.c</b>
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t.c:15:11: error: can't convert between vector values of different size ('__m128' and 'int const *')
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t.c:15:11: <font color="red">error:</font> can't convert between vector values of different size ('__m128' and 'int const *')
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<font color="darkgreen"> myvec[1]/P;</font>
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<font color="blue"> ~~~~~~~~^~</font>
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</pre>
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@ -148,7 +148,7 @@ is useful for the compiler to expose underlying details of a typedef:</p>
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$ <b>gcc-4.2 -fsyntax-only t.c</b>
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t.c:13: error: request for member 'x' in something not a structure or union
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$ <b>clang -fsyntax-only t.c</b>
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t.c:13:9: error: member reference base type 'pid_t' (aka 'int') is not a structure or union
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t.c:13:9: <font color="red">error:</font> member reference base type 'pid_t' (aka 'int') is not a structure or union
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<font color="darkgreen"> myvar = myvar.x;</font>
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<font color="blue"> ~~~~~ ^</font>
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</pre>
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@ -182,7 +182,7 @@ void addHTTPService(servers::Server const &server, ::services::WebService const
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$ <b>g++-4.2 -fsyntax-only t.cpp</b>
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t.cpp:9: error: no match for 'operator+=' in 'server += http'
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$ <b>clang -fsyntax-only t.cpp</b>
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t.cpp:9:10: error: invalid operands to binary expression ('servers::Server const' and '::services::WebService const *')
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t.cpp:9:10: <font color="red">error:</font> invalid operands to binary expression ('servers::Server const' and '::services::WebService const *')
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<font color="darkgreen">server += http;</font>
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<font color="blue">~~~~~~ ^ ~~~~</font>
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</pre>
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@ -193,7 +193,7 @@ void addHTTPService(servers::Server const &server, ::services::WebService const
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$ <b>g++-4.2 -fsyntax-only t.cpp</b>
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t.cpp:12: error: no match for 'operator=' in 'str = vec'
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$ <b>clang -fsyntax-only t.cpp</b>
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t.cpp:12:7: error: incompatible type assigning 'vector<Real>', expected 'std::string' (aka 'class std::basic_string<char>')
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t.cpp:12:7: <font color="red">error:</font> incompatible type assigning 'vector<Real>', expected 'std::string' (aka 'class std::basic_string<char>')
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<font color="darkgreen">str = vec</font>;
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<font color="blue">^ ~~~</font>
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</pre>
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@ -210,21 +210,25 @@ extension that has been considered obsolete since 1993:</p>
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<pre>
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$ <b>clang t.c</b>
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t.c:5:28: warning: use of GNU old-style field designator extension
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t.c:5:28: <font color="magenta">warning:</font> use of GNU old-style field designator extension
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<font color="darkgreen">struct point origin = { x: 0.0, y: 0.0 };</font>
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<font color="red">~~</font> <font color="blue">^</font>
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<font color="darkgreen">.x = </font>
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t.c:5:36: warning: use of GNU old-style field designator extension
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t.c:5:36: <font color="magenta">warning:</font> use of GNU old-style field designator extension
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<font color="darkgreen">struct point origin = { x: 0.0, y: 0.0 };</font>
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<font color="red">~~</font> <font color="blue">^</font>
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<font color="darkgreen">.y = </font>
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</pre>
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<p>The underlined code should be removed, then replaced with the code below the caret line (".x =" or ".y =", respectively). "Fix-it" hints are most useful for working around common user errors and misconceptions. For example, C++ users commonly forget the syntax for explicit specialization of class templates, as in the following error:</p>
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<p>The underlined code should be removed, then replaced with the code below the
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caret line (".x =" or ".y =", respectively). "Fix-it" hints are most useful for
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working around common user errors and misconceptions. For example, C++ users
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commonly forget the syntax for explicit specialization of class templates,
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as in the following error:</p>
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<pre>
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$ <b>clang t.cpp</b>
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t.cpp:9:3: error: template specialization requires 'template<>'
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t.cpp:9:3: <font color="red">error:</font> template specialization requires 'template<>'
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struct iterator_traits<file_iterator> {
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<font color="blue">^</font>
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<font color="darkgreen">template<> </font>
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@ -244,7 +248,7 @@ Clang helps you out:</p>
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t.c: In function 'test':
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t.c:80: error: invalid operands to binary < (have 'struct mystruct' and 'float')
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$ <b>clang -fsyntax-only t.c</b>
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t.c:80:3: error: invalid operands to binary expression ('typeof(P)' (aka 'struct mystruct') and 'typeof(F)' (aka 'float'))
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t.c:80:3: <font color="red">error:</font> invalid operands to binary expression ('typeof(P)' (aka 'struct mystruct') and 'typeof(F)' (aka 'float'))
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<font color="darkgreen"> X = MYMAX(P, F);</font>
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<font color="blue"> ^~~~~~~~~~~</font>
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t.c:76:94: note: instantiated from:
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@ -260,7 +264,7 @@ implements the "wwopen" class of APIs):</p>
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<pre>
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$ <b>clang -fsyntax-only t.c</b>
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t.c:22:2: warning: type specifier missing, defaults to 'int'
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t.c:22:2: <font color="magenta">warning:</font> type specifier missing, defaults to 'int'
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<font color="darkgreen"> ILPAD();</font>
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<font color="blue"> ^</font>
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t.c:17:17: note: instantiated from:
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@ -274,6 +278,45 @@ implements the "wwopen" class of APIs):</p>
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<p>In practice, we've found that this is actually more useful in multiply nested
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macros that in simple ones.</p>
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<h2>Quality of Implementation and Attention to Detail</h2>
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<p>Finally, we have put a lot of work polishing the little things, because
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little things add up over time and contribute to a great user experience. Two
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examples are:</p>
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<pre>
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$ <b>gcc-4.2 t.c</b>
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t.c: In function 'foo':
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t.c:5: error: expected ';' before '}' token
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$ <b>clang t.c</b>
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t.c:4:8: <font color="red">error:</font> expected ';' after expression
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<font color="darkgreen"> bar()</font>
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<font color="blue"> ^</font>
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<font color="blue"> ;</font>
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</pre>
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<p>This shows a trivial little tweak, where we tell you to put the semicolon at
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the end of the line that is missing it (line 8) instead of at the beginning of
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the following line (line 9). This is particularly important with fixit hints
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and caret diagnostics, because otherwise you don't get the important context.
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</p>
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<pre>
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$ <b>gcc-4.2 t.c</b>
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t.c:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token
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$ <b>clang t.c</b>
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t.c:3:1: <font color="red">error:</font> unknown type name 'foo_t'
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<font color="darkgreen">foo_t *P = 0;</font>
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<font color="blue">^</font>
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</pre>
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<p>This shows an example of much better error recovery. The message coming out
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of GCC is completely useless for diagnosing the problem, Clang tries much harder
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and produces a much more useful diagnosis of the problem.</p>
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<p>While each of these details is minor, we feel that they all add up to provide
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a much more polished experience.</p>
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</div>
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</body>
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</html>
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