[PATCH] libcamera: matrix: Fix compilation error in inverse() function

[Laurent Pinchart]

Some gcc versions report uninitialized variable usage:

In member function ‘constexpr T& libcamera::Span<T, 4294967295>::operator[](size_type) const [with T = unsigned int]’,
    inlined from ‘void libcamera::matrixInvert(Span<const T>, Span<T, 4294967295>, unsigned int, Span<T, 4294967295>, Span<unsigned int>)::MatrixAccessor::swap(unsigned int, unsigned int) [with T = float]’ at ../../src/libcamera/matrix.cpp:194:13,
    inlined from ‘bool libcamera::matrixInvert(Span<const T>, Span<T, 4294967295>, unsigned int, Span<T, 4294967295>, Span<unsigned int>) [with T = float]’ at ../../src/libcamera/matrix.cpp:255:14:
../../include/libcamera/base/span.h:362:76: error: ‘row’ may be used uninitialized [-Werror=maybe-uninitialized]
  362 |         constexpr reference operator[](size_type idx) const { return data()[idx]; }
      |                                                                      ~~~~~~^
../../src/libcamera/matrix.cpp: In function ‘bool libcamera::matrixInvert(Span<const T>, Span<T, 4294967295>, unsigned int, Span<T, 4294967295>, Span<unsigned int>) [with T = float]’:
../../src/libcamera/matrix.cpp:232:30: note: ‘row’ was declared here
  232 |                 unsigned int row;
      |                              ^~~

This is a false positive. Fix it by initializing the variable when
declaring it.

Fixes: 6287ceff5aba ("libcamera: matrix: Add inverse() function")
Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/matrix.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcamera/matrix.cpp b/src/libcamera/matrix.cpp
index ed22263b58f8..b7c07e896538 100644
--- a/src/libcamera/matrix.cpp
+++ b/src/libcamera/matrix.cpp
@@ -229,7 +229,7 @@ bool matrixInvert(Span<const T> dataIn, Span<T> dataOut, unsigned int dim,
 		 * Locate the next pivot. To improve numerical stability, use
 		 * the row with the largest value in the pivot's column.
 		 */
-		unsigned int row;
+		unsigned int row = pivot;
 		T maxValue{ 0 };
 
 		for (unsigned int i = pivot; i < dim; ++i) {

base-commit: efdbe3969841e342c30dfdced38b6ad9ad55dccf
-- 
Regards,

Laurent Pinchart