Fix Makefile handling of user CXXFLAGS & also add a DEBUG flag - #990
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The way `CXXFLAGS` and other flags were being set meant that users had to add the default values (`-std=c++17 -fopenmp -O3` etc) if they set the flags at all. The new approach here adds the user values to the existing ones, so that they can override values more selectively. This also adds a DEBUG flag that switches between using `-g -O0` and the regular `-O3` option.
mhucka
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January 6, 2026 04:11
mhucka
enabled auto-merge
January 6, 2026 04:11
Clang doesn't understand `-flto=auto` and G++ doesn't understand `-flto`.
sergeisakov
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Jan 6, 2026
mhucka
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Jan 18, 2026
…umlib#990) The way `CXXFLAGS` and other flags were being set meant that users had to add the default values (`-std=c++17 -fopenmp -O3` etc) if they set the flags at all, or else lose the defaults. This was error-prone and suboptimal. The change here makes it so that the user values are appended at the end of the defaults, so that they can override values. This PR also adds a DEBUG flag that switches between using `-g -O0` and the regular `-O3` option. Developers can invoke it using, e.g., `make DEBUG=1`.
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The way
CXXFLAGSand other flags were being set meant that users had to add the default values (-std=c++17 -fopenmp -O3etc) if they set the flags at all, or else lose the defaults. This was error-prone and suboptimal. The change here makes it so that the user values are appended at the end of the defaults, so that they can override values.This PR also adds a DEBUG flag that switches between using
-g -O0and the regular-O3option. Developers can invoke it using, e.g.,make DEBUG=1.