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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - "in call to f(x)" note should pretty-print original value of argument 'x', not mutated value"
href="https://bugs.llvm.org/show_bug.cgi?id=41100">41100</a>
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<th>Summary</th>
<td>"in call to f(x)" note should pretty-print original value of argument 'x', not mutated value
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>arthur.j.odwyer@gmail.com
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
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<pre>When Clang prints diagnostic notes of the form "...in call to f(arg1,
arg2)...", it seems to lose track of the arguments' ORIGINAL values. Clang ends
up pretty-printing the CHANGED values of those arguments. This can be very
confusing, especially when there's recursion involved, because the text of the
diagnostic will appear to be talking about a call that never appears in the
source code (or worse, a call that coincidentally DOES appear in the source
code, but isn't the culprit). Here's a reduced test case:
```
// <a href="https://godbolt.org/z/PIL0lW">https://godbolt.org/z/PIL0lW</a>
constexpr int f(int i) {
i = -i;
return 1 << i;
}
static_assert(f(1));
```
The problematic part of the following error message is where it mentions "call
to 'f(-1)'". It should mention "call to 'f(1)'" instead.
```
<source>:7:15: error: static_assert expression is not an integral constant
expression
static_assert(f(1));
^~~~
<source>:4:14: note: negative shift count -1
return 1 << i;
^
<source>:7:15: note: in call to 'f(-1)'
static_assert(f(1));
^
1 error generated.
```</pre>
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