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| <a name="Test-Idioms"></a> |
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| Next: <a href="Test-Directives.html#Test-Directives" accesskey="n" rel="next">Test Directives</a>, Up: <a href="Testsuites.html#Testsuites" accesskey="u" rel="up">Testsuites</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Idioms-Used-in-Testsuite-Code"></a> |
| <h3 class="section">7.1 Idioms Used in Testsuite Code</h3> |
| |
| <p>In general, C testcases have a trailing <samp>-<var>n</var>.c</samp>, starting |
| with <samp>-1.c</samp>, in case other testcases with similar names are added |
| later. If the test is a test of some well-defined feature, it should |
| have a name referring to that feature such as |
| <samp><var>feature</var>-1.c</samp>. If it does not test a well-defined feature |
| but just happens to exercise a bug somewhere in the compiler, and a |
| bug report has been filed for this bug in the GCC bug database, |
| <samp>pr<var>bug-number</var>-1.c</samp> is the appropriate form of name. |
| Otherwise (for miscellaneous bugs not filed in the GCC bug database), |
| and previously more generally, test cases are named after the date on |
| which they were added. This allows people to tell at a glance whether |
| a test failure is because of a recently found bug that has not yet |
| been fixed, or whether it may be a regression, but does not give any |
| other information about the bug or where discussion of it may be |
| found. Some other language testsuites follow similar conventions. |
| </p> |
| <p>In the <samp>gcc.dg</samp> testsuite, it is often necessary to test that an |
| error is indeed a hard error and not just a warning—for example, |
| where it is a constraint violation in the C standard, which must |
| become an error with <samp>-pedantic-errors</samp>. The following idiom, |
| where the first line shown is line <var>line</var> of the file and the line |
| that generates the error, is used for this: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">/* { dg-bogus "warning" "warning in place of error" } */ |
| /* { dg-error "<var>regexp</var>" "<var>message</var>" { target *-*-* } <var>line</var> } */ |
| </pre></div> |
| |
| <p>It may be necessary to check that an expression is an integer constant |
| expression and has a certain value. To check that <code><var>E</var></code> has |
| value <code><var>V</var></code>, an idiom similar to the following is used: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">char x[((E) == (V) ? 1 : -1)]; |
| </pre></div> |
| |
| <p>In <samp>gcc.dg</samp> tests, <code>__typeof__</code> is sometimes used to make |
| assertions about the types of expressions. See, for example, |
| <samp>gcc.dg/c99-condexpr-1.c</samp>. The more subtle uses depend on the |
| exact rules for the types of conditional expressions in the C |
| standard; see, for example, <samp>gcc.dg/c99-intconst-1.c</samp>. |
| </p> |
| <p>It is useful to be able to test that optimizations are being made |
| properly. This cannot be done in all cases, but it can be done where |
| the optimization will lead to code being optimized away (for example, |
| where flow analysis or alias analysis should show that certain code |
| cannot be called) or to functions not being called because they have |
| been expanded as built-in functions. Such tests go in |
| <samp>gcc.c-torture/execute</samp>. Where code should be optimized away, a |
| call to a nonexistent function such as <code>link_failure ()</code> may be |
| inserted; a definition |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#ifndef __OPTIMIZE__ |
| void |
| link_failure (void) |
| { |
| abort (); |
| } |
| #endif |
| </pre></div> |
| |
| <p>will also be needed so that linking still succeeds when the test is |
| run without optimization. When all calls to a built-in function |
| should have been optimized and no calls to the non-built-in version of |
| the function should remain, that function may be defined as |
| <code>static</code> to call <code>abort ()</code> (although redeclaring a function |
| as static may not work on all targets). |
| </p> |
| <p>All testcases must be portable. Target-specific testcases must have |
| appropriate code to avoid causing failures on unsupported systems; |
| unfortunately, the mechanisms for this differ by directory. |
| </p> |
| <p>FIXME: discuss non-C testsuites here. |
| </p> |
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