msvc-cl

Name: msvc-cl
Author: mohitmishra786

333installs19forks

How to install msvc-cl?

mohitmishra786/low-level-dev-skills/msvc-cl

$npx -y skills add mohitmishra786/low-level-dev-skills --skill msvc-cl

Installs into the current project.

Summary

MSVC cl.exe and clang-cl skill for Windows C/C++ projects. Use when configuring Visual Studio builds, MSBuild, or clang-cl as a drop-in MSVC replacement. Covers translating GCC/Clang flags to MSVC equivalents, runtime library selection, Windows SDK setup, and diagnosing MSVC-spec

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SKILL.md

1	# MSVC cl.exe and clang-cl
2
3	## Purpose
4
5	Guide agents through Windows C/C++ compilation: MSVC `cl.exe`, `clang-cl` as MSVC-compatible driver, MSBuild project settings, and runtime library choices.
6
7	## Triggers
8
9	- "How do I compile with MSVC from the command line?"
10	- "What is the MSVC equivalent of `-O2`?"
11	- "/MT vs /MD — which do I use?"
12	- "How do I use clang-cl instead of cl.exe?"
13	- "I'm getting LNK errors on Windows"
14	- "How do I generate PDB files?"
15
16	## Workflow
17
18	### 1. Set up the environment
19
20	MSVC requires the Visual Studio environment variables. Use the Developer Command Prompt or set up manually:
21
22	```cmd
23	REM x64 native
24	"C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
25
26	REM x86 cross (host x64, target x86)
27	"...\vcvarsamd64_x86.bat"
28
29	REM Check compiler version
30	cl /?
31	```
32
33	In CMake, use the "Visual Studio 17 2022" generator or pass `-DCMAKE_GENERATOR="Visual Studio 17 2022"`.
34
35	### 2. Flag translation: GCC → MSVC
36
37	\| GCC/Clang \| MSVC cl.exe \| Notes \|
38	\|-----------\|-------------\|-------\|
39	\| `-O0` \| `/Od` \| Debug, no optimisation \|
40	\| `-O1` \| `/O1` \| Minimise size \|
41	\| `-O2` \| `/O2` \| Maximise speed \|
42	\| `-O3` \| `/Ox` \| Full optimisation \|
43	\| `-Os` \| `/Os` \| Favour size \|
44	\| `-g` \| `/Zi` \| PDB debug info \|
45	\| `-g` (embedded) \| `/Z7` \| Debug info in object file \|
46	\| `-Wall` \| `/W3` or `/W4` \| Warning level \|
47	\| `-Werror` \| `/WX` \| Warnings as errors \|
48	\| `-std=c++17` \| `/std:c++17` \| Standard selection \|
49	\| `-DFOO=1` \| `/DFOO=1` \| Preprocessor define \|
50	\| `-I path` \| `/I path` \| Include path \|
51	\| `-c` \| `/c` \| Compile only (no link) \|
52	\| `-o out` \| `/Fe:out.exe` or `/Fo:out.obj` \| Output file \|
53	\| `-shared` \| `/LD` \| Build DLL \|
54	\| `-fPIC` \| (implicit on Windows) \| Not needed on Windows \|
55	\| `-flto` \| `/GL` (compile) + `/LTCG` (link) \| Whole program optimisation \|
56
57	### 3. Runtime library selection
58
59	This is the most common source of LNK errors on Windows.
60
61	\| Flag \| Runtime \| Use case \|
62	\|------\|---------\|---------\|
63	\| `/MD` \| `MSVCRT.dll` (dynamic) \| Release, DLL linkage (recommended default) \|
64	\| `/MDd` \| `MSVCRTd.dll` (debug dynamic) \| Debug builds \|
65	\| `/MT` \| Static CRT \| Standalone exe; avoid mixing with DLLs \|
66	\| `/MTd` \| Static CRT debug \| Debug + static \|
67
68	Rule: All objects and libraries in a link must use the same runtime. Mixing `/MT` and `/MD` causes `LNK2038: mismatch detected`.
69
70	### 4. clang-cl
71
72	`clang-cl` is Clang's MSVC-compatible driver. It accepts `cl.exe`-style flags and can replace `cl.exe` in most MSBuild/CMake projects.
73
74	```cmd
75	REM Install: part of LLVM Windows release or VS "LLVM" component
76
77	REM Basic usage (MSVC-style flags)
78	clang-cl /O2 /std:c++17 /MD src.cpp /Fe:prog.exe
79
80	REM Pass Clang-native flags with /clang:
81	clang-cl /O2 /clang:-Rpass=inline src.cpp /Fe:prog.exe
82
83	REM Use in CMake
84	cmake -DCMAKE_C_COMPILER=clang-cl -DCMAKE_CXX_COMPILER=clang-cl ..
85	```
86
87	Minimum Clang version for MSVC STL compatibility: Clang 8+. For C++20 features with MSVC STL: Clang 14+.
88
89	Source: <https://learn.microsoft.com/en-us/cpp/build/clang-support-msbuild>
90
91	### 5. PDB files and debugging
92
93	```cmd
94	REM Compile with /Zi (external PDB) and /Fd (PDB name)
95	cl /Zi /Fd:prog.pdb /O2 src.cpp /link /DEBUG
96
97	REM /Z7: debug info embedded in .obj (no separate PDB for objects)
98	cl /Z7 /O2 src.cpp /link /DEBUG /PDB:prog.pdb
99	```
100
101	For WinDbg or VS debugger, ensure the PDB is alongside the executable or set the symbol path.
102
103	### 6. Common LNK errors
104
105	\| Error \| Cause \| Fix \|
106	\|-------\|-------\|-----\|
107	\| `LNK2019: unresolved external` \| Missing `.lib` \| Add library in project settings or `/link foo.lib` \|
108	\| `LNK2038: mismatch detected for 'RuntimeLibrary'` \| Mixed `/MT` and `/MD` \| Unify all to `/MD` or `/MT` \|
109	\| `LNK1104: cannot open file 'foo.lib'` \| Library not in search path \| Add path via `/LIBPATH:` or `LIB` env var \|
110	\| `LNK2005: already defined` \| Multiple definitions \| Use `__declspec(selectany)` or check for duplicate definitions \|
111	\| `LNK4098: defaultlib 'LIBCMT' conflicts` \| Runtime mismatch \| Explicitly pass `/NODEFAULTLIB:LIBCMT` or unify runtimes \|
112
113	### 7. Useful cl.exe flags
114
115	```cmd
116	REM Preprocessed output
117	cl /P src.cpp # produces src.i
118
119	REM Assembly output
120	cl /FA /O2 src.cpp # produces src.asm (MASM syntax)
121	cl /FAs # interleave source + asm
122
123	REM Show include files
124	cl /showIncludes src.cpp
125
126	REM Compiler version
127	cl /? 2>&1 \| findstr /i "version"
128	```
129
130	For flag details, see [references/flags.md](references/flags.md).
131
132	## Related skills
133
134	- Use `skills/compilers/clang` for clang-cl's Clang-native diagnostics
135	- Use `skills/build-systems/cmake` for CMake

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6 picks

Type

msvc-cl

333installs19forks

View on GitHub

How to install msvc-cl?

mohitmishra786/low-level-dev-skills/msvc-cl

$npx -y skills add mohitmishra786/low-level-dev-skills --skill msvc-cl

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# MSVC cl.exe and clang-cl
2
3	## Purpose
4
5	Guide agents through Windows C/C++ compilation: MSVC `cl.exe`, `clang-cl` as MSVC-compatible driver, MSBuild project settings, and runtime library choices.
6
7	## Triggers
8
9	- "How do I compile with MSVC from the command line?"
10	- "What is the MSVC equivalent of `-O2`?"
11	- "/MT vs /MD — which do I use?"
12	- "How do I use clang-cl instead of cl.exe?"
13	- "I'm getting LNK errors on Windows"
14	- "How do I generate PDB files?"
15
16	## Workflow
17
18	### 1. Set up the environment
19
20	MSVC requires the Visual Studio environment variables. Use the Developer Command Prompt or set up manually:
21
22	```cmd
23	REM x64 native
24	"C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
25
26	REM x86 cross (host x64, target x86)
27	"...\vcvarsamd64_x86.bat"
28
29	REM Check compiler version
30	cl /?
31	```
32
33	In CMake, use the "Visual Studio 17 2022" generator or pass `-DCMAKE_GENERATOR="Visual Studio 17 2022"`.
34
35	### 2. Flag translation: GCC → MSVC
36
37	\| GCC/Clang \| MSVC cl.exe \| Notes \|
38	\|-----------\|-------------\|-------\|
39	\| `-O0` \| `/Od` \| Debug, no optimisation \|
40	\| `-O1` \| `/O1` \| Minimise size \|
41	\| `-O2` \| `/O2` \| Maximise speed \|
42	\| `-O3` \| `/Ox` \| Full optimisation \|
43	\| `-Os` \| `/Os` \| Favour size \|
44	\| `-g` \| `/Zi` \| PDB debug info \|
45	\| `-g` (embedded) \| `/Z7` \| Debug info in object file \|
46	\| `-Wall` \| `/W3` or `/W4` \| Warning level \|
47	\| `-Werror` \| `/WX` \| Warnings as errors \|
48	\| `-std=c++17` \| `/std:c++17` \| Standard selection \|
49	\| `-DFOO=1` \| `/DFOO=1` \| Preprocessor define \|
50	\| `-I path` \| `/I path` \| Include path \|
51	\| `-c` \| `/c` \| Compile only (no link) \|
52	\| `-o out` \| `/Fe:out.exe` or `/Fo:out.obj` \| Output file \|
53	\| `-shared` \| `/LD` \| Build DLL \|
54	\| `-fPIC` \| (implicit on Windows) \| Not needed on Windows \|
55	\| `-flto` \| `/GL` (compile) + `/LTCG` (link) \| Whole program optimisation \|
56
57	### 3. Runtime library selection
58
59	This is the most common source of LNK errors on Windows.
60
61	\| Flag \| Runtime \| Use case \|
62	\|------\|---------\|---------\|
63	\| `/MD` \| `MSVCRT.dll` (dynamic) \| Release, DLL linkage (recommended default) \|
64	\| `/MDd` \| `MSVCRTd.dll` (debug dynamic) \| Debug builds \|
65	\| `/MT` \| Static CRT \| Standalone exe; avoid mixing with DLLs \|
66	\| `/MTd` \| Static CRT debug \| Debug + static \|
67
68	Rule: All objects and libraries in a link must use the same runtime. Mixing `/MT` and `/MD` causes `LNK2038: mismatch detected`.
69
70	### 4. clang-cl
71
72	`clang-cl` is Clang's MSVC-compatible driver. It accepts `cl.exe`-style flags and can replace `cl.exe` in most MSBuild/CMake projects.
73
74	```cmd
75	REM Install: part of LLVM Windows release or VS "LLVM" component
76
77	REM Basic usage (MSVC-style flags)
78	clang-cl /O2 /std:c++17 /MD src.cpp /Fe:prog.exe
79
80	REM Pass Clang-native flags with /clang:
81	clang-cl /O2 /clang:-Rpass=inline src.cpp /Fe:prog.exe
82
83	REM Use in CMake
84	cmake -DCMAKE_C_COMPILER=clang-cl -DCMAKE_CXX_COMPILER=clang-cl ..
85	```
86
87	Minimum Clang version for MSVC STL compatibility: Clang 8+. For C++20 features with MSVC STL: Clang 14+.
88
89	Source: <https://learn.microsoft.com/en-us/cpp/build/clang-support-msbuild>
90
91	### 5. PDB files and debugging
92
93	```cmd
94	REM Compile with /Zi (external PDB) and /Fd (PDB name)
95	cl /Zi /Fd:prog.pdb /O2 src.cpp /link /DEBUG
96
97	REM /Z7: debug info embedded in .obj (no separate PDB for objects)
98	cl /Z7 /O2 src.cpp /link /DEBUG /PDB:prog.pdb
99	```
100
101	For WinDbg or VS debugger, ensure the PDB is alongside the executable or set the symbol path.
102
103	### 6. Common LNK errors
104
105	\| Error \| Cause \| Fix \|
106	\|-------\|-------\|-----\|
107	\| `LNK2019: unresolved external` \| Missing `.lib` \| Add library in project settings or `/link foo.lib` \|
108	\| `LNK2038: mismatch detected for 'RuntimeLibrary'` \| Mixed `/MT` and `/MD` \| Unify all to `/MD` or `/MT` \|
109	\| `LNK1104: cannot open file 'foo.lib'` \| Library not in search path \| Add path via `/LIBPATH:` or `LIB` env var \|
110	\| `LNK2005: already defined` \| Multiple definitions \| Use `__declspec(selectany)` or check for duplicate definitions \|
111	\| `LNK4098: defaultlib 'LIBCMT' conflicts` \| Runtime mismatch \| Explicitly pass `/NODEFAULTLIB:LIBCMT` or unify runtimes \|
112
113	### 7. Useful cl.exe flags
114
115	```cmd
116	REM Preprocessed output
117	cl /P src.cpp # produces src.i
118
119	REM Assembly output
120	cl /FA /O2 src.cpp # produces src.asm (MASM syntax)
121	cl /FAs # interleave source + asm
122
123	REM Show include files
124	cl /showIncludes src.cpp
125
126	REM Compiler version
127	cl /? 2>&1 \| findstr /i "version"
128	```
129
130	For flag details, see [references/flags.md](references/flags.md).
131
132	## Related skills
133
134	- Use `skills/compilers/clang` for clang-cl's Clang-native diagnostics
135	- Use `skills/build-systems/cmake` for CMake

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Type